Prometheus is the "Old Faithful" of the many active volcanoes on Jupiter's moon Io. A broad, umbrella-shaped plume of gas and dust has been spotted above Prometheus by NASA's Voyager and Galileo spacecraft every time the viewing conditions have been favorable. The volcano is surrounded by a prominent circular ring of bright sulfur dioxide apparently deposited by the plume. However, the origin of Prometheus' plume is a long-standing mystery: Where is the vent that is the source of all the gas and dust?
Some clues are offered by this false-color picture with a resolution of 170 meters (186 yards) per picture element, which was taken by Galileo on February 22, 2000. To the right is a dark, semi-circular, lava-filled caldera. South of it lies a fissure from which dark lava has flowed toward the west (left). The lava flow extends 90 kilometers (54 miles) from the source. Bright patches probably composed of sulfur dioxide can be seen in several places along the flow's margins. Two of these patches (near the top left edge of the dark lava, at the farthest reaches of the flow) display faint blue hazes, apparently produced by airborne dust entrained within plumes. Both of these spots are locations of newly erupted lava that has encroached on the surrounding plains since Galileo last imaged the region in October 1999. Galileo scientists are now studying whether heating of the volatile, sulfur dioxide-rich plains by encroaching hot lava might account for the persistent plume activity observed near Prometheus.
The Jet Propulsion Laboratory, Pasadena, Calif. manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology in Pasadena.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
This mosaic of images collected by NASA's Galileo spacecraft on Thanksgiving Day, November 25,1999 shows a fountain of lava spewing above the surface of Jupiter's moon Io. The active lava was hot enough to cause what the camera team describes as "bleeding" in Galileo's camera, caused when the camera's detector is so overloaded by the brightness of the target that electrons spill down across the detector. This shows up as a white blur in the image.
Most of the hot material is distributed along a wavy line which is interpreted to be hot lava shooting more than 1.5 kilometers (1-mile) high out of a long crack, or fissure, on the surface. There also appear to be additional hot areas below this line, suggesting that hot lava is flowing away from the fissure. Initial estimates of the lava temperature indicate that it is well above 1,000 Kelvin (1,300 Fahrenheit) and might even be hotter than 1,600 Kelvin (2,400 Fahrenheit).
These images were targeted to provide the first close-up view of a chain of huge calderas (large volcanic collapse pits). These calderas are some of the largest on Io and they dwarf other calderas across the solar system. At 290 by 100 kilometers (180 by 60 miles), this chain of calderas covers an area seven times larger than the largest caldera on the Earth. The new images show the complex nature of this giant caldera on Io, with smaller collapses occurring within the elongated caldera.
Also of great interest is the flat-topped mesa on the right. The scalloped margins are typical of a process geologists call "sapping," which occurs when erosion is caused by a fluid escaping from the base of a cliff. On Earth, such sapping features are caused by springs of groundwater. Similar features on Mars are one of the key pieces of evidence for past water on the Martian surface. However, on Io, the liquid is presumed to be pressurized sulfur dioxide. The liquid sulfur dioxide should change to a gas almost instantaneously upon reaching the near-vacuum of Io's surface, blasting away material at the base of the cliff. The sulfur dioxide gas eventually freezes out on the surface of Io in the form of a frost. As the frost is buried by later deposits, it can be heated and pressurized until it becomes a liquid. This liquid then flows out of the ground, completing Io's version of the "water cycle."
North is to the upper left of the picture and the Sun illuminates the surface from the lower left. The image, centered at 61.1 degrees latitude and 119.4 degrees longitude, covers an area approximately 300 by 75 kilometers (190-by-47 miles). The resolution is 185 meters (610 feet) per picture element. The image was taken at a range of 17,000 kilometers(11,000 miles) by Galileo's onboard camera.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
This five-frame sequence of New Horizons images captures the giant plume from Io's Tvashtar volcano. Snapped by the probe's Long Range Reconnaissance Imager (LORRI) as the spacecraft flew past Jupiter earlier this year, this first-ever "movie" of an Io plume clearly shows motion in the cloud of volcanic debris, which extends 330 kilometers (200 miles) above the moon's surface. Only the upper part of the plume is visible from this vantage point -- the plume's source is 130 kilometers (80 miles) below the edge of Io's disk, on the far side of the moon.
The appearance and motion of the plume is remarkably similar to an ornamental fountain on Earth, replicated on a gigantic scale. The knots and filaments that allow us to track the plume's motion are still mysterious, but this movie is likely to help scientists understand their origin, as well as provide unique information on the plume dynamics.
Io's hyperactive nature is emphasized by the fact that two other volcanic plumes are also visible off the edge of Io's disk: Masubi at the 7 o'clock position, and a very faint plume, possibly from the volcano Zal, at the 10 o'clock position. Jupiter illuminates the night side of Io, and the most prominent feature visible on the disk is the dark horseshoe shape of the volcano Loki, likely an enormous lava lake. Boosaule Mons, which at 18 kilometers (11 miles) is the highest mountain on Io and one of the highest mountains in the solar system, pokes above the edge of the disk on the right side.
The five images were obtained over an 8-minute span, with two minutes between frames, from 23:50 to 23:58 Universal Time on March 1, 2007. Io was 3.8 million kilometers (2.4 million miles) from New Horizons; the image is centered at Io coordinates 0 degrees north, 342 degrees west.
The pictures were part of a sequence designed to look at Jupiter's rings, but planners included Io in the sequence because the moon was passing behind Jupiter's rings at the time.
This mosaic of images acquired by NASA's Galileo spacecraft on February 22,2000, shows the highest resolution view ever obtained of the surface of Jupiter's volcanic moon Io, 5 to 6 meters (16 to 20 feet) per picture element. North is to the top of the images and the entire mosaic spans about 17 kilometers (11 miles) from east to west. The images are rotated relative to one another because of Galileo's great speed as it flies above the surface of Io. The image is centered at 32 degrees north latitude and 193 degrees west longitude
The Sun illuminates the surface from the right, but topographic shading is difficult to see because of the strong contrasts in brightness of the surface materials. A raised promontory at the bottom of the center image casts shadows into the lower right corner of the left image. Galileo scientists estimate that the promontory is up to 400 meters (one-fourth mile) high.
The surface is quite varied in appearance, ranging from smooth patches of material to the much rougher top of the promontory. In places, layers of bright and dark material appear to have been exposed by some process of erosion. Sublimation of sulfur-dioxide-rich substances, their transition from solid to gaseous form, may also play a role in the segregation of bright and dark materials. Several intriguing, narrow, channel-like features about 10 meters (11 yards) wide and a few hundred meters (yards) long can be seen. Arrows in the inset indicate some examples of these. These features may provide evidence for springs of some liquid, probably a sulfur compound rather than water.
The Jet Propulsion Laboratory, Pasadena, Calif. manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA02562: Very High Resolution View of Io's Surface sur le site de la NASA.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01064: Global View of Io (Natural and False/Enhanced Color) sur le site de la NASA.
Repeated flybys of Io by NASA's Galileo spacecraft have allowed scientists to develop an understanding of Io's Tohil-Culann region of interconnected volcanoes and mountains.
An active volcano named Culann Patera (top center) is one of the most colorful volcanoes on Jupiter's innermost large moon (see PIA02535). It lies just north of an enigmatic mountain called Tohil Mons (see PIA03600). This mosaic image uses high-resolution Galileo images of Culann (200 meters or 660 feet per picture element) from the November 1999 flyby and high-resolution images of Tohil (165 meters or 540 feet per picture element) from the February 2000 flyby, and combines them with lower-resolution color images (1.4 kilometers or 0.9 mile per picture element) taken during the July 1999 flyby. Using the combined information, Galileo scientists have identified relationships among many colorful features in this complex.
The volcano Culann has produced both dark black and dark red lava flows, as well as diffuse, inner and outer rings of red and yellowish sulfur particles from explosive plumes (for example, PIA02502). Molten silicate rock inside Culann must occasionally mix with subsurface reservoirs of sulfur and sulfur dioxide to produce the plume deposits. The green color at the center of Culann and inside the older volcano Tohil Patera (center right) forms when red sulfur plume deposits land on dark black silicate lava flows and form a green veneer. The large white patch in southwestern Tohil Patera is rich in sulfur dioxide, and comparison with higher-resolution views (for example, PIA03527) suggests that this might be a region of cold sulfur dioxide flows. The small white patches on the mountain Tohil Mons might be deposits of sulfur dioxide snow that accumulate in grooves and at the bases of steep slopes in colder areas on the mountain. At upper right is a global view of Io showing the location of the mosaic.
Although Tohil Mons rises up to 6 kilometers (19,700 feet) above Io's plains, it is difficult to see in this image because the Sun was behind Galileo at the time it was taken. The topography of the mountainous region is clearer in a mosaic of images taken when the Sun was low in the sky, with illumination from the right (see figure below) The side-lit mosaic combines a high-resolution (330 meters or 1,100 feet per picture element) image from October 2001 with lower-resolution color images (1.4 kilometers or 0.9 mile per picture element) from July 1999.
North is to the top of all images.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA03885: Io's Culann-Tohil Region in Color sur le site de la NASA.
Brightly glowing lava from the volcano Pele is seen in this image taken by NASA's Galileo spacecraft as it receded from its close flyby of Jupiter's moon Io in October, 1999. The image at left shows Io's surface in approximately true color, centered on the large red ring of sulfur that was deposited by Pele's plume and reaches more than 1,300 kilometers (808 miles) in diameter. A false color infrared composite of the same region is shown on the right. The dark red dot at the center of the ring (seen in the false color picture) is the glow of hot lava at the heart of the volcano. Temperatures up to 1,027 degrees Celsius (1,880 degrees fahrenheit) have been previously measured for Pele's lava. The glow is bright enough to be imaged in daylight, allowing scientists to precisely pinpoint the eruptive center.
The region imaged is centered on 18 degrees south, 255 degrees west, and is almost 2,000 kilometers (1,243 miles) across. North is toward the top right of the picture and the sun illuminates the surface from the west.
Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page athttp://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01063: Voyager-to-Galileo Changes, Io's Anti-Jove Hemisphere sur le site de la NASA.
This pair of images depicts the magic worked by JPL engineers to repair radiation damage to images taken by NASA's Galileo spacecraft camera during an October 10 close flyby of Jupiter's volcanic moon Io.
The majority of the Io images acquired by Galileo that day were taken in a camera mode in which 2x2 blocks of picture elements are supposed to be added together during readout of the image from the detector. Because the environment around Io has very high radiation, this mode was implemented to provide additional protection against corruption of the images due to radiation-induced noise. However, apparently due to accumulated radiation damage to the camera electronics, this readout mode did not function properly during the flyby. The effect was that the right and left sides of the images were added together during readout, rather than adjacent pairs of picture elements. This produced something akin to a double-exposed image.
Engineers figured out how the images had been garbled by carefully examining the images and the way the detector readout is commanded. Until recently, it was thought that repair of the images would be impossible. However, an innovative technique has just been developed at JPL for separating the two halves without introducing excessive errors. The scrambled raw data were unscrambled by a program developed using the LabVIEW software from National Instruments of Austin, TX. The image recovery results have been amazing. They allow for reliable analysis of the surface morphologies seen in the Io images.
The image shown here (left: -- original scrambled image; right -reconstructed image) covers a portion of the lava flows emanating from avolcanic center on Io named Zamama. The intricate, convoluted margins of the flows are characteristic of "pahoehoe" (smooth, ropy) lava flows seen on Earth, and provide information on how the lava erupted and advanced over the ground.
North is to the lower left of the picture and the Sun illuminates the surface from the lower left. The image, centered at 17.7 degrees latitude and 172.2 degrees longitude, covers an area approximately 16 by 16 kilometers (10 by 10 miles). The finest details that can be discerned in this picture are about 80 meters (260 feet) across. The image was taken on October 10, 1999 at a range of 1,800 kilometers (1,100 miles) by Galileo's onboard camera.
The Jet Propulsion Laboratory, Pasadena, CA, manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology in Pasadena. This image and other images and data received from Galileo are posted at http://solarsystem.nasa.gov/galileo/ Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
This image, taken by NASA's Galileo spacecraft, shows a new blue-colored volcanic plume extending about 100 kilometers (about 60 miles) into space from Jupiter's moon Io (see inset at lower left). The blue color of the plume is consistent with the presence of sulfur dioxide gas and 'snow' condensing from the gas as the plume expands and cools. Galileo images have also shown that the Ra Patera plume glows in the dark, perhaps due to the fluorescence of sulfur and oxygen ions created by the breaking apart of sulfur dioxide molecules by energetic particles in the Jovian magnetosphere. The images at right show a comparison of changes seen near the volcano Ra Patera since the Voyager spacecraft flybys of 1979 (windows at right show Voyager image at top and Galileo image at bottom). This eruptive plume is an example of a new type of volcanic activity discovered during Voyager's flyby in 1979, believed to be geyser-like eruptions driven by sulfur dioxide or sulfur gas erupting and freezing in Io's extremely tenuous atmosphere. Volcanic eruptions on Earth cannot throw materials to such high altitudes. Ra Patera is the site of dramatic surface changes. An area around the volcano of about 40,000 square kilometers, area about the size of New Jersey, has been covered by new volcanic deposits. The image was taken in late June 28, 1996 from a distance of 972,000 kilometers (604,000 miles). The Galileo mission is managed by NASA's Jet Propulsion Laboratory.
Voir l'image PIA00293: Eruption on Io sur le site de la NASA.
This montage compares similar sides of Io photographed by the Galileo spacecraft in October 1999 (left) and the New Horizons spacecraft on February 27, 2007. The New Horizons image was taken with its Long Range Reconnaissance Imager (LORRI) from a range of 2.7 million kilometers (1.7 million miles).
Most features on Io have changed little in the seven-plus years between these images, despite continued intense volcanic activity. The largest visible feature is the dark oval composed of deposits from the Pele volcano, nearly 1,200 kilometers (750 miles) across its longest dimension. At high northern latitudes, the volcano Dazhbog is prominent as a dark spot in the New Horizons image, near the edge of the disk at the 11 o'clock position. This volcano is much less conspicuous in the Galileo image. This darkening happened after this 1999 Galileo image but before Galileo took its last images of Io in 2001.A more recent change, discovered by New Horizons, can be seen in the southern hemisphere (circled). A new volcanic eruption near 55 degrees south, 290 degrees west has created a roughly circular deposit nearly 500 kilometers (300 miles) in diameter that was not seen by Galileo. Other New Horizons images show that the plume that created this deposit is still active.The New Horizons image is centered at Io coordinates 8 degrees south, 269 degrees west.The first images returned to Earth by New Horizons during its close encounter with Jupiter feature the Galilean moon Io, snapped with the Long Range Reconnaissance Imager (LORRI) at 0840 UTC on February 26, while the moon was 2.5 million miles (4 million kilometers) from the spacecraft.
Io is intensely heated by its tidal interaction with Jupiter and is thus extremely volcanically active. That activity is evident in these images, which reveal an enormous dust plume, more than 150 miles high, erupting from the volcano Tvashtar. The plume appears as an umbrella-shaped feature of the edge of Io's disk in the 11 o'clock position in the right image, which is a long-exposure (20-millisecond) frame designed specifically to look for plumes like this. The bright spots at 2 o'clock are high mountains catching the setting sun; beyond them the night side of Io can be seen, faintly illuminated by light reflected from Jupiter itself.
The left image is a shorter exposure -- 3 milliseconds -- designed to look at surface features. In this frame, the Tvashtar volcano shows as a dark spot, also at 11 o'clock, surrounded by a large dark ring, where an area larger than Texas has been covered by fallout from the giant eruption.
This is the clearest view yet of a plume from Tvashtar, one of Io's most active volcanoes. Ground-based telescopes and the Galileo Jupiter orbiter first spotted volcanic heat radiation from Tvashtar in November 1999, and the Cassini spacecraft saw a large plume when it flew past Jupiter in December 2000. The Keck telescope in Hawaii picked up renewed heat radiation from Tvashtar in spring 2006, and just two weeks ago the Hubble Space Telescope saw the Tvashtar plume in ultraviolet images designed to support the New Horizons flyby.
Most of those images will be stored onboard the spacecraft for downlink to Earth in March and April.
This is the highest resolution color picture taken so far of Jupiter s volcanic moon Io by NASA s Galileo spacecraft. At 3 kilometers (about 2 miles) per picture element, the fiery satellite is seen against a backdrop of Jupiter's cloud tops, which appear blue in this false-color composite. Among the surprises seen on the moon s surface are several small, distinctly greenish patches and subtle violet hues at the cores and margins of bright sulfur dioxide-rich regions (like the one in the lower right). Dark spots, many flagged by bright red pyroclastic deposits, (deposits from explosive ejecta), mark the sites of current volcanic activity. Most of Io's riotous color is due to the presence of sulfur compounds, but the dark materials that make up the flows and calderas are probably silicate rock.
North is to the top of the picture. The images used to construct this composite were taken in the 1- micron, green and violet filters of the solid state imaging camera system on NASA's Galileo spacecraft. The images were taken on March 29, 1998 at a range of 294,000 kilometers (about 183,000 miles).
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.
Voir l'image PIA01604: Close-up color view of Io sur le site de la NASA.
Light from the setting Sun falls across the Loki volcanic region on Jupiter's moon Io in this image taken by NASA's Galileo spacecraft on Oct. 16, 2001.
The image was taken to examine the relative depths and heights of features in the region. The Sun illuminates the surface from the right. Galileo's camera caught the large volcanic crater, or "patera" of Loki near the boundary between night and day. The image also shows several smaller craters plus shadows cast by the high peaks of several mountains.
Shadows cast by the low sun should reveal any topography associated with Loki, such as a plateau in the center of the patera or high patera walls. The near absence of shadows in this region surprised Galileo scientists, as they had expected much more pronounced topography near Loki.
Another surprising aspect of this image is that features that have been black in previous Voyager and Galileo images of Loki, such as the dark lava flows inside the patera, are here brighter than their surroundings. The best explanation is that the shiny, glassy surfaces of chilled lava flows look extremely dark when the Sun is directly overhead, but they reflect the Sun's light comparatively well when it shines at a low angle, in a similar manner to the reflective surfaces of bodies of water. Other volcanic paterae in this image show the same unusual reflectance as seen at Loki. Some of them are being viewed at such an angle that these reflections from lava flows are the brightest features in the image. This image tells us that lava flows on Io chill quickly and form glassy surfaces, not unlike recently cooled lava flows in Hawaii.
The image has a resolution of 1.1 kilometers (0.7 miles) per picture element. North is to the top of the picture.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA03530: Galileo's Best View of Loki Volcano on Io sur le site de la NASA.
This false-color infrared image of the Sunlit disk of Jupiter's moon Io was taken at the NASA Infrared Telescope Facility at Mauna Kea, Hawaii, a few hours after a November 25, 1999 close Io flyby by NASA's Galileo spacecraft. The bright spot at the 1 o'clock position is the same lava fountain seen close-up by Galileo's camera, but in this case it is seen from Earth at a distance of 630 million kilometers (390 million miles).
When this image was taken, the fiery lava fountain was almost on the edge of Io's disk and about to disappear from view due to Io's rotation. The lava fountain was seen from an angle just 5.5 degrees above horizontal. Its prominence when seen so obliquely confirms that this eruption is indeed composed of fiery fountains rising up above the surface; horizontal lava flows would be much harder to see from so close to the horizontal.
Astronomers making Earth-based telescopic observations see a bright spot like this one somewhere on Io only about 20 percent of the time, so the Galileo team was fortunate to catch one in its narrow field of view. Astronomer John Spencer, who has watched this type of eruption for many years on Io from Mauna Kea, said, "We thought that some of these eruptions might be due to lava fountains, but it's incredible to see that idea confirmed so spectacularly by Galileo."
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
New Horizons took this image of Jupiter's volcanic moon Io with its Long Range Reconnaissance Imager (LORRI) at 15:15 Universal Time on February 28, 2007, nearly 10 hours after the spacecraft's closest approach to Jupiter. The image is centered at Io coordinates 5 degrees south, 92 degrees west, and the spacecraft was 2.4 million kilometers (1.5 million miles) from Io. Io's diameter is 3,640 kilometers (2,262 miles).
Io's dayside was deliberately overexposed in this image to bring out details on the nightside and in any volcanic plumes that might be present. Io cooperated by producing an enormous plume, 330 kilometers (200 miles) high, from the volcano Tvashtar. Near Io's north pole, Tvashtar was active throughout New Horizons' Jupiter encounter.In this image, volcanic debris from the plume, illuminated by the setting sun, rains down onto Io's nightside. Hot, glowing lava at the source of the plume is the bright point of light on the sunlit side of the terminator (the line separating day and night). Elsewhere along the terminator, mountains catch the setting sun. The nightside of Io is lit up by light reflected from Jupiter.This image of Jupiter's moon Io and its surrounding sky is shown in false color. It was taken at 5 hours 30 minutes Universal Time on Nov. 9, 1996 by the solid state imaging (CCD) system aboard NASA's Galileo spacecraft, using a clear filter whose wavelength range was approximately 400 to 1100 nanometers. This picture differs in two main ways from the green-yellow filter image of the same scene which was released yesterday.
First, the sky around Io is brighter, partly because the wider wavelength range of the clear filter lets in more scattered light from Io's illuminated crescent and from Prometheus' sunlit plume. Nonetheless, the overall sky brightness in this frame is comparable to that seen through the green-yellow filter, indicating that even here much of the diffuse sky emission is coming from the wavelength range of the green-yellow filter (i.e., from Io's Sodium Cloud).
The second major difference is that a quite large roundish spot has appeared in Io's southern hemisphere. This spot -- which has been colored red -- corresponds to thermal emission from the volcano Pele. The green-yellow filter image bears a much smaller trace of this emission because the clear filter is far more sensitive to those relatively long wavelengths where thermal emission is strongest.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/galileo/sepo.
Voir l'image PIA01109: Io's Sodium Cloud (Clear Filter) sur le site de la NASA.
Two tall volcanic plumes and the rings of red material they have deposited onto surrounding surface areas appear in images taken of Jupiter's moon Io by NASA's Galileo and Cassini spacecraft in late December 2000 and early January 2001.
A plume near Io's equator comes from the volcano Pele. It has been active for at least four years, and has been far larger than any other plume seen on Io, until now. The other, nearer to Io's north pole, is a Pele-sized plume that had never been seen before, a fresh eruption from the Tvashtar Catena volcanic area.
The observations were made during joint studies of the Jupiter system while Cassini was passing Jupiter on its way to Saturn. The two craft offered complementary advantages for observing Io, the most volcanically active body in the solar system. Galileo passed closer to Io for higher-resolution images, and Cassini acquired images at ultraviolet wavelengths, better for detecting active volcanic plumes.The Cassini ultraviolet images, upper right, reveal two gigantic, actively erupting plumes of gas and dust. Near the equator, just the top of Pele's plume is visible where it projects into sunlight. None of it would be illuminated if it were less than 240 kilometers (150 miles) high. These images indicate a total height for Pele of 390kilometers (242 miles). The Cassini image at far right shows a bright spot over Pele's vent. Although the Pele hot spot has a high temperature, silicate lava cannot be hot enough to explain a bright spot in the ultraviolet, so the origin of this bright spot is a mystery, but it may indicate that Pele was unusually active.
Also visible is a plume near Io's north pole. Although 15 active plumes over Io's equatorial regions have been detected in hundreds of images from NASA's Voyager and Galileo spacecraft, this is the first image ever acquired of an active plume over a polar region of Io. The plume projects about 150 kilometers (about 90 miles) over the limb, the edge of the globe. If it were erupting from a point on the limb, it would be only slightly larger than a typical Ionian plume, but the image does not reveal whether the source is actually at the limb or beyond it, out of view.
A distinctive feature in Galileo images since 1997 has been a giant red ring of Pele plume deposits about 1,400 kilometers (870 miles) in diameter. The Pele ring is seen again in one of the new Galileo images, lower left. When the new Galileo images were returned this month, scientists were astonished to see a second giant red ring on Io, centered around Tvashtar Catena at 63 degrees north latitude. (To see a comparison from before the ring was deposited, see PIA01604 or PIA02309.) Tvashtar was the site of an active curtain of high-temperature silicate lava imaged by Galileo in November 1999 and February 2000 (image PIA02584). The new ring shows that Tvashtar must be the vent for the north polar plume imaged by Cassini from the other side of Io! This means the plume is actually about 385 kilometers (239 miles) high, just like Pele. The uncertainty in estimating the height is about 30 kilometers (19 miles), so the plume could be anywhere from 355 to 415 kilometers (221 to 259 miles) high.
If this new plume deposit is just one millimeter (four one-hundredths of an inch) thick, then the eruption produced more ash than the 1980 eruption of Mount St. Helens in Washington.
NASA recently approved a third extension of the Galileo mission, including a pass over Io's north pole in August 2001. The spacecraft's trajectory will pass directly over Tvashtar at an altitude of 200 kilometers (124 miles). Will Galileo fly through an active plume? That depends on whether this eruption is long-lived, like Pele, or brief, and it also depends on how high the plume is next August. Two Pele-sized plumes are inferred to have erupted in 1979 during the four months between Voyager 1 and Voyager 2 flybys, as indicated by new Pele-sized rings in Voyager 2 images. Those eruptions, both from high-latitude locations, were shorter-lived than Pele, but their actual durations are unknown. Before its August flyby, Galileo will get another more-distant look at Tvashtar in May.
It has been said that Io is the heartbeat of the Jovian magnetosphere. The two giant plumes evidenced in these images may have had significant effects on the types, density and distribution of neutral and charged particles in the Jupiter system during the joint observations of the system by Galileo and Cassini from November 2000 to March 2001.
These Cassini images were acquired on Jan. 2, 2001, except for the frame at the far right, which was acquired a day earlier. The Galileo images were acquired on Dec. 30 and 31, 2000. Cassini was about 10 million kilometers (6 million miles) from Io, ten times farther than Galileo.
More information about the Cassini and Galileo joint observations of the Jupiter system is available online at http://www.jpl.nasa.gov/jupiterflyby.
Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo and Cassini missions for NASA's Office of Space Science, Washington, D.C.
This image shows the Chaac region, on Jupiter's moon Io, viewed by two instruments on NASA's spacecraft Galileo during the flyby on February 22, 2000. On the left is an image taken by Galileo's onboard camera. On the right is a map of the relative abundance of sulphur dioxide obtained from an observation made by the infrared spectrometer, an instrument onboard Galileo. The right map shows that the bright white material inside the small caldera just to the east of Chaac (lower right in the camera image) is filled by sulphur dioxide. This sulphur dioxide is purer than at any other location so far observed on Io. It may represent a frozen layer of sulphur dioxide ice on the floor of the caldera. The width of the image seen on the right map is about 100 kilometers (62 miles).
The Jet Propulsion Laboratory, Pasadena, Calif., manages the mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://solarsystem.nasa.gov/galileo/gallery/index.cfm.
Voir l'image PIA02559: Sulphur Dioxide on the Chaac Region of Io sur le site de la NASA.
North is to the top of the picture and the sun illuminates the surface from the left. The image covers an area about 2800 kilometers wide and the smallest features that can be discerned are 4.1 kilometers in size. This image was taken on November 6th, 1996, at a range of 403,100 kilometers by the Solid State Imaging (CCD) system on the Galileo Spacecraft.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01107: Geologic Landforms on Io (Area 5) sur le site de la NASA.
This is a montage of New Horizons images of Jupiter and its volcanic moon Io, taken during the spacecraft's Jupiter flyby in early 2007. The Jupiter image is an infrared color composite taken by the spacecraft's near-infrared imaging spectrometer, the Linear Etalon Imaging Spectral Array (LEISA) at 1:40 UT on Feb. 28, 2007. The infrared wavelengths used (red: 1.59 µm, green: 1.94 µm, blue: 1.85 µm) highlight variations in the altitude of the Jovian cloud tops, with blue denoting high-altitude clouds and hazes, and red indicating deeper clouds. The prominent bluish-white oval is the Great Red Spot. The observation was made at a solar phase angle of 75 degrees but has been projected onto a crescent to remove distortion caused by Jupiter's rotation during the scan. The Io image, taken at 00:25 UT on March 1st 2007, is an approximately true-color composite taken by the panchromatic Long-Range Reconnaissance Imager (LORRI), with color information provided by the 0.5 µm ("blue") and 0.9 µm ("methane") channels of the Multispectral Visible Imaging Camera (MVIC). The image shows a major eruption in progress on Io's night side, at the northern volcano Tvashtar. Incandescent lava glows red beneath a 330-kilometer high volcanic plume, whose uppermost portions are illuminated by sunlight. The plume appears blue due to scattering of light by small particles in the plume
This montage appears on the cover of the Oct. 12, 2007, issue of Science magazine.
Images taken at different times and from different positions by NASA's Galileo spacecraft provide information about the three-dimensional structure of a large mountain named Tohil Mons on Jupiter's moon Io.
The first part of this image package is a mosaic combining detailed images that were taken a year ago by Galileo on Feb. 22, 2000, with a lower-resolution image of a wider area taken on June 30, 1999. The sharper portion has a resolution of 165 meters (540 feet) per picture element. The lower-resolution context image is at 1.3 kilometers (0.8 mile) per picture element. North is to the top of the image. The Sun was almost directly behind the spacecraft, so shadows aren't visible.
Because topography is difficult to distinguish on Io unless the Sun is low enough to cast shadows, the second part of this release is a stereo image of Tohil Mons that was created from two mosaics acquired on Oct.11, 1999, and Feb. 22, 2000. When viewed with red-blue glasses, it illustrates the three-dimensional shape of the mountain and two nearby volcanic depressions, which are called paterae. The largest patera lies along the northeastern margin of the mountain. The stereo observation reveals that the smaller patera with the dark floor is surrounded by mountainous walls. The black lines are areas where data were not acquired.
To the southeast of the peak, many bright lines trending northwest-southeast can be seen. Since the two individual images were taken when the Sun was quite high, it was difficult to determine the relationship between the bright material and the topography. The stereo image reveals that the light material is concentrated at the bases of cliffs. This series of cliffs appears step-like, which may indicate layering in Io's crust.
Two additional figures describing the three-dimensional shape of the Tohil Mons region are also included. The first of these is a topographic representation of what Tohil Mons looks like when seen from the northeast. The topography has been vertically exaggerated. The peak's height is about 5.4 kilometers, plus or minus 1.1 kilometer (about 18,000 feet, give or take 3,600 feet).
The second figure shows two views in which Tohil Mons has been outlined in red. The top image was taken at low resolution and a low Sun angle during Galileo's third orbit, in 1996. Because the Sun is low, topographic features on the mountain can be recognized from the shadows they cast. The two paterae and the peak of the mountain are labeled. The bottom image was taken on Feb. 22, 2000, at higher resolution and a higher Sun angle. The topography is almost indistinguishable, but many more details can be discerned. By combining several observations in this manner, Galileo scientists are able to study Io's mountains and to learn about their evolution and their relationship to Io's volcanoes.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://solarsystem.nasa.gov/galileo/gallery/index.cfm.
Voir l'image PIA02586: Tohil Mons, Io sur le site de la NASA.
The margin of the lava flow field associated with the Prometheus volcanic plume on Jupiter's moon Io is seen in this image, acquired by NASA's Galileo spacecraft on February 22, 2000. The image has a resolution of 12 meters (39 feet) per picture element. The dark lava has margins similar to those formed by fluid lava flows on Earth. This entire area is under the active plume of Prometheus, which is constantly raining bright material. Hence, Galileo scientists interpret the darkest flows as being the most recent. They are not yet covered by bright plume fallout and perhaps too warm for bright gas rich in sulphur dioxide to condense.
The older plains (upper right) are covered by ridges with an east-west trend. These ridges may have formed by the folding of a surface layer or by deposition or erosion. Bright streaks across the ridged plains emanate from the lava flow margins, perhaps where the hot lava vaporizes sulphur dioxide. The bright material must be ejected at a low angle because it only coats the lava-facing sides of the ridges. North is slightly to the right of straight up.
The Jet Propulsion Laboratory, Pasadena, Calif., manages the mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology, Pasadena, Calif.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://solarsystem.nasa.gov/galileo/gallery/index.cfm.
Voir l'image PIA02557: Lava Flows and Ridged Plains at Prometheus, Io sur le site de la NASA.
An active volcanic eruption on Jupiter's moon Io was captured in this image taken on February 22, 2000 by NASA's Galileo spacecraft. Tvashtar Catena, a chain of giant volcanic calderas centered at 60 degrees north, 120 degrees west, was the location of an energetic eruption caught in action in November 1999. A dark, "L"-shaped lava flow to the left of the center in this more recent image marks the location of the November eruption. White and orange areas on the left side of the picture show newly erupted hot lava, seen in this false color image because of infrared emission. The two small bright spots are sites where molten rock is exposed to the surface at the toes of lava flows. The larger orange and yellow ribbon is a cooling lava flow that is more than more than 60 kilometers (37 miles) long. Dark, diffuse deposits surrounding the active lava flows were not there during the November 1999 flyby of Io.
This color mosaic was created by combining images taken in the near-infrared, clear, and violet filters from Galileo's camera. The range of wavelengths is slightly more than that of the human eye. The mosaic has been processed to enhance subtle color variations. The bright orange, yellow, and white areas at the left of the mosaic use images in two more infrared filters to show temperature variations, orange being the coolest and white the hottest material. This picture is about 250 kilometers (about 155 miles) across. North is toward the top and illumination from the Sun is from the west (left).
The Jet Propulsion Laboratory, Pasadena, Calif., manages the mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
North is to the top of the picture which merges images obtained with the clear, red, green, and violet filters of the solid state imaging (CCD) system on NASA's Galileo spacecraft. . The resolution is 8.3 kilometers per picture element. The image was taken on June 27, 1997 at a range of 817,000 kilometers by the solid state imaging (CCD) system on NASA's Galileo spacecraft.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA00740: Topography of Io (color) sur le site de la NASA.
North is to the top of the picture. The resolution is 8.3 kilometers per picture element. The image was taken on June 27, 1997 at a range of 817,000 kilometers by the solid state imaging (CCD) system on NASA's Galileo spacecraft.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01217: Topography of Io sur le site de la NASA.
JPL manages and controls the Voyager project for NASA's Office of Space Science.
Voir l'image PIA01485: South Polar Region of Io sur le site de la NASA.
This global view of Jupiter's moon, Io, was obtained during the tenth orbit of Jupiter by NASA's Galileo spacecraft. Io, which is slightly larger than Earth's moon, is the most volcanically active body in the solar system. In this enhanced color composite, deposits of sulfur dioxide frost appear in white and grey hues while yellowish and brownish hues are probably due to other sulfurous materials. Bright red materials, such as the prominent ring surrounding Pele, and "black" spots with low brightness mark areas of recent volcanic activity and are usually associated with high temperatures and surface changes. One of the most dramatic changes is the appearance of a new dark spot (upper right edge of Pele), 400 kilometers (250 miles) in diameter which surrounds a volcanic center named Pillan Patera. The dark spot did not exist in images obtained 5 months earlier, but Galileo imaged a 120 kilometer (75 mile) high plume erupting from this location during its ninth orbit.
North is to the top of the picture which was taken on September 19, 1997 at a range of more than 500,000 kilometers (310,000 miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URLhttp://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.
Voir l'image PIA01667: Io's Pele Hemisphere After Pillan Changes sur le site de la NASA.
This image of Jupiter's moon Io and its surrounding sky is shown in false color. The solid state imaging (CCD) system on NASA's Galileo spacecraft originally took two images of this scene, one through a clear filter and one through a green-yellow filter. [Versions of these images have been released over the past 3 days.] This picture was created by: (i) adding green color to the image taken through the green-yellow filter, and red color to the image taken through the clear filter; (ii) superimposing the two resulting images. Thus features in this picture which are purely green (or purely red) originally appeared only in the green-yellow (or clear) filter image of this scene. Features which are yellowish appeared in both filters. North is at the top, and east is to the right.
This image reveals several new things about this scene. For example:
(1) The reddish emission south of Io came dominantly through the clear filter. It therefore probably represents scattered light from Io's lit crescent and Prometheus' plume, rather than emission from Io's Sodium Cloud (which came through both filters).
(2) The roundish red spot in Io's southern hemisphere contains a small yellow spot. This means that some thermal emission from the volcano Pele was detected by the green-yellow filter (as well as by the clear filter).
(3) The sky contains several concentrated yellowish spots which were thus seen at the same location on the sky through both filters (one such spot appears in the picture's northeast corner). These spots are almost certainly stars. By contrast, the eastern half of this image contains a number of green spots whose emission was thus detected by the green-yellow filter only. Since any star visible through the green-yellow filter would also be visible through the clear filter, these green spots are probably artifacts (e.g., cosmic ray hits on the CCD sensor).
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/galileo/sepo.
Voir l'image PIA01111: Io's Sodium Cloud On-Chip Format (Clear and Green-Yellow Filters Superimposed) sur le site de la NASA.
These images of an area called Telegonus Mensa on Jupiter's moon Io, taken by NASA's Galileo spacecraft on Oct. 16, 2001, reveal a complex interplay of geologic processes.
Four small, high-resolution frames (9.6 meters, or 32 feet, per picture element) have been set into the larger context mosaic, which has a resolution of 42 meters (140 feet) per picture element. The illumination is from the upper right and north is to the top of the mosaic.
A fracture runs northwest from the lower right corner of the mosaic into the amphitheater in the center of the frame. A high-resolution image along this fracture reveals that lava has erupted from it.
The amphitheater itself is the site of extensive erosion, as the cliff has slumped southeastward under the influence of Io's gravity. High-resolution frames directly south of the amphitheater show another slumping cliff in detail. Flat tops of massive slump blocks—up to 6 kilometers (3.7 miles) long and 0.5 kilometers (0.3 miles) across—are illuminated by the Sun and cast shadows down the face of the cliff. Based on these shadows, Galileo scientists estimate that the cliff is 1 to 2 kilometers (3300 to 6600 feet) high. Just to the left of center a series of landslides can be seen, the longest of which extends 4 kilometers (2.5 miles).
The mosaic is centered at 21.45 degrees south latitude and 124.8 degrees west longitude and is 67 kilometers (42 miles) across.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://solarsystem.nasa.gov/galileo/gallery/index.cfm.
Voir l'image PIA03528: Collapsing Cliff at Telegonus Mensa, Io sur le site de la NASA.
This image depicts the discovery of sulfur gas in the plume of the Pele volcano on Jupiter's moon Io, as seen by the Hubble Space Telescope in October 1999, during a flyby of Io by NASA's Galileo spacecraft. The main image shows Io passing in front of Jupiter as seen by Hubble's Wide-Field Planetary Camera (WFPC2) in near-ultraviolet light. The small inset shows that when a WFPC2 image at shorter ultraviolet wavelengths is included in a color composite with the near-ultraviolet image, Io's Pele plume appears as a dark smudge off the edge of Io's disk, silhouetted against Jupiter. The larger inset shows data from Hubble's Space Telescope Imaging Spectrograph, which mapped the composition of Pele's plume by analyzing the ultraviolet light from Jupiter which had passed through the plume. The regions shown in yellow were rich in sulfur gas, which was precisely centered over the Pele volcano, whose position is shown along with the edge of Io's disk.
Additional information about the Hubble Space Telescope is available athttp://www.stsci.edu/. Additional information about the Galileo mission is available at http://solarsystem.nasa.gov/galileo/.
A cliff slumps outward in these high-resolution views that NASA's Galileo spacecraft captured the edge of a mountain named Telegonus Mensa on Jupiter's moon Io.
When Galileo flew near the south pole of Io in October 2001, scientist's targeted this cliff to study the process of erosion. Water and wind cause most erosion on Earth, but Io has neither surface water nor an atmosphere. The cliff is slumping due to gravity.
The smaller picture (top) has a resolution of 10 meters (33 feet) per picture element. Galileo's camera took it from a distance of about 1,000 kilometers (620 miles). The larger image (below) sets context with a resolution of 40 meters (131 feet) per picture element and was taken from a distance of about 4,200 kilometers (2,600 miles). North is to the top and the Sun illuminates the surface from the upper right.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://galileo.jpl.nasa.gov/. Background information and educational context for the images can be found at http://solarsystem.nasa.gov/galileo/gallery/io.cfm.
Voir l'image PIA02597: Slumping Cliff on Io in High Resolution sur le site de la NASA.
Volcanic calderas, lava flows and cliffs are seen in this false color image of a region near the south pole of Jupiter's volcanic moon Io. It was created by combining a black and white image taken by NASA's Galileo spacecraft on February 22, 2000 with lower resolution color images taken by Galileo on July 3, 1999. The three black spots (top center and middle left) are small volcanic calderas about 10-20 kilometers (6-12 miles) in size, which are dark because their floors are covered by recent lava flows. Two of these three calderas are surrounded by diffuse dark material, which may have been thrown out of the calderas by explosive eruptions.
The bright, white material is thought to be sulfur-dioxide frost and is concentrated near the cliffs in this image. It may be formed when liquid sulfur dioxide seeps out at the base of mountain scarps, vaporizes into a plume of gas, liquid and solid, and then condenses again on the surface. Part of this process, called sapping, occurs in arid environments on Earth when ground water seeps out at the bases of cliffs. The vaporization and production of plumes is much more dramatic on Io due to the lower gravitational acceleration and especially the very low atmospheric pressure. It may be one of the dominant erosion processes on Io.
The mountain at the center left, named Telegonus Mensae, exhibits a number of ridges parallel to its margins. These ridges have been observed on a number of other Ionian mountains and they suggest that as the mountain ages, it is collapsing outward under the influence of gravity.
The yellow lava flow at the southern end of the image appears to be fed by a dark channel that connects to a dark caldera. This is a likely candidate for a lava flow composed of sulfur (rather than silicate material).
The image is centered at 53.8 degrees south latitude and 117.1 degrees west longitude and north is to the top. The higher resolution image has a resolution of 350 meters (or yards) per picture element and is illuminated from the upper left. It was taken at a range of 34,000 kilometers (21,000 miles). The color images have resolutions of 1.3 kilometers (0.81 miles) per picture element and are illuminated from almost directly behind the spacecraft. They were taken at a distance of about 130,000 kilometers (81,000 miles) by Galileo's onboard camera.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Wonderful colors in a volcanic crater named Tupan Patera on Jupiter's moon Io, as seen in this image from NASA's Galileo spacecraft, show varied results of lava interacting with sulfur-rich materials.
The colorfulness of the image is only slightly enhanced from what the human eye would see on the scene. The red in the image includes a small amount of infrared energy. Tupan Patera, named after a Brazilian thunder god, was seen as an active hot spot in earlier Galileo observations, but those low-resolution views did not show details of volcanic activity. This image taken in October 2001 at a resolution of 135 meters (443 feet) per picture element reveals the complex nature of the crater.
Tupan is now clearly shown to be a volcanic depression, about 75 kilometers (47 miles) across, surrounded by cliffs about 900 meters (3000 feet) tall. In the center is a large area that must be higher than the rest of the crater floor because it has not been covered by the dark lavas. Much of the area is coated with a diffuse red deposit that Galileo scientists believe has condensed from sulfur gas escaping from volcanic vents. The floor of Tupan is covered with a surreal pattern of dark black, green, red, and yellow materials. The black material is recent, still-warm lava. The yellow is presumed to be a mix of sulfurous compounds, and the green appears to form where red sulfur has interacted with the dark lavas. While Galileo scientists have found previous evidence for both molten sulfur and molten rock on Io, this image shows the best evidence to date of chemical reactions taking place between the two.
The intermingled patches of sulfur and lava are difficult to explain. The yellowish sulfur may be melting from within the crater walls over solidified but warm lava. The sulfur may boil away from the areas too hot for liquid sulfur to sit on, leaving patches where the dark lava is still visible.
North is to the top of the image and the Sun illuminates the surface from the upper right.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA02599: Colorful Tupan Patera, Io sur le site de la NASA.
The mottled face of Jupiter's volcanically active moon Io [pronounced 'EYE-oh' or 'EE-OH'], viewed by the camera onboard NASA's Galileo spacecraft, shows dramatic changes since it was seen 17 years ago by the exploratory NASA spacecraft Voyagers 1 and 2. This Galileo image, taken on June 25, 1996 at a range of 2.24 million kilometers (1.4 million miles), is centered on the Media Regio area and shows details of the volcanic regions and colored deposits that characterize Io. North is at the top of the picture and the Sun illuminates the surface from the east (right). The smallest features that can be discerned here are approximately 23 kilometers (14 miles) in size, a resolution comparable to the best Voyager images of this face of Io. Io's surface is covered with volcanic deposits that are thought to contain ordinary silicate rock, along with various sulfur-rich compounds that give the satellite its distinctive color. In the brighter areas the surface is coated with frosts of sulfur dioxide. Dark areas are regions of current or recent volcanic activity. Planetary scientists say many changes are evident in the surface markings since this region of Io was imaged 17 years ago by the Voyager spacecraft. The bright regions near the eastern limb of the moon are much more prominent in the Galileo images than they were previously. Surface details have also changed dramatically in the vicinity of the eruptive volcano Masubi (the large, predominantly white feature seen near the 6 o'clock position in this view). Masubi was discovered as an active volcano during the Voyager encounters of Io in 1979.
Voir l'image PIA00282: Io - Full Disk Centered on Media Regio sur le site de la NASA.
This pair of volcanic features on Jupiter's moon Io represents the longest active lava flow known to exist in our solar system. This image, one of the highest resolution pictures ever taken of Io, was obtained by NASA s Galileo spacecraft on July 3, 1999. That was during Galileo's closest pass by Io since it entered orbit around Jupiter in December 1995.
The volcanic features, Amirani (right side of image) and Maui (to the left, just below the center of the image), were originally thought to be two separate volcanoes. However, Galileo images have shown that Maui is actually the active front of a lava flow that has extended westward from a vent at Amirani for more than 250 kilometers (160 miles). Observations by Galileo's near-infrared mapping spectrometer show a hotspot at Maui, so the lava must still be flowing. Other flows extend northward from the Amirani vent.
White plume deposits encircle the Amirani vent and are likely to be sulfur dioxide-rich vapors that have escaped at the vent, frozen and then snowed out onto the ground. The red deposits from the dark spot southwest of the Amirani vent appear to have been blown away from the stronger Amirani plume. The red material may be produced by a form of sulfur.
Amirani-Maui is more than 250 kilometers (160 miles) long. Such gigantic lava flows are found on Venus, the Earth, the Moon, and Mars. Massive eruptions on the Earth coincide with the times of major extinction events.
The image, in false color, uses the near-infrared, green and violet filters (slightly more than the visible range) of the spacecraft's camera, processed to enhance subtle color variations. North is to the top of the picture, and the Sun illuminates the surface from almost directly behind the spacecraft. This illumination is good for imaging color variations, but poor for imaging topographic shading. The image is centered at 23 degrees north latitude and 118 degrees west longitude. The images were taken at a distance of about 130,000 kilometers (81,000 miles) by Galileo's onboard solid state imaging camera and have a resolution of 1.3 kilometers or 0.8 miles per picture element.
Click on this image to viewThe Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of Caltech.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page athttp://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found athttp://www.jpl.nasa.gov/galileo/sepo.">http://www.jpl.nasa.gov/galileo/sepo.
Dramatic changes have occurred at the volcanically active Pillan Patera region of Jupiter's moon Io over the past three years, as seen in this set of three images taken by NASA¹s Galileo spacecraft.
The image on the left was taken in April 1997. The middle image shows the same area in September 1997 after a huge eruption occurred. The eruption produced the large, dark deposit just above and to the right of the center. The deposit, which is 400 kilometers (250 miles) in diameter, surrounds Pillan Patera and covers part of the bright red ring, which is the deposit from Pele¹s plume.
The image on the right was acquired in July 1999 and is our best view of the region since 1997. It shows changes that have taken place on the surface since the eruption almost two years ago. The red material from Pele, which probably contains some form of sulfur, has started to cover, but has not yet entirely obscured, the dark material around Pillan. This may indicate that the plumes of both Pillan and Pele are still active. This image also shows that a small, unnamed volcano to the right of Pillan has erupted, depositing dark material surrounded by a yellow ring, which is most visible where it covers some of the dark material from Pillan's 1997 eruption.
Some of the color differences between the three images are the effects of different lighting conditions when the images were taken. The apparent change in brightness of the dark feature in the lower left corner (Babbar Patera) and of parts of Pele's red plume deposit, are thought to be due to changes in illumination. However, such illumination changes cannot explain the dramatic changes seen at Pillan.
Filters in red, green, and violet wavelengths were combined to produce these images. The color range is slightly enhanced from what the human eye might see at Io. North is to the top of the picture, and the Sun illuminates the surface from the right on the first image, and from the left for the other two. The images are centered at 19 degrees south latitude and 250 degrees west longitude and cover an area approximately 1,650 kilometers wide and 1,750 kilometers high (1,025 miles and 1,090 miles). The resolution of the images on the left and right is about 12 kilometers (7 miles) per picture element. The middle image has a slightly better resolution of about 5 kilometers (3 miles) per picture element. The images taken on April 4, 1997 were from a range of 600,486 kilometers (375,304 miles) by Galileo¹s camera. The images taken on September 19, 1997, were from a range of 505,628 kilometers (316,017 miles). The July 2, 1999 images were taken from a distance of 585,452 kilometers (365,908 miles).
Click on this image to viewThe Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.">http://www.jpl.nasa.gov/galileo/sepo..
JPL manages the Voyager project for NASA's Office of Space Science.
Voir l'image PIA01530: Volcanic Activity on Io sur le site de la NASA.
Jupiter's moon Io with Pele prominently in view. The inset images are from the Voyager 1 (top) and 2 (bottom) spacecraft using the violet, blue, and orange filters. The large image is from Galileo, using the violet, green, and red filters. The colors in the Galileo image are closer to what the human eye would see. With the filters used in the Solid State Imaging system on Galileo, it is clear now that some of the recent volcanic deposits on Io are indeed very red, a point not resolved by Voyager. Scientists speculate that the red deposits are a form of Sulfur produced in volcanic eruptions on Io. Note the rapid changes seen in the shape of the distal (far from the vent) plume deposits from Pele between Voyagers 1 (April, 1979) and 2 (July, 1979). The Galileo image was obtained by the imaging system on board the spacecraft in June, 1996. North is to the top.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.
Voir l'image PIA00718: Io's Pele Hemisphere sur le site de la NASA.
These four views of Jupiter's moon Io clearly show airborne plumes of gas and dust from two of Io's active volcanoes, Zamama and Prometheus. The bottom row consists of enlargements of the plume areas. The first view (left) depicts the tops of both plumes on Io's bright limb or edge. In the second image, an excellent view of Zamama on the bright limb reveals the umbrella-shaped structure. The third image also shows both plumes as bright spots against Io's illuminated crescent. In the fourth view (right) where the volcanic centers lie beyond the terminator (day-night boundary), the tall plumes are visible because they extend up into sunlight. The plumes have a height of about 100 kilometers (60 miles). Both plumes have been active throughout the Galileo tour of the Jovian system which began in 1996. Zamama, however, is considerably larger and brighter in these images from the spacecraft's eleventh orbit of Jupiter than when imaged previously. Prometheus was also active during 1979 flybys of NASA's Voyager spacecraft. There are two other much fainter plumes that can be detected on the bright limb of the third and fourth images. See if you can find them by changing the brightness levels of the images to enhance the dark regions.
North is to the top of the picture. To make the plumes easier to see, the colors have been enhanced by increasing the brightness at the blue end of the spectrum. Since the images shown were taken over an extended period of time, the resolutions range from 8 to 12 kilometers (5 to 7.5 miles) per picture element. The images were taken on November 7th and 8th, 1997by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft at ranges in excess of 800,000 kilometers (500,000 miles).
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URLhttp://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.
Voir l'image PIA01652: Sequence Showing Active Volcanic Plumes on Io sur le site de la NASA.
This is a high-resolution image of part of Prometheus, an active volcano on Jupiter's volcanic moon Io. The image was taken by NASA's Galileo spacecraft on October 10, 1999, during its close flyby of Io. It shows a volcanic caldera, a large depression formed by the collapse of the ground after a volcanic eruption. Some terrestrial examples of calderas can be found in Hawaii. This image also shows dark lava flows and a strange, lumpy surface covered with sulfur-rich snow. The new image is shown over an earlier, color view.
In earlier, lower resolution images, it appeared that all the dark material at Prometheus comprised a single, long lava flow. The new image shows for the first time that the northeastern end of this dark feature is actually a lava-filled caldera 28 kilometers (17 miles) long and 14 kilometers (9 miles) wide. The underground source of the Prometheus lava is probably beneath this newly discovered caldera.
The lava flows that spill over the west rim of the newly discovered caldera clearly indicate that, at some point in time, the entire caldera was filled with lava. It is not clear whether the lava to the south of the caldera originally erupted within the caldera and flowed out, or if it erupted from a vent in the south and then flowed north into the caldera.
Galileo scientists are intrigued also by the snowfield containing hummocks, seen to the east of the Prometheus caldera. They are currently examining a number of alternative models for their formation. One idea is that the hummocks, or routed knolls, are the results of the supersonic blasts from Io's volcanoes plastering material onto one side of pre-existing lumps on the ground.
The black and white, high-resolution image was taken with a filter that let in only a part of the infrared spectrum close to the visible wavelengths. The "color" of materials in the infrared is an important tool in determining the chemical composition of planetary surfaces. North is to the top of the picture and the sun illuminates the surface from almost behind the spacecraft. The resolution is 120 meters (400 feet) per pixel element. This resolution is more than 10 times better than the previous best view of this region. The image covers an area about 96 kilometers (60 miles) wide and 29 kilometers (18 miles) high. It was taken at a distance of 12,000 kilometers (7,500 miles) from Io by the camera onboard Galileo.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://galileo.jpl.nasa.gov/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/images/images.html.
Detail of one of the calderas, or collapsed volcanic craters, on Jupiter's moon Io, is seen in these images acquired on February 22, 2000by NASA's Galileo spacecraft. Taken from a distance of 700 to 800 kilometers (roughly 400 to 500 miles). The five partial images on the right comprise all of the data that could be returned from an eight-image mosaic. These are the highest resolution images of lava flows ever obtained from Io. The resolution of the close-up images varies from 7 to 8 meters (about 23 to 26 feet) per picture element. The boxes in the image to the left are approximate locations of the five partial images. They are shown superimposed on a lower resolution image of the entire Chaac caldera.
The high-resolution snapshots highlight areas from both the southern and northern rims as well as areas on the floor of the caldera. They reveal fascinating similarities and differences between calderas on Io and Earth.
Most puzzling is the texture of the material above the caldera rim. The plains surrounding Chaac are covered with alternating dark and light patches. The process that forms this surface is a complete mystery. By comparison, scientists analyzing the images say the floor of the caldera is amazingly familiar. The interwoven domes and pits form a surface essentially identical to many terrestrial calderas that erupt fluid lavas. For example, the similarity to the caldera on top of the Kilauea Volcano in Hawaii is striking.
The southernmost Chaac image shows several raised plateaus and a deep, dark pit about 400 meters (about 440 yards) across. Although the Kilauea caldera is 10 times smaller than the Chaac caldera, the 1959 Kilauea eruption formed similar features to Chaac when a small volcanic crater was filled by erupting lava. The Hawaiian lava formed a pond that crusted over and then partially drained back down into the ground. Pieces of the pond crust that were left behind formed a perched plateau, and the hole the lava drained back into formed a deep pit. Scientists presume the same thing happened at Chaac in the recent past.
The high-resolution images were taken at a distance of about 700-800 kilometers (400-500 miles) and are centered around 12 degrees north latitude and 158 degrees west longitude. North is to the top and the sun illuminates the surface from the right. The lower resolution image was also taken on February 22, 2000 but from a distance of 18,800 kilometers (11,700 miles) from Io. The image is centered at 11.6 degrees north latitude and 157.7 degrees west longitude. North is to the top and the Sun illuminates the surface from the left.
The Jet Propulsion Laboratory, Pasadena, Calif., manages the mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology, Pasadena, Calif.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://solarsystem.nasa.gov/galileo/gallery/index.cfm.
Voir l'image PIA02551: Snapshots of Chaac: Io's calderas up close sur le site de la NASA.
North is to the top of the picture and the sun illuminates the surface from the left. The image covers an area about 2390 kilometers wide and the smallest features that can be discerned are 3.0 kilometers in size. This image was taken on November 6th, 1996, at a range of 294,000 kilometers by the Solid State Imaging (CCD) system on the Galileo Spacecraft.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01106: Geologic Landforms on Io (Area 4) sur le site de la NASA.
This beautiful image of the crescents of volcanic Io and more sedate Europa is a combination of two New Horizons images taken March 2, 2007, about two days after New Horizons made its closest approach to Jupiter. A lower-resolution color image snapped by the Multispectral Visual Imaging Camera (MVIC) at 10:34 universal time (UT) has been merged with a higher-resolution black-and-white image taken by the Long Range Reconnaissance Imager (LORRI) at 10:23 UT. The composite image shows the relative positions of Io and Europa, which were moving past each other during the image sequence, as they were at the time the LORRI image was taken.
This image was taken from a range of 4.6 million kilometers (2.8 million miles) from Io and 3.8 million kilometers (2.4 million miles) from Europa. Although the moons appear close together in this view, a gulf of 790,000 kilometers (490,000 miles) separates them. Io's night side is lit up by light reflected from Jupiter, which is off the frame to the right. Europa's night side is dark, in contrast to Io, because this side of Europa faces away from Jupiter.
Here Io steals the show with its beautiful display of volcanic activity. Three volcanic plumes are visible. Most conspicuous is the enormous 300-kilometer (190-mile) high plume from the Tvashtar volcano at the 11 o'clock position on Io's disk. Two much smaller plumes are also visible: that from the volcano Prometheus, at the 9 o'clock position on the edge of Io's disk, and from the volcano Amirani, seen between Prometheus and Tvashtar along Io's terminator (the line dividing day and night). The Tvashtar plume appears blue because of the scattering of light by tiny dust particles ejected by the volcanoes, similar to the blue appearance of smoke. In addition, the contrasting red glow of hot lava can be seen at the source of the Tvashtar plume.
The images are centered at 1 degree North, 60 degrees West on Io, and 0 degrees North, 149 degrees West on Europa. The color in this image was generated using individual MVIC images at wavelengths of 480, 620 and 850 nanometers. The human eye is sensitive to slightly shorter wavelengths, from 400 to 700 nanometers, and thus would see the scene slightly differently. For instance, while the eye would notice the difference between the yellow and reddish brown colors of Io's surface and the paler color of Europa, the two worlds appear very similar in color to MVIC's longer-wavelength vision. The night side of Io appears greenish compared to the day side, because methane in Jupiter's atmosphere absorbs 850 nanometer light and makes Jupiter-light green to MVIC's eyes.
Voir l'image PIA10103: Io and Europa Meet Again sur le site de la NASA.
This image, acquired by NASA's Galileo spacecraft on February 22, 2000, is the highest resolution image ever taken of Io. The resolution is 5.2 meters (18 feet) per picture element.
Galileo viewed the surface obliquely, tilted 72 degrees from straight overhead. Illumination is from the lower right, but the topographic shading is difficult to see because of the strong contrasts in brightness of the surface materials. The bright areas are generally higher in elevation than adjacent dark areas. The surface appears to have been eroded by an unknown process, in places exposing layers of bright and dark material. Evaporation of solid ice may also play a role in separating the bright and dark materials. North is toward the upper right.
Also shown is a version of this image processed to give a bird's-eye view over the terrain. This image maps out the true distribution of bright and dark surface materials.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA02556: Highest-Resolution Picture of Io sur le site de la NASA.
Color images from orbit C9 have been merged with a high resolution mosaic of images acquired in various orbits to enhance the surface detail. PIA00703 is another version of this image which also includes detailed insets of the plumes.
North is to the top of the picture. The resolution is about 2 kilometers (1.2 miles) per picture element. This composite uses images taken with the green, violet, and near-infrared filters of the Solid State Imaging (CCD) system on NASA's Galileo spacecraft. The C9 images were obtained on June 28, 1997 at a range of more than 600,000 kilometers (372, 000 miles).
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.
Voir l'image PIA01081: Color Mosaic and Active Volcanic Plumes on Io sur le site de la NASA.
The mosaic covers an area of about 8 million square kilometers, and the finest details that can discerned are about 2.5 kilometers in size. North is to the top of the picture and the sun illuminates the surface from the left. The images which form this mosaic were obtained through the clear filter of the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft on Nov. 6, 1996 (Universal Time) at a range which varied from 245,719 kilometers to 403,100 kilometers.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01108: Mosaic of Io sur le site de la NASA.
Powerful volcanoes and the previous day's sunshine warm the nighttime surface of Jupiter's moon Io, as seen in this image from NASA's Galileo spacecraft.
The left-hand frame shows the best view that Galileo has yet provided of Io's nighttime temperatures. For reference, the right hand frame, based on Galileo camera images, shows the same hemisphere of Io in visible light. The thin bright crescent indicates the only observable portion illuminated by sunlight during the temperature measurements. Several volcanoes are identified on both images: L-K is Lei-Kung Fluctus, L is Loki, Pi is Pillan, M is Marduk, and Pe is Pele.
The temperature map comes from observations by Galileo's photopolarimeter-radiometer instrument during the spacecraft's 27th orbit of Jupiter, in February 2000. Blue indicates the coldest temperatures, near 90 degrees Kelvin (minus 297 degrees Fahrenheit), while oranges and yellows indicate the highest temperatures, in excess of 170 K (minus 153 F). Small areas of the volcanoes are far hotter than this, exceeding 1,500 K (2,240 F). However, in this relatively low-resolution view, which shows no features smaller than about 340 kilometers (210 miles) across, radiation from these small, hot regions is mixed with radiation from surrounding colder regions, so the high temperatures are not detected directly. The observation was made without a filter, so it measures the total heat radiation from Io's night side at all wavelengths.
Much of the heat comes from a few discrete volcanoes. The brightest is Loki, which radiates roughly 15 percent of Io's total volcanic heat, and would appear much brighter still were it not for severe foreshortening due to its position near the edge of the disk. Second brightest is Pillan, where the heat is radiated by extensive cooling lava flows produced largely by an eruption witnessed by Galileo in June 1997 and later. In contrast, although the volcano Pele spouts Io's largest plume, which produces the large orange ring seen in the right-hand image, Pele emits very little total heat. This is because Pele's activity, though vigorous, is confined to a small volcanic crater, where there is no room for large, warm lava flows to radiate heat.
The cooler regions, shown in blues and purples, are dominated by radiation from the surface between the volcanoes, which was warmed by sunlight the previous day and retains some of that heat through the night. Because high-latitude regions receive less sunlight during the day, we would expect them to be cooler at night, but the image shows that temperature varies little with latitude, which is puzzling. Perhaps excess volcanic heat is radiated at the poles, or the polar regions are composed of surface materials that cool off less at night than the materials at lower latitudes. Also, viewing the poles from this angle preferentially presents slopes that were tilted towards the Sun during the day, and thus received more sunlight than the average surface, and this effect might also contribute to the apparent warmth near the poles. The photopolarimeter-radiometer observations of the polar regions on subsequent Io flybys may clear up this mystery.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/.
Voir l'image PIA02589: Io's Nighttime Heat sur le site de la NASA.
Changes in the volcanoes on Jupiter's moon Io can be seen in these three views, taken by NASA's Galileo spacecraft during its three flybys of Io in October 1999, November 1999 and February 2000.
All the images show the active volcanoes as bright yellow, corresponding to hot lava flows that appear glowing in infrared wavelengths. The three views were taken by the spacecraft's near-infrared mapping spectrometer instrument and show the comparison of a typical low-resolution observation to the high-resolution views. The regional observations taken during the recent Io flybys are superimposed on an image taken during Galileo in 1996.
The Prometheus volcano is seen near the middle of all three images. Before the recent flybys, only Prometheus and three other volcanoes were known to be active in this region. After these and other high-resolution observations, scientists were able to detect 14 volcanoes in the same area. The fainter volcanoes (hot spots) show some significant changes over intervals of 1 to 3 months. The area shown by all three observations put together is about 2 million square kilometers (about 770,000 square miles) and covers about 5 percent of Io's surface.
The Jet Propulsion Laboratory, Pasadena, Calif., manages the mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://solarsystem.nasa.gov/galileo/gallery/index.cfm.
Voir l'image PIA02558: Myriad of Hot Spots on Io sur le site de la NASA.
During its 14th orbit of Jupiter in March 29, 1998, NASA's Galileo spacecraft captured an image of Jupiter's moon, Io, that has the same lighting geometry that will exist during Io's close Io flyby on October 11, 1999 (the 24th orbit). The spacecraft groundtrack on Io is shown, with two-minute intervals marked by X's. The large X marks the location of closest approach, when Galileo will be just 500 kilometers (about 300 miles) above Io's surface. The curved boundary on the left marks the "terminator" or boundary between the lit day side and dark night side. Although the Pele volcano will be on the night side during the flyby, the hot lavas will be seen glowing in the dark. Other targets of interest that will be visible near closest approach are Pillan Patera, the site of dramatic surface changes, Reiden Patera, Marduk, the bright plains of Colchis regio, and the rugged Dorian Montes mountains. Active volcanic plumes and high-temperature hot spots have been seen at Pele, Pillan, and Marduk.
North is to the top of this image, which has a resolution of 2.6 kilometers (1.6 miles) per picture element. The image was taken at a range of 256,948 kilometers (about 160,000 miles) by the solid state imaging camera system on NASA's Galileo spacecraft.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, D.C.
This image and other images and data received from Galileo are posted on the World Wide Web on the Galileo mission home page at URL http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.
Voir l'image PIA01605: Io imaging during Galileo's 24th orbit sur le site de la NASA.
The source area of what had been a towering volcanic plume two months earlier lies in the far-right frame of this mosaic of images taken of Jupiter's moon Io by NASA's Galileo spacecraft on Oct. 16, 2001.
The region in the images includes the Zamama lava flow in Jupiter's northern hemisphere. The Zamama flow field emanates from the northernmost of two small volcanoes in the far left frame. These lava flows were not present in Voyager images of Io, so they formed some time between the Voyager 1 flyby in 1979 and the first Galileo observations of Io in 1996. Galileo also observed Zamama during Io encounters in 1999, and scientists identified narrow, long, dark lava flows thought to be similar to lava flows in Hawaii.
Moving northeast, the second and third frames of this mosaic contain lava flow fields and several unnamed volcanic depressions, called "paterae." It is unclear whether the broad, shield-like features or plateaus on which the paterae rest were created by eruptions from the paterae, or if they were preexisting features. Some fractures and dark lines suggest that the crust here is breaking up, creating cracks that magma can use to rise to the surface.
The far-right frame of this mosaic shows dark lava flows and bright spots. The bright spots are probably sulfur-bearing plume deposits, which are thought to be associated with the source of a plume eruption 500 kilometers (310 miles) high that was observed by the Galileo spacecraft in August, 2001. It was the largest plume eruption ever observed on Io.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA03531: New plume vent near Zamama, Io sur le site de la NASA.
These false-color images of Io and Jupiter were taken with the NASA Infrared Telescope Facility at Mauna Kea, Hawaii, as part of a campaign to support closeup Io observations by NASA's Galileo spacecraft. These and other Earth-based observations show that Io's most powerful volcano, Loki, began one of its periodic major eruptions about a month before Galileo's October Io flyby, and that the eruption was continuing during the Galileo flyby. These infrared images (taken at a wavelength of 3.8 microns) show Sunlight reflected from the edge of Jupiter's disk on the left-hand side, and the heat from several glowing volcanoes on Io on the right. Io is in Jupiter's shadow, so no Sunlight falls on it -- the volcanoes are all we see.
On August 9, 1999 (left), several volcanoes glowed faintly with roughly equal brightness. However, on October 10, 1999, roughly 20 hours before Galileo flew past, a single volcano, Loki, dominated the image. Loki brightened by a factor of ten in the period between these images. Other observations from the NASA Infrared Telescope and from Wyoming Infrared Telescope near Laramie operated by the University of Wyoming show that most of this brightening occurred during September.
Earth-based observations since the 1980s have shown that these periodic bright eruptions are typical behavior for Loki. They occur about once per year and last several months. Galileo has given us our first chance to see one of these eruptions up close.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
North is to the top of the picture. The resolution is about 6 kilometers per picture element (6.1 for the left hand image and 5.7 for the right). The images were taken on April 4th, 1997 at a ranges of 600,000 kilometers (left image) and 563,000 kilometers (right image) by the solid state imaging (CCD) system on NASA's Galileo spacecraft.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01218: Mountains and Plateaus on Io sur le site de la NASA.
Three full-disk color views of Jupiter's volcanic moon Io as seen by NASA's Galileo spacecraft camera are shown in enhanced color (near-infrared-, green-, and violet-filtered images) to highlight details of the surface. Comparisons of these images to those taken by the Voyager spacecraft 17 years ago has revealed many changes have occurred on Io. Since that time, about a dozen areas at least as large as the state of Connecticut have been resurfaced. These three views, taken by Galileo in late June 1996, show about 75 percent of Io's surface. The images reveal that some areas on Io are truly red, whereas much of the surface is yellow or light greenish. The major red areas shown here appear to be closely associated with very recent fragmental volcanic deposits (pyroclastics) erupted in the form of volcanic plumes. The most prominent red oval surrounds the volcano Pele (far right), as previously discovered by Hubble Space Telescope images. An intense red spot lies near the active plume Marduk east of Pele. Other reddish areas are associated with known hot spots or regions that have changed substantially since the Voyager spacecraft flybys of 1979. The reddish deposits may be the products of high-temperature explosive volcanism. There are some curious differences in the overlap region between the images at left and center. There are several especially bright areas in the image at left that appear much darker in the image at center. These may represent transient eruptions or surface materials with unusual light-scattering properties. Several volcanic plumes active during the Voyager flybys in 1979 occurred near the bright limbs or terminator regions of these images, where airborne materials should be detectable. Loki and Amirani appear to be inactive, Volund is active, and Pele may be active but is extremely faint. The plume Marduk also seems to be active, and dark jets of erupting materials can be seen against the disk. Several previously unknown mountains can be seen near the terminators. The Galileo mission is managed by NASA's Jet Propulsion Laboratory.
Voir l'image PIA00292: Three Views of Io sur le site de la NASA.
This image of Io eclipsed by Jupiter's shadow is a combination of several images taken by the New Horizons Long Range Reconnaissance Imager (LORRI) between 09:35 and 09:41 Universal Time on February 27, 2007, about 28 hours after the spacecraft's closest approach to Jupiter. North is at the top of the image.
In the darkness, only glowing hot lava, auroral displays in Io's tenuous atmosphere and the moon's volcanic plumes are visible. The brightest points of light in the image are the glow of incandescent lava at several active volcanoes. The three brightest volcanoes south of the equator are, from left to right, Pele, Reiden and Marduk. North of the equator, near the disk center, a previously unknown volcano near 22 degrees north, 233 degrees west glows brightly. (The dark streak to its right is an artifact.)The edge of Io's disk is outlined by the auroral glow produced as intense radiation from Jupiter's magnetosphere bombards the atmosphere. The glow is patchy because the atmosphere itself is patchy, being denser over active volcanoes. At the 1 o'clock position the giant glowing plume from the Tvashtar volcano rises 330 kilometers (200 miles) above the edge of the disk, and several smaller plumes are also visible as diffuse glows scattered across the disk. Bright glows at the edge of Io on the left and right sides of the disk mark regions where electrical currents connect Io to Jupiter's magnetosphere.New Horizons was 2.8 million kilometers (1.7 million miles) from Io when this picture was taken, and the image is centered at Io coordinates 2 degrees south, 238 degrees west. The image has been heavily processed to remove scattered light from Jupiter, but some artifacts remain, including a horizontal seam where two sets of frames were pieced together. Total exposure time for this image was 56 seconds.The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01065: Lack of visible change around active hotspots on Io sur le site de la NASA.
The patera, or depression, is quite large: 106.3 kilometers (66 miles) by 115.0 kilometers (71 miles). Galileo has detected volcanic activity at this site in the past, particularly in late 1996.
Galileo took this image on Oct. 16, 2001, during its 32nd orbit of Jupiter. Effects of a new eruption at Gish Bar can be seen in a comparison with images from 1999 (see figure below). The new eruption was first detected in infrared imaging by Galileo's near-infrared mapping spectrometer in August 2001. This visible-light image shows a pair of new lava flows. The largest runs to the western boundary and extends to the central and northern portions of the patera. The other flow corresponds to a secondary depression in the southeastern portion of the patera. Based on changes seen at this depression between July and October 1999, this is thought to be the site of an outburst seen by Earth-based observers in August 1999.
Gish Bar Patera lies at the base of an 11-kilometer (36,000-foot) mountain at 15.6 degrees north latitude, 89.1 degrees west longitude on Io. This image was taken from a distance of 25,000 kilometers (15,500 miles) and has a resolution of 250 meters (820 feet) per pixel. The Sun is straight behind the observer, an illumination angle that minimizes shadows and emphasizes inherent brightness variations rather than topography.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA03884: Recent Eruption at Gish Bar Patera on Io sur le site de la NASA.
The volcano Pele glows in the night in this close-up image of Jupiter's moon Io, obtained by NASA's Galileo spacecraft in the closest-ever Io flyby on October 10, 1999. Only surfaces hotter than 600 degrees Celsius (1,100 degrees Fahrenheit) are visible in this image. The hot material forms a thin, curving line more than 10 kilometers (6 miles) long and up to 50 meters (150 feet) wide. Galileo scientists believe that the changes in brightness along the curving line are due to variations in the amount of hot lava exposed at the surface. Data acquired previously suggest that the liquid lava at Pele is over 1,200 degrees Celsius (2,200 degrees Fahrenheit). Such lava would cool and become invisible in this image in just a few minutes. Therefore, this image outlines parts of the volcano that are at most a few minutes old.
The outline of the fresh, hot material is superimposed on the best daytime image of Pele (bottom), showing that the hot material follows the margin of Pele's caldera. A caldera is a depression caused by collapse during a volcanic eruption. Galileo scientists hypothesize that the Pele caldera is filled with liquid lava, with the floating crust broken-up along the margins where it hits the cliffs along the caldera's walls. The lava lake is probably confined to the dark, southern part of the Pele caldera, which covers an area of about 15 by 10 kilometers (10 by 6 miles). Previous data collected by Galileo indicate that hot material covers only an area of about 800 by 800 meters (0.5 by 0.5 miles). This suggests that most of the lava lake is covered by a cooler crust that floats on top of the molten lava. The behavior of this lava lake is similar to that of Hawaiian lava lakes, although Pele covers an area several thousand times larger than the lakes in Hawaii. Interestingly, the image of Pele's caldera obtained by Galileo in October shows only about one-percent of thehot area was known to be on the volcano. This indicates that 99-percent of the activity at Pele is in a region that was not imaged in this flyby.
North is to the top of the picture and the sun is on the other side of Io. It is centered at 18.6 degrees south latitude and 255.7 degrees west longitude, looking obliquely at an area approximately 10 kilometers (6 miles) by 10 kilometers (6 miles) in size. The picture has a resolution of 30 meters (100 feet) per picture element and is taken in the clear filter using a 45.8 millisecond exposure time. The images were taken by the camera onboard Galileo from a range of about 1,400 kilometers (840 miles).
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page athttp://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
This eerie view of Jupiter's moon Io in eclipse (left) was acquired by NASA's Galileo spacecraft while the moon was in Jupiter's shadow. Gases above the satellite's surface produced a ghostly glow that could be seen at visible wavelengths (red, green, and violet). The vivid colors, caused by collisions between Io's atmospheric gases and energetic charged particles trapped in Jupiter's magnetic field, had not previously been observed. The green and red emissions are probably produced by mechanisms similar to those in Earth's polar regions that produce the aurora, or northern and southern lights. Bright blue glows mark the sites of dense plumes of volcanic vapor, and may be places where Io is electrically connected to Jupiter.
The viewing geometry is shown in the image on the right. North is to the top of the picture, and Jupiter is towards the right. The resolution is 13.5 kilometers (8 miles) per picture element. The images were taken on May 31, 1998 at a range of 1.3 million kilometers (800,000 miles) by Galileo's onboard solid state imaging camera system during the spacecraft's 15th orbit of Jupiter.
JPL manages the Galileo mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web on the Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.
Voir l'image PIA01637: Io's Aurorae sur le site de la NASA.
A hot, active volcanic crater named Camaxtli Patera (large feature to the right) is shown in this image of Jupiter's moon Io taken by NASA's Galileo spacecraft on February 22, 2000.
A patera is a large depression, probably of volcanic origin, but also affected by cracks and faults in Io's crust. There appear to be both bright and dark lava flows on the patera floor. The dark lava flows are likely to have cooled from super-hot, magnesium-rich, silicate lava of the type that existed on Earth billions of years ago. The bright patches may be much cooler, sulfur-rich lava flows. Bright deposits can also be seen just outside of Camaxtli, and there is a halo of diffuse dark material that extends up to 30 kilometers (19 miles) from the rim of the patera. This halo is probably made up of frozen droplets of lava that rained down after they were blasted into the sky from vents in Camaxtli.
Two smaller paterae, which are unnamed, are to the left (west) of Camaxtli. One has very dark, very fresh lava on the floor and is hotter than the larger Camaxtli Patera because it is erupting lava at a faster rate. The other is comparatively bright, like the surrounding plains. This implies that the volcanism here has been dormant for long enough that snow and frost have covered the lava flows.
The surrounding plains are mottled and appear to be topographically rough. The lumpy texture of the ground around Camaxtli appears to be a common feature of the frozen plains of Io. The Sun is almost directly overhead (actually 12 degrees to the south), so most of the brightness variations in this image are due to different types of surface materials rather than topographic shading. The image resolution is 186 meters (204 yards) per picture element and the scene width is 145 kilometers (91 miles). The center of the image is located at about 15 north latitude, 138 west longitude.
The Jet Propulsion Laboratory, Pasadena, Calif., manages the mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
This composite of images, all acquired by NASA's Galileo spacecraft, contains three views at three different image resolutions of the volcano Prometheus on Jupiter's moon Io. The upper mosaic consists of eight high-resolution frames (12 meters or 39 feet per picture element). The lower left image is a single medium-resolution frame (170 meters or 186 yards per picture element); and the lower right mosaic consists of several low-resolution color frames (1.3 kilometers or .81 miles per picture element).
The high- and medium-resolution frames were obtained during Galileo's third close flyby of Io, on February 22, 2000, while the low-resolution color context frames were obtained on June 30, 1999. In all the images, north is to the top, and the high-resolution mosaic spans about 65 kilometers (40 miles) from east to west. The high-resolution mosaic is centered at about 13 degrees north latitude and 155 degrees west longitude.
At increasing resolution, more surface details about Prometheus become clear. For example, dark spots visible on flows of Prometheus at lower resolution resolve into dark, fresh lava flows with well-defined margins at higher resolution. Bright spots along the margins of Prometheus resolve into bright streaks that appear to come from plumes emanating from the edges of the Prometheus flows. The terrain surrounding Prometheus, which appears relatively smooth at lower resolution, resolves into a complex material composed of rough, ridge-like features at higher resolution. Also visible in the rightmost frame of the high-resolution mosaic (on the northern edge of the very dark lava flow in the lower right corner) are two bright spots, which may indicate active, glowing lava breakouts.
The Jet Propulsion Laboratory, Pasadena, Calif., manages the mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena.
This image, other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA02564: Io's Prometheus Volcano at Various Resolutions sur le site de la NASA.
This image of Jupiter's moon Io, taken by NASA's Galileo spacecraft on November 25, 1999, shows a bright lava flow with a distinct dark channel in the middle. This type of winding channel is a common sight on shallow slopes in lava flows on Earth that are moving fairly quickly. The serrated margins are characteristic of fluid lava that is able to work its way into every available nook and crevice. What is unusual about this lava flow is its bright color -- most lava flows on Io and the other planets are dark. This leads Galileo scientists to speculate that these lava flows are composed of sulfur, rather than silicate rock. The lava flow appears to emanate from a caldera named Emakong, which is just beyond the left edge of the picture.
North is to the upper left of the picture and the Sun illuminates the surface from almost behind the spacecraft. The image, centered at -3.7degrees latitude and 117.4 degrees longitude, covers an area approximately 120 by 40 kilometers (75 by 25 miles). The resolution is 150 meters (500 feet) per picture element. The image was taken at a range of 15,000 kilometers (9,400 miles) by the camera onboard Galileo.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology in Pasadena.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
North is to the top of the picture which combines images acquired using violet, green, and near-infrared (756 micrometers) filters. The resolution is 11.2 kilometers per picture element. The images were taken on February 20, 1997 at a range of 554,000 kilometers by the solid state imaging (CCD) system on NASA's Galileo spacecraft.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01223: Changes on Io's Loki-Pele hemisphere sur le site de la NASA.
Composite view of Amalthea and Io at the same scale. The visible part of Amalthea is about 150 kilometers across. The colors are approximate. Amalthea is actually much darker than Io, but is displayed at a similar brightness for ease of viewing. The shape of Amalthea is controlled largely by impact cratering and fragmentation. In contrast, Io, like Earth, has gravity sufficient to form it into a slightly ellipsoidal sphere. Amalthea is covered by craters because there are no processes which erode or cover them efficiently. On extremely volcanically active Io, impact craters are covered quickly by lavas and other volcanic materials. Some of the volcanic materials escape from Io and probably contribute to the reddish colors of Amalthea and the other small inner satellites.
The Amalthea and Io composites, obtained by the solid state imaging (SSI) camera on NASA's Galileo spacecraft on different orbits, were placed side by side for comparison purposes. The Amalthea composite combines data taken with the clear filter of the SSI system during orbit six, with lower resolution color images taken with the green, violet, and 1 micrometer filters during orbit 4. The Io data was obtained on July 2nd, 1998 (orbit 14) using the green, violet, and 1 micrometer filters.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo.">http://www.jpl.nasa.gov/galileo/sepo.
These frames detail the changes around Pele on Jupiter's moon Io, as seen by Voyager 1 (left), Voyager 2 (middle), and Galileo (right). The Voyager frames were taken in 1979 when the two spacecraft flew past Jupiter and it's moon Io. The Galileo view was obtained in June, 1996. Note the changes in the shape of the deposits further from the vent while the radial dark features closer to the vent show little change. The Voyager images use orange, blue, and violet filters. The Galileo image uses the green and violet filters of the Solid State Imaging system aboard the Galileo spacecraft and a synthetic blue. All three images are in a simple cylindrical projection and are approximately 1700 km x 1500 km. North is to the top.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.
Voir l'image PIA00717: Pele Comparisons Since 1979 sur le site de la NASA.
Click on this image for a full resolution context image (in tiff format) that corresponds to the caption below. Click here for a jpeg format image.
The highest resolution image ever of Jupiter's volcanic moon Io, (the black and white image at top), was taken by NASA's Galileo spacecraft on October 10, 1999, from an altitude of 617 kilometers (417 miles). It shows an area about 7.2 kilometers (4.5 miles) long and 2.2 kilometers (1.4 miles)wide. Features as small as 9 meters (30 feet) can be discerned, providing a resolution which is 50 times better the previous best, taken by the Voyager spacecraft in 1979.
The box drawn in the center image, a Galileo image of Io taken earlier in the mission, shows the area displayed in the new image at top. The three color images below show the volcanic region from a much higher altitude than the other images and follow a volcanic eruption observed by Galileo earlier in mission
This new image targeted lava flows that erupted from the volcano Pillan. A complex mix of smooth and rough areas can be seen with clusters of pits and domes, many of which are the size of houses. The volcanic features are similar to those found on Earth and Mars. However, this combination of different types of lava flows has not been seen before in such a small area, demonstrating the variety of volcanic processes that continue to change the surface of Io.
North is to the top of the pictures and the Sun illuminates the surface from the right. In the top and middle images the Sun is only a few degrees above the horizon, emphasizing topography. Galileo scientists estimate that the cliff on the left side of the image ranges from 3 to 10 meters (10 to 33 feet) high.
In 1997 Galileo caught Pillan in the process of erupting. The explosion blanketed an area 400 kilometers (250 miles) in diameter with ash as seen in the series of three color images at the bottom. These images show the changes that have occurred at Pillan over the last three years (previous release). Pillan is the new dark spot in middle color frame and the big, red ring seen in all three images is formed by the plume from the nearby volcano Pele. Galileo's camera and near-infrared mapping spectrometer measured the temperatures of the lavas during the eruption and found that they were hotter than any known eruption on Earth in the last two billion years.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/galileo. Background information and educational context for the images can be found at URLhttp://www.jpl.nasa.gov/galileo/sepo
Voir l'image PIA02507: Highest Resolution Image Ever Obtained of Io sur le site de la NASA.
New Horizons captured this unique view of Jupiter's moon Io with its color camera -- the Multispectral Visible Imaging Camera (MVIC) -- at 00:25 UT on March 1, 2007, from a range of 2.3 million kilometers (1.4 million miles). The image is centered at Io coordinates 4 degrees south, 162 degrees west, and was taken shortly before the complementary Long Range Reconnaissance Imager (LORRI) photo of Io released on March 13 (see PIA09250), which had higher resolution but was not in color.
As in the LORRI picture, this processed image shows the nighttime glow of the Tvashtar volcano and its plume rising 330 kilometers (200 miles) into sunlight above Io's north pole. However, the MVIC picture reveals the intense red of the glowing lava at the plume source and the contrasting blue of the fine dust particles in the plume (similar to the bluish color of smoke), as well as more subtle colors on Io's sunlit crescent. The lower parts of the plume in Io's shadow, lit only by the much fainter light from Jupiter, are almost invisible in this rendition. Contrast has been reduced to show the large range of brightness between the plume and Io's disk.
A component of the Ralph imaging instrument, MVIC has three broadband color filters: blue (480 nanometers), red (620 nm) and infrared (850 nm); as well as a narrow methane filter (890 nm). Because the camera was designed for the dim illumination at Pluto, not the much brighter sunlight at Jupiter, the red and infrared filters are overexposed on Io's dayside. This image is therefore composed from the blue and methane filters only, and the colors shown are only approximations to those that the eye would see. Nevertheless, the human eye would easily see the red color of the volcano and the blue color of the plume.
These views of the key volcanic centers on Jupiter's moon, Io, merge color data with higher resolution mosaics. They show the color units in relation to surface features, and fine brightness variations such as volcanic flows. The images in frames "a" through "g" are all scaled to the same proportions. Frame "a" is 575 kilometers (356 miles) across.
These images show that some of the most colorful and high-contrast regions on Io are associated with the most active volcanoes. They also illustrate that fresh-appearing lava flows are often associated with active plumes(for example at Loki, Prometheus, Culann, Marduk, Volund, Zamama, Maui, and Amirani). It is possible that the plumes result from interaction between the advancing flows and the SO2-rich surface deposits, analogous to the plumes that form when lava flows into a body of water (for example, in Hawaii).
North is to the top of the picture. The color has been enhanced. The images were obtained with the green, violet, and 756 micrometer filters of the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URLhttp://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo
Voir l'image PIA01668: Key Volcanic Centers on Io sur le site de la NASA.
Culann Patera, one of the most colorful volcanic centers on Io, is the centerpiece of this mosaic of the best high-resolution, color view of Io yet returned by NASA's Galileo spacecraft. The picture was constructed from images taken through the red, green, and violet filters of Galileo camera and has been processed to enhance the color variations. The resolution is about 200 meters (or yards) per picture element, and north is to the top.
The color mosaic shows the complex relationships between the diffuse red deposit, the more confined green deposit, and the various colored lava flows. Culanns central caldera (above and to the right of center) has a highly irregular, scalloped margin and a green-colored floor. Lava flows spill out of the caldera on all sides. A dark red, curving line extending northwest from the southwestern tip of the caldera may mark a crusted-over lava tube feeding the dark (and hot) silicate flows to the northwest. Unusual dark red flows to the southeast of the caldera may be sulfur flows or silicate flows whose surfaces have been modified. The diffuse red material around the caldera is believed to be a compound of sulfur deposited from a plume of gas.
Culanns caldera and several lava flows extending from the caldera are coated by greenish materials. Green material can also be seen in the caldera to the lower right of the image, named Tohil Patera. The greenish material often has sharp boundaries, so it is apparently confined to the caldera floor and the dark flows. Galileo scientists are investigating whether the greenish material forms as a coating of sulfur-rich material on warm silicate lavas.
The images were taken on November 25, 1999 during Galileo's 25th orbit at a distance of 20,000 kilometers (12,500 miles) from Io. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Scientists pointed NASA's Galileo spacecraft camera at the Tohil region of Jupiter's moon Io to investigate the curious relationship between Io's mountains and its volcanoes.
This mosaic of Galileo images taken Oct. 16, 2001, shows details of the mountain called Tohil Mons (lower left), a small dark-floored volcanic crater, or "patera," bordered by mountain walls (middle), and intricate patterns of dark lava flows intertwined with bright material on the floor of a larger crater, Tohil Patera (upper right). An earlier stereo observation by Galileo revealed that Tohil Mons rises up to 6 kilometers (19,700 feet) above the surrounding plains. In contrast, shadows in the new images indicate the two paterae are only about 100 meters (330 feet) deep.
The new images were taken soon after sunrise at Tohil, with a resolution of 50 meters (160 feet) per picture element to reveal details never seen before. Another view showing the entire mountain at lower resolution was also acquired.
Despite Io's extremely high rate of volcanic activity, its mountains do not resemble volcanoes seen elsewhere in the solar system. Instead, the mountains appear to be formed by the uplift of large blocks of Io's crust. This image shows evidence of numerous landslides from the mountain (bottom left). However, one of the most surprising revelations from this observation is that despite the closeness of the small, dark-floored patera to the mountain walls, the patera floor is not covered with any landslide debris. This indicates that the patera floor has been resurfaced with lava more recently than any landslides have occurred. Another possibility is that this patera, like others on Io, is actually a lava lake and completely consumes debris that falls into it from the mountain. Galileo's infrared-mapping instrument has detected heat from the patera, indicating an active or very recent eruption.
North is to the top of the picture and the Sun illuminates the surface from the right. The mosaic is centered at 27.5 degrees south latitude and 160 degrees west longitude and covers 280 kilometers (170 miles) from upper right to lower left.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://solarsystem.nasa.gov/galileo/gallery/index.cfm.
Voir l'image PIA03527: Detailed View of Mountain and Craters at Tohil, Io sur le site de la NASA.
Clues about how lava spreads great distances on Jupiter's volcanic moon Io come from high-resolution views taken by NASA's Galileo spacecraft of a lava channel flowing out of Emakong Patera near Io's equator.
The lava channel is dark and runs to the right from the dark patera, or large depression, at the left of this mosaic. The mosaic sets several high-resolution images (30 meters or 100 feet per picture element) into the context of lower-resolution images (150 meters or 490 feet per picture element). Galileo took the high-resolution ones during a close flyby of Io on Oct. 15, 2001. The context images of the Emakong Patera region were acquired during a November 1999 flyby.
The 1999 images showed a dark channel though which molten material once fed a broad, bright lava flow that extended for hundreds of kilometers or miles. Those images raised questions about how lava could travel so far. The new images show that the lava channel is roofed over in several places, indicating that an insulating cover grew over parts of the channel, allowing the lava to move farther before freezing. More puzzling is the intimate mixing of bright and dark material in the lava flow. The liquids might have been a combination of molten rock and sulfur or might have been just sulfur, which has black, red, orange and yellow forms. One possibility is that the material that erupted from the volcano was molten rock that melted an underlying layer of sulfur. The molten sulfur could then have oozed up through the solidifying lava, producing the mottled surface seen here.
North is to the top of the picture. The Sun illuminates the surface from almost directly behind the spacecraft, so the brightness variations in the image are due to differences in the brightness of surface materials, not to shadows. The view is centered at 4.6 degrees south latitude and 117.5 degrees west longitude.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA02598: Lava Channel at Io's Emakong Patera sur le site de la NASA.
Five color views of Jupiter's moon Io, as seen by NASA's Galileo spacecraft camera, were taken between the 25th and the 29th of June, 1996 Universal Time. The color is a composite of the red, green, and violet filters of the on board imaging system with the brightness of the violet bandpass increased to provide better color discrimination. The full disk images were intended for color mapping of Io's surface and for comparison to Voyager images. Where images overlap several features can be seen to change in relative brightness, perhaps due to unusual light scattering behavior or active phenomena. The crescent images were intended primarily for color imaging of active volcanic plumes on the bright limb and these images showed that the Voyager-era Loki plumes were no longer active and revealed a new plume at Ra Patera. The smallest features which can be discerned in the 5 views range from 9 to 23 kilometers and provide our best look at Io since the 1979 Voyager flybys. Sub-spacecraft longitudes on Io (from upper left to lower right) are 69, 338, 264, 211, and 221 W. North is to the top.
Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA00491: Five Color Views of Io sur le site de la NASA.
This mosaic of Tvashtar Catena on Jupiter's moon Io, taken by NASA's Galileo spacecraft on Oct. 16, 2001, completes a series of views depicting changes in the region over a period of nearly two years. A catena is a chain of volcanic craters.
Streaks of light and dark deposits that radiate from the central volcanic crater, or "patera," are remnants of a tall plume that was seen erupting in earlier images.
This image and the others from November 1999, February 2000, December 2000, and August 2001 were all taken to study aspects of this ever-changing, extremely active volcanic field.
Tvashtar is pictured here just 10 months after both the Galileo and Cassini spacecraft observed the eruption of a giant plume of volcanic gas emanating from it. The plume rose 385 kilometers (239 miles) high and blanketed terrain as far as 700 kilometers (435 miles) from its center.
Tvashtar has erupted in a variety of styles over the course of almost two years: (1) a lava curtain 50 kilometers (30 miles) long in the center patera, (2) a giant lava flow or lava lake eruption in the giant patera at far left, and (3) the large plume eruption. Therefore Galileo scientists expected that the lava flow margins or patera boundaries within Tvashtar would have changed drastically. However, the series of observations revealed little modification of this sort, suggesting that the intense eruptions at Tvashtar are confined by the local topography.
North is to the top of the mosaic, which is approximately 300 kilometers(186 miles) across and has a resolution of 200 meters (656 feet) per picture element.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://solarsystem.nasa.gov/galileo/gallery/index.cfm.
Voir l'image PIA03529: Galileo's Last View of Tvashtar, Io sur le site de la NASA.
Current scientific ideas about the role of sulfur in volcanoes on Jupiter's moon Io are illustrated. Sulfur gas consisting of pairs of sulfur atoms (S2), detected above Io's volcano Pele by the Hubble Space Telescope in October 1999, is ejected from the hot vents of Io's volcanoes (green arrow). The sulfur gas lands on the cold surface, where the sulfur atoms rearrange into molecules of three or four atoms (S3, S4), which give the surface a red color. Eventually the atoms rearrange into their most stable configuration, rings of eight atoms (S8), which form ordinary pale yellow sulfur.
Additional information about the Hubble Space Telescope is available athttp://www.stsci.edu/hst/. Additional information about the Galileo mission is available at http://galileo.jpl.nasa.gov.
Voir l'image PIA02547: The Role of Sulfur in Io's Volcanoes sur le site de la NASA.
NASA's Galileo spacecraft acquired the images in this mosaic of Hi-iaka Patera (the irregularly shaped, dark depression at the center of the image) and two nearby mountains on November 25, 1999 during its 25th orbit. The sharp peak at the top of the image is about 11 kilometers (about 36,300 feet) high, and the two elongated plateaus to the west and south of the caldera are both about 3.5 kilometers (11,500 feet) high. The ridges on the northwestern mountain are often seen on Ionian mountains and are thought to be formed as surface material slides downslope due to gravity.
At low resolution, many of the dark features, called pateras, appear to be calderas -- depressions formed by collapse into an empty magma chamber. However, higher resolution images such as this one suggest a different origin. In the case of Hi-iaka, the northern and southern margins of the pateras have very similar shapes which appear to fit together. This may indicate that the crust has been pulled apart here and the resulting depression has subsequently been covered by dark lava flows. Furthermore, the two mountains bordering Hi-iaka Patera also appear to fit together. However, the similar shapes and heights of the pateras margins and mountains could be coincidental. Galileo scientists are currently investigating whether mountains and pateras are related to each other and what could cause the surface of Io to rift apart in such a manner.
North is to the top of the mosaic and the sun is illuminating the surface from the left. The resolution is 260 meters (about 280 yards) per picture element. Galileo took the images at a distance of 26,000 kilometers(16,000 miles) from Io.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA02540: Rifting at Hi'iaka Patera, Io? sur le site de la NASA.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.
Voir l'image PIA00835: NIMS Observation of Hotspots on Io sur le site de la NASA.
The green-yellow filter and clear filter images of Io which were released over the past two days were originally exposed on the same frame. The camera pointed in slightly different directions for the two exposures, placing a clear filter image of Io on the top half of the frame, and a green-yellow filter image of Io on the bottom half of the frame. This picture shows that entire original frame in false color, the most intense emission appearing white.
East is to the right. Most of Io's visible surface is in shadow, though one can see part of an illuminated crescent on its western side. The burst of white light near Io's eastern equatorial edge (most distinctive in the green filter image) is sunlight scattered by the plume of the volcano Prometheus.
There is much more bright light near Io in the clear filter image, since that filter's wider wavelength range admits more scattered light from Prometheus' sunlit plume and Io's illuminated crescent. Thus in the clear filter image especially, Prometheus's plume was bright enough to produce several white spikes which extend radially outward from the center of the plume emission. These spikes are artifacts produced by the optics of the camera. Two of the spikes in the clear filter image appear against Io's shadowed surface, and the lower of these is pointing towards a bright round spot. That spot corresponds to thermal emission from the volcano Pele.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/galileo/sepo.
Voir l'image PIA01110: Io's Sodium Cloud (Clear and Green-Yellow Filters) sur le site de la NASA.
These stunning images of the planetary duo are being released to commemorate the ninth anniversary of the Hubble telescope's launch on April 24, 1990. All of these images were taken with the Wide Field and Planetary Camera 2.
The three overlapping snapshots show in crisp detail Io passing above Jupiter's turbulent clouds. The close-up picture of Io (bottom right) reveal a 120-mile-high (200-kilometer) plume of sulfur dioxide "snow" emanating from Pillan, one of the moon's active volcanoes.
"Other observations have inferred sulfur dioxide 'snow' in Io's plumes, but this image offers direct observational evidence for sulfur dioxide 'snow' in an Io plume," explains John R. Spencer of Lowell Observatory in Flagstaff, Ariz.
A Trip Around Jupiter
The three snapshots of the volcanic moon rounding Jupiter were taken over a 1.8-hour time span. Io is roughly the size of Earth's moon but 2,000 times farther away. In two of the images, Io appears to be skimming Jupiter's cloud tops, but it's actually 310,000 miles (500,000 kilometers) away. Io zips around Jupiter in 1.8 days, whereas the moon circles Earth every 28 days.
The conspicuous black spot on Jupiter is Io's shadow and is about the size of the moon itself (2,262 miles or 3,640 kilometers across). This shadow sails across the face of Jupiter at 38,000 mph (17 kilometers per second). The smallest details visible on Io and Jupiter measure 93 miles (150 kilometers) across, or about the size of Connecticut.
These images were further sharpened through image reconstruction techniques. The view is so crisp that one would have to stand on Io to see this much detail on Jupiter with the naked eye.
The bright patches on Io are regions of sulfur dioxide frost. On Jupiter, the white and brown regions distinguish areas of high-altitude haze and clouds; the blue regions depict relatively clear skies at high altitudes.
These images were taken July 22, 1997, in two wavelengths: 3400 Angstroms (ultraviolet) and 4100 Angstroms (violet). The colors do not correspond closely to what the human eye would see because ultraviolet light is invisible to the eye.
Io: Jupiter's Volcanic Moon
In the close-up picture of Io (bottom right), the mound rising from Io's surface is actually an eruption from Pillan, a volcano that had previously been dormant.
Measurements at two ultraviolet wavelengths indicate that the ejecta consist of sulfur dioxide "snow," making the plume appear green in this false-color image. Astronomers increased the color contrast and added false colors to the image to make the faint plume visible.
Pillan's plume is very hot and its ejecta is moving extremely fast. Based on information from the Galileo spacecraft, Pillan's outburst is at least 2,240 degrees Fahrenheit (1,500 degrees Kelvin). The late bloomer is spewing material at speeds of 1,800 mph (2,880 kilometers per hour). The hot sulfur dioxide gas expelled from the volcano cools rapidly as it expands into space, freezing into snow.
Io is well known for its active volcanoes, many of which blast huge plumes of volcanic debris into space. Astronomers discovered Pillan's volcanic explosion while looking for similar activity from a known active volcano, Pele, about 300 miles (500 kilometers) away from Pillan. But Pele turned out to be peaceful. Io has hundreds of active volcanoes, but only a few, typically eight or nine, have visible plumes at any given time.
Scientists will get a closer look at Io later this year during a pair of close flybys to be performed by NASA's Galileo spacecraft, which has been orbiting Jupiter and its moons for nearly 3-1/2 years.
The first Galileo flyby is scheduled for Oct. 10 at an altitude of 379 miles (610 kilometers), and the other will occur on Nov. 25, when the spacecraft will fly only 186 miles (300 kilometers) above Io's fiery surface. If the spacecraft survives this daring journey into the intense Jovian radiation environment near Io, it will send back images with dramatically higher resolution than any obtained before, according to mission scientists.
The Hubble telescope image of Io's volcanic plume is a composite taken July 5, 1997, in three wavelengths: 2600 Angstroms (ultraviolet), 3400 Angstroms (ultraviolet), and 4100 Angstroms (violet).
Voir l'image PIA01540: Hubble Clicks Images of Io Sweeping Across Jupiter sur le site de la NASA.
Color images acquired on September 7, 1996 have been merged with higher resolution images acquired on November 6, 1996 by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft. The color is composed of data taken, at a range of 487,000 kilometers, in the near-infrared, green, and violet filters and has been enhanced to emphasize the extraordinary variations in color and brightness that characterize Io's face. The high resolution images were obtained at ranges which varied from 245,719 kilometers to 403,100 kilometers.
Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA00583: High Resolution Global View of Io sur le site de la NASA.
Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA00584: Global View of Io in various colors sur le site de la NASA.
Voyager 1 image of Io showing active plume of Loki on limb. Heart-shaped feature southeast of Loki consists of fallout deposits from active plume Pele. The images that make up this mosaic were taken from an average distance of approximately 490,000 kilometers (340,000 miles).
Voir l'image PIA00010: Io with Loki Plume on Bright Limb sur le site de la NASA.
The detailed structure near the volcano Loki is like nothing seen elsewhere on Io. When this Voyager 1 picture was taken, the main eruptive activity came from the lower left of the dark linear feature (perhaps a rift) in the center. Below is the "lava lake," a U-shaped dark area about 200 kilometers across. In this specially processed image, detail can be seen in the dark surface of this feature, possibly due to "icebergs" of solid sulfur in a liquid sulfur lake. The IRIS on Voyager 1 found this "lava lake" to be the hottest region on Io, with a temperature about 150 degrees Celsius higher than that of the surrounding area.
Voir l'image PIA00375: Io - Volcano Loki and Loki Patera sur le site de la NASA.
A volcano named Zamama on Jupiter's moon Io has recently changed in appearance as seen in this pair of images of Io acquired by NASA's Galileo spacecraft as it approached Io in preparation for a close flyby.
The false color images use the near-infrared, green and violet filters (a range greater than the range the human eye can see) of the spacecraft's camera, processed to slightly enhance Io's naturally vibrant colors. The image on the left was acquired in March 1998 during Galileo's 14th orbit and the image on the right was collected in July 1999 during the 21st orbit. The July 1999 images are the highest resolution images of Io taken by Galileo since it entered orbit around Jupiter in December 1995.
Zamama formed during the time period between the flybys of NASA's Voyager spacecraft in 1979 and Galileo's first images of Io taken in 1996. Based on these images, Galileo scientists suspect that the dark lava is erupting from a crack in the ground. Analysis of combined data from Galileo's camera and its near-infrared mapping spectrometer instrument showed that the lava erupting at Zamama must be hotter than 830 C (1,500 F). Because this too hot to be sulfur, scientists believe the lava may contain silicates.
The most dramatic difference between these two images is that the volcanic plume that was active in March 1998 and earlier had stopped erupting by July 1999. The rising core of the umbrella-shaped plume can be seen in the 1998 image as a bluish spot in the center of the dark lava. Dark and bright spokes of material falling away from the core are also visible. When it falls back to the ground, this material makes circular white and yellow deposits around the vent. The white deposits are thought to be composed mostly of sulfur dioxide that left the volcanic vent as a vapor and condensed into a frost as the gases expanded into the near-vacuum of Io's atmosphere. Interestingly, red plume material has only been deposited to the northwest. This might be the result of small pockets of boiling sulfur that produce droplets of red sulfur blown outward by the main plume. Most of the other, more subtle color variations around Zamama are likely to be the result of different lighting conditions that existed when the two images were taken.
A high-resolution (20 to 40 meters or 66 to 130 feet per picture element) strip of images across Zamama is planned during Galileo's flyby of Io on October 10, 1999. These images will be useful in determining how lava moves on Io's surface, specifically whether the lava travels in open rivers of lava or in well-insulated lava tubes. The size and shape of features on the lava flows can be used to estimate properties of the lava that will provide vital clues to the still unanswered question about what kind of lava is erupting from Io's volcanoes.
North is to the top of the pictures. The images are centered at 17.4 degrees north latitude and 173 degrees west longitude. The image on the left was taken on March 1998 at a range of 294,000 kilometers (183,000 miles) and has a resolution of 3 kilometers (2 miles) per picture element. The Sun illuminates the surface from the right. The image on the right was taken in July 1999 at a distance of about 130,000 kilometers (81,000 miles) and has a resolution of 1.3 kilometers or 0.8 miles per picture element. The Sun illuminates the surface from almost directly behind the spacecraft.
Click on this image to viewThe Jet Propulsion Laboratory, Pasadena, CA, manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo
Voir l'image PIA02504: Close-up of Zamama, Io (color) sur le site de la NASA.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01070: Changes on Io between Voyager 1 and Galileo's second orbit around an unnamed vent North of Prometheus sur le site de la NASA.
This set of four images, taken by NASA's Galileo spacecraft, shows a sequence of volcanic activity on Jupiter's moon Io over the last two years. As seen from left to right, the feature called Masubi was observed during Galileo¹s 9th, 10th, 15th, and 22nd orbits of Jupiter. These images show that a plume deposit from Masubi appears in September 1997 and has disappeared eight months later, only to reappear in a different place little more than a year later. The deposit, which originated from a volcanic vent, contains snow rich in sulfur dioxide.
Plume deposits are formed when material is blown out of a vent in a continuous, geyser-like, high-velocity eruption, with the material then falling back to Io's surface under the influence of gravity. When it hits the surface, it forms a symmetric ring surrounding the plume vent. The plume deposits are transient features, present only while the associated plume is active and for a brief time afterwards. This sequence of images suggests that the plume deposit visible during Galileo¹s 10th orbit was almost completely gone by the time of its 15th orbit, eight months later. This illustrates how ephemeral the deposits are.
Scientists are intrigued by the speed at which the active plume location seems to have migrated. The distance between the centers of the deposits visible in the images from the 10th orbit, second from left, and 22nd orbit, the image on the right, (occurring over a period of less than two years), is about 125 kilometers (78 miles). The plume deposit has changed in size as well as location. The four arrows are the same size and orientation in the images from the 10th and 22nd orbit, showing that the dark ring of material is larger during the 22nd orbit than it was in the 10th orbit.
These images were taken through the violet filter of Galileo¹s camera. North is to the top and the Sun illuminates the surface from the left in the images from June 1997 and August 1999, and from the right in the images from September 1997 and May 1998. The images are centered at 50 degrees south latitude and 54 degrees west longitude and cover an area approximately 750 kilometers (470 miles) wide and 1,050 kilometers (660 miles) high. From left to right, the image resolutions are: 16 kilometers (10 miles), 10 kilometers (6.2 miles), 14 kilometers (8 miles), and, 16 kilometers (10 miles) per picture element.
From left to right, the images were taken by Galileo¹s camera on the following dates from the following distances from Io: June 17, 1997, at 816,500 kilometers (507,300 miles); September 18, 1997, at 1,046,500 kilometers (650,300 miles); May 30, 1998, at 1,398,500 kilometers (869,000 miles); and August 13, 1999, at 1,565,000 kilometers (972,400).
Click on this image to viewThe Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo
Voir l'image PIA02503: Migrating Volcanic Plumes on Io sur le site de la NASA.
This very high resolution (19 meters, or about 21 yards, per picture element) mosaic shows the complex collection of lava flows, pits, domes, and possibly rafted plates of lava on Io. The images were taken by NASA's Galileo spacecraft on October 11, 1999 during its 24th orbit. The observation targeted a 70-kilometer (44-mile) long lava flow that erupted from Pillan Patera in June 1997. Rafted plates like those that appear in this image are also seen on Earth and Mars; they may indicate that the lava was flowing rapidly enough to rip apart the crust as it formed. Galileo scientists believe that most of these lava flows, which cover about 400square kilometers (160 square miles), were emplaced in about two weeks. A shadow that appears to be cast by the edge of an individual lava flow (lower left) indicates that the flow is 10 meters, or yards, thick.
The pits and domes, which range from a few tens of meters to many hundreds of meters in scale, are more difficult to explain. One possibility is that these are the result of interactions between the hot lava and Io's volatile-rich surface. Such vents are observed on Earth when lava flows interact with ground water or ice far from the actual source of the lava.
A joint observation of Pillan on June 27, 1996 by Galileo's onboard camera and near-infrared mapping spectrometer provided a temperature estimate forth lava of 1,900 Kelvins (3,900 degrees Fahrenheit), hundreds of degrees hotter than terrestrial eruptions. Although the lava flows have cooled significantly since then, they were still warm at the time of these observations.
North is to the top of the picture and the Sun illuminates the surface from the right. The images were taken on October 11, 1999 at a distance of 1,900 kilometers (1,200 miles) from Io. The large doses of radiation to which the spacecraft is subjected each time it passes close to Jupiter caused a problem with Galileo's camera, which resulted in scrambling of these images. Engineers at NASA's Jet Propulsion Laboratory, Pasadena, CA, were able to reconstruct the images, but black stripes remain where some data could not be recovered.
JPL manages the mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA02536: 1997 Lava Flows Near Pillan Patera, Io sur le site de la NASA.
Jupiter's four largest satellites, including Io, the golden ornament in front of Jupiter in this image from NASA's Cassini spacecraft, have fascinated Earthlings ever since Galileo Galilei discovered them in 1610 in one of his first astronomical uses of the telescope.
Images from Cassini that will be released over the next several days capture each of the four Galilean satellites in their orbits around the giant planet.
This true-color composite frame, made from narrow angle images taken on Dec. 12, 2000, captures Io and its shadow in transit against the disk of Jupiter. The distance of the spacecraft from Jupiter was 19.5 million kilometers (12.1 million miles). The image scale is 117 kilometers (73 miles) per pixel.
The entire body of Io, about the size of Earth's Moon, is periodically flexed as it speeds around Jupiter and feels, as a result of its non-circular orbit, the periodically changing gravitational pull of the planet. The heat arising in Io's interior from this continual flexure makes it the most volcanically active body in the solar system, with more than 100 active volcanoes. The white and reddish colors on its surface are due to the presence of different sulfurous materials. The black areas are silicate rocks.
Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Office of Space Science, Washington, D.C.
Voir l'image PIA02860: Io in Front of Jupiter sur le site de la NASA.
The Long Range Reconnaissance Imager (LORRI) on New Horizons captured another dramatic picture of Jupiter's moon Io and its volcanic plumes, 19 hours after the spacecraft's closest approach to Jupiter on Feb. 28, 2007. LORRI took this 75 millisecond exposure at 0035 Universal Time on March 1, 2007, when Io was 2.3 million kilometers (1.4 million miles) from the spacecraft.
Io's dayside is deliberately overexposed to bring out faint details in the plumes and on the moon's night side. The continuing eruption of the volcano Tvashtar, at the 1 o'clock position, produces an enormous plume roughly 330 kilometers (200 miles) high, which is illuminated both by sunlight and "Jupiter light."
The shadow of Io, cast by the Sun, slices across the plume. The plume is quite asymmetrical and has a complicated wispy texture, for reasons that are still mysterious. At the heart of the eruption incandescent lava, seen here as a brilliant point of light, is reminding scientists of the fire fountains spotted by the Galileo Jupiter orbiter at Tvashtar in 1999.
The sunlit plume faintly illuminates the surface underneath. "New Horizons and Io continue to astonish us with these unprecedented views of the solar system's most geologically active body" says John Spencer, deputy leader of the New Horizons Jupiter Encounter Science Team and an Io expert from Southwest Research Institute.
Because this image shows the side of Io that faces away from Jupiter, the large planet does not illuminate the moon's night side except for an extremely thin crescent outlining the edge of the disk at lower right. Another plume, likely from the volcano Masubi, is illuminated by Jupiter just above this lower right edge. A third and much fainter plume, barely visible at the 2 o'clock position, could be the first plume seen from the volcano Zal Patera.
As in other New Horizons images of Io, mountains catch the setting Sun just beyond the terminator (the line dividing day and night). The most prominent, seen as a bright vertical line, is the edge of a plateau about 4.5 kilometers (15,000 feet) high, similar in altitude to the Colorado Rockies. Io itself has a diameter of 3,630 kilometers (about 2,250 miles).
The image is centered at Io coordinates 4 degrees S, 165 degrees W. It has been processed to reduce contrast, in order to show details over the full 1000-to-1 brightness range of the original data.
From these eclipse images we see evidence for enhanced concentrations of volcanic gases (dominantly SO2) at the sub- and anti-Jupiter regions. This enhanced degassing may be due directly to the tides or may be due to enhanced heat flow at depth below these regions.
North is to the top of the picture. The eclipse resolutions are 13.2 (left) and 63 (right) kilometers per picture element. The images were taken on September 18, 1997 (left) and October 5, 1997 (right) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.
Voir l'image PIA01094: Io Degassing from sub- and anti-Jupiter Regions sur le site de la NASA.
Backlit views (left pair) show a giant volcanic plume as a bulge on the crescent edge of Jupiter's moon Io, and more fully lit views (right pair) reveal rings where sulfur-rich plume material has fallen back to the ground, in images captured by NASA's Galileo spacecraft in early August 2001.
Io is the most volcanically active world known. Galileo and NASA's Voyager and Cassini spacecraft have caught several of Io's volcanoes in action lofting plumes of gas and particles high above the large moon's surface. However, none of the plumes seen previously has climbed as high as the one evidenced in three of these pictures.
During its Aug. 6, 2001, close encounter with Io, Galileo flew right through a space where a plume from the Tvashtar volcano near Io's north pole had been active when Galileo and Saturn-bound Cassini imaged Io seven months earlier. To see if the Tvashtar plume was still active in August, scientists used Galileo's camera to acquire images when the spacecraft was nearly on the opposite side of Io from the Sun, so that Io appears as a backlit crescent.
Tvashtar's plume did not show up, but another one did, rising from a previously undiscovered and still unnamed volcano about 600 kilometers (370 miles) south of Tvashtar. The left two images are color coded to reveal the faint outer plume. The bright inner plume rises about 150 kilometers (90 miles) high, and the top of the faint outer plume can be detected at 500 kilometers (310 miles) above the surface, making this is the largest plume ever detected on Io. A portion of the plume with intermediate brightness extends north of the eruption's source vent. (The vertical lines, bright spots and short streaks in these two images are noise.)
One of the more fully illuminated color images of Io (second image from right) reveals a bull's-eye ring of new dark and light materials marking the eruption site. No obvious volcanic center had previously been seen at this location, 41 degrees north latitude and 133 degrees west longitude. The bright material of the new plume deposit overlies the red-ring plume deposit encircling the Tvashtar volcano at 63 degrees north, 123 degrees west. Tvashtar's ring deposit was first seen in Galileo images taken in late December 2000.
Another new full-disc color image of Io (far right) reveals yet another new plume deposit near Io's north pole, encircling the Dazhbog Patera volcanic site. This red ring has a diameter of about 1,000 kilometers (620 miles), suggesting a plume height of about 300 kilometers (190 miles). This plume deposit was not present in January 2001, so it is evidence of a new eruption.
Io is about the same size as Earth's Moon. All four images have resolutions of 18 to 20 kilometers (11 to 12 miles) per picture element. Unlabeled versions are also available. Click on the thumbnail versions below.
Infrared imagery from Galileo or Earth-based telescopes has detected intense hot spots at the sites of all three of these giant plumes. Giant polar plumes represent a class of eruption seen by the Voyager spacecraft in 1979, but not during Galileo's first five years of orbiting Jupiter. Voyager was unable to measure temperatures or other properties of these eruptions, so scientists are pleased Galileo has survived long enough to do so. Galileo reached Jupiter in late 1995. Its original two-year orbital mission has been extended three times to take advantage of the spacecraft's continuing capability to return valuable scientific information about the Jupiter system.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/.
Prometheus has displayed similar characteristics such as size, shape and brightness to Galileo's cameras as it did to Voyager's. However, several intriguing differences are also apparent. There appears to be a new dark lava flow emanating from the vent of Prometheus, and the plume is now erupting from a position about 75 kilometers (46.5 miles) west from where the hot spot resided in 1979. It is not known if the plume source is the same or if the plume is now emanating from a new source. Overall, scientists studying Galileo images of Io see that a wide variety of surface changes have occurred on Io since 1979. The Galileo image was taken at a range of about 487,000 kilometers (about 302,000 miles) from Io. The Voyager image was taken from about 800,000 kilometers (about 500,000 miles).
The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http:// www.jpl.nasa.gov/galileo/sepo
Voir l'image PIA00495: Changing volcanoes on Io sur le site de la NASA.
These images illustrate just how quickly the surface of Io is changing. The image on the left shows lava flows from the volcano Prometheus as seen by NASA's Galileo spacecraft on October 11, 1999 on its 24th orbit (I24). White streaks emanating from around the edge of the flow may be frost deposited by small plumes of gas rich in sulfur dioxide that is vaporized by the hot lava. Bright material from the Prometheus plume quickly covers any cool surface; therefore, the darkest areas are the youngest lava flows. The middle image shows the same area as it appeared to Galileo 4-1/2 months later, on February 22, 2000 during its 27th orbit (I27). Numerous changes in the shapes and locations of the dark lava flows and bright streaks are evident.
The image on the right is a ratio of the I27 and I24 images (constructed by dividing the I27 image by the I24 image) which illustrates the changes that occurred between I24 and I27. Anything that became darker between October and February is dark in the ratio image and anything that became brighter is bright in the ratio. The juxtaposition of the dark and bright areas in the ratio image indicates that most of the fresh (dark) flows seen in I27 are extensions of the flows that were fresh (dark) during I24. Approximately 60 square kilometers (23 square miles) were covered by new lava flows in the 134 days between the two images. This means the average rate at which lava is covering the surface is about .45 square kilometers(.18 square miles) per day. This rate for Prometheus is about 10 times higher than peak eruption rates at Kilauea in Hawaii.
North is to the top in all images, and the images have resolutions of about 180 meters (or yards) per picture element. The large doses of radiation to which the spacecraft is subjected each time it passes close to Jupiter caused a problem with Galileo's camera, which resulted in scrambling of the I24 image. Engineers at NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA, were able to reconstruct the image, but a black stripe remains where data could not be recovered. Some areas that could not be reconstructed appear blurred. To avoid a recurrence of this problem, a different camera mode was used during I27, so the later image is fine.
JPL manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
North is to the top of the picture and the sun illuminates the surface from the left. The image covers an area about 2000 kilometers wide and the smallest features that can be discerned are 2.5 kilometers in size. This image was taken on November 6th, 1996, at a range of 245,719 kilometers by the Solid State Imaging (CCD) system on the Galileo Spacecraft.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01105: Geologic Landforms on Io (Area 3) sur le site de la NASA.
New Horizons took this montage of images of Jupiter's volcanic moon Io, glowing in the dark of Jupiter's shadow, as the Pluto-bound spacecraft sped through the Jupiter system on Feb. 27, 2007.
(A): In this picture from the Long-Range Reconnaissance Imager (LORRI), dark blotches and straight lines are artifacts. The brightest spots (including the volcanoes Pele [P] and East Girru [EG]) are incandescent lava from active volcanoes. The more diffuse glows, and the many faint spots, are from gas in the plumes and atmosphere, glowing due to bombardment by plasma in Jupiter's magnetosphere, in a display similar to the Earth's aurorae. (B): The same image with a latitude/longitude grid, showing that the cluster of faint spots is centered near longitude 0 degrees, the point on Io that faces Jupiter. The image also shows the locations of the plumes seen in sunlit images (indicated by red diamonds), which glow with auroral emission in eclipse. (C): Simulated sunlit view of Io with the same geometry, based on sunlit LORRI images. (D): A combination of the sunlit image (in cyan) and the eclipse image (in red), showing that all point-like glows in the eclipse image arise from dark volcanoes in the eclipse image. (E): This infrared image, at a wavelength of 2.3 microns, obtained by New Horizons Linear Etalon Spectral Imaging Array (LEISA) an hour after the LORRI image, showing thermal emission from active volcanoes. Elongation of the hot spots is an artifact. (F): Combined visible albedo (cyan) and LEISA thermal emission (red) image, showing the sources of the volcanic emission. That most of the faint point-like glows near longitude zero, seen in visible light in images A, B, and D, do not appear in the infrared view of volcanic heat radiation, is one reason scientists believe that these glows are due to auroral emission, not heat radiation.
This image appears in the Oct. 12, 2007, issue of Science magazine, in a paper by John Spencer, et al.
This pair of images taken by NASA's Galileo spacecraft captures a dynamic eruption at Tvashtar Catena, a chain of volcanic bowls on Jupiter's moon Io. They show a change in the location of hot lava over a period of a few months in 1999 and early 2000.
The image on the left uses data obtained on Nov. 26 and July 3, 1999, at resolutions of 183 meters (600 feet) and 1.3 kilometers (0.8 miles) per pixel, respectively. The red and yellow lava flow itself is an illustration based upon imaging data.
The image on the right is a composite using a five-color observation made on Feb. 22, 2000, at 315 meters (1030 feet) per pixel. These are among the most fortuitous observations made by Galileo because this style of volcanism is too unpredictable and short-lived to plan to photograph. Short-lived bursts of volcanic activity on Io had been previously detected from Earth-based observations, but interpreting the style of volcanic activity from those lower-resolution views was highly speculative.
These Galileo observations confirm hypotheses that the initial, intense thermal output comes from active lava fountains. Galileo's high-resolution observations of volcanic activity on Io have also confirmed other hypotheses based on earlier, low-resolution data. These include interpretations of slowly spreading lava flows at Prometheus and Amirani and an active lava lake at Pele. These tests of earlier hypotheses increase scientists' confidence in interpreting volcanic activity seen in low-resolution remote sensing data of Earth as well as Io. However, these data are still of insufficient resolution to adequately test the more quantitative models that have been applied to volcanic eruptions on Earth and Io.
These images also show other geologic features on Io, such as the scalloped margins of the plateau to the northeast of the active lavas. These margins appear to have formed by sapping, a process usually associated with springs of water. Liquid sulfur dioxide might be the fluid responsible for sapping on Io. A better understanding of sapping on Io will influence how scientists interpret similar features on Mars(where the viability of carbon dioxide or water as the sapping fluid remains controversial).
The individual images in this composite can be viewed separately in PIA02545 (left hand image) and PIA02550 (right hand image).
The Jet Propulsion Laboratory, Pasadena, Calif., manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology in Pasadena.
Images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://solarsystem.nasa.gov/galileo/gallery/index.cfm.
Images were produced by Brown University, Providence, R.I.,http://www.planetary.brown.edu/, DLR (German Aerospace Center) Berlin,http://www.dlr.de/pf/, and University of Arizona, Tempe, http://www.lpl.arizona.edu/.
Voir l'image PIA02584: Eruption at Tvashtar Catena on Io sur le site de la NASA.
This mosaic of images taken by NASA's Galileo spacecraft on February 22,2000 shows three mountains and two lava-filled depressions in the Shamshu region of Jupiter's moon Io. The dark oval feature on the left side of the image is a depression that has been resurfaced by lava flows. The rough terrain northeast of the depression is Shamshu Mons. A10-kilometer (6-mile) wide canyon oriented in northeast to southwest direction cuts this mountain. The northwestern edge of the mountain has been scalloped by erosion, and it appears that the material has flowed along the canyon floor.
Portions of two more mountains can be seen on the right side of the image. The depression between these mountains is Shamshu Patera, a volcanic hotspot. The dark patches within it are recent and active lava flows. The northernmost edge of Shamshu Patera appears to be cutting into the mountain to its northeast.
North is to the top of the picture and the Sun illuminates the surface from the west. This mosaic has a resolution of about 345 meters (1,130 feet) per picture element and covers an area approximately 390 by 380 kilometers (240 by 235 miles) at its maximum dimensions. It is centered at about 9 degrees south latitude and 68 degrees west longitude. The images that make up this mosaic were acquired at a range of 34,500 kilometers (21,400 miles) by Galileo's onboard camera.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Below them are the corresponding views of Io in reflected sunlight, reprojected from a global mosaic of images obtained during Galileo's first and second orbits of Jupiter. These lit views help to identify the locations of the hot spots seen in the eclipse images. The grid marks are at 15 degree intervals of latitude and longitude. North is to the top.
In the eclipse images (top) small red ovals and perhaps some small green areas are due to thermal emission from volcanic hot spots with temperatures hotter than about 700 kelvin (about 1000 degrees Fahrenheit). Diffuse greenish areas seen near the limb or edge of the moon are probably the result of auroral and/or airglow emissions of neutral species of oxygen or sulfur in volcanic plumes and in Io's patchy atmosphere.
All images were acquired by the solid state imaging (CCD) system on NASA's Galileo spacecraft. The top left image was obtained during the spacecraft's fourth orbit (E4) on December 17, 1996, the top middle image during the sixth orbit (E6) on February 21, 1997, and the top right image during the first orbit (G1) on June 29th, 1996. The relatively long exposures used to obtain these eclipse images lead to some smearing of the picture elements which reduces the actual resolution. Unsmeared they would have resolutions of 17.6, 9.1, and 10.5 kilometers per picture element respectively (left to right).
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).
Concurrent results from Galileo's exploration of Io appear in the October 15th, 1997 issue of Geophysical Research Letters. The papers are: Temperature and Area Constraints of the South Volund Volcano on Io from the NIMS and SSI Instruments during the Galileo G1 Orbit, by A.G. Davies, A.S. McEwen, R. Lopes-Gautier, L. Keszthelyi, R.W. Carlson and W.D. Smythe. High-temperature hot spots on Io as seen by the Galileo Solid-State Imaging (SSI) experiment, by A. McEwen, D. Simonelli, D. Senske, K. Klassen, L. Keszthelyi, T. Johnson, P. Geissler, M. Carr, and M. Belton. Io: Galileo evidence for major variations in regolith properties, by D. Simonelli, J. Veverka, and A. McEwen.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA00739: Eclipse Images of Io (3 views) sur le site de la NASA.
This dramatic image of Io was taken by the Long Range Reconnaissance Imager (LORRI) on New Horizons at 11:04 Universal Time on February 28, 2007, just about 5 hours after the spacecraft's closest approach to Jupiter. The distance to Io was 2.5 million kilometers (1.5 million miles) and the image is centered at 85 degrees west longitude. At this distance, one LORRI pixel subtends 12 kilometers (7.4 miles) on Io.
This processed image provides the best view yet of the enormous 290-kilometer (180-mile) high plume from the volcano Tvashtar, in the 11 o'clock direction near Io's north pole. The plume was first seen by the Hubble Space Telescope two weeks ago and then by New Horizons on February 26; this image is clearer than the February 26 image because Io was closer to the spacecraft, the plume was more backlit by the Sun, and a longer exposure time (75 milliseconds versus 20 milliseconds) was used. Io's dayside was deliberately overexposed in this picture to image the faint plumes, and the long exposure also provided an excellent view of Io's night side, illuminated by Jupiter. The remarkable filamentary structure in the Tvashtar plume is similar to details glimpsed faintly in 1979 Voyager images of a similar plume produced by Io's volcano Pele. However, no previous image by any spacecraft has shown these mysterious structures so clearly.
The image also shows the much smaller symmetrical fountain of the plume, about 60 kilometers (or 40 miles) high, from the Prometheus volcano in the 9 o'clock direction. The top of a third volcanic plume, from the volcano Masubi, erupts high enough to catch the setting Sun on the night side near the bottom of the image, appearing as an irregular bright patch against Io's Jupiter-lit surface. Several Everest-sized mountains are highlighted by the setting Sun along the terminator, the line between day and night.
This is the last of a handful of LORRI images that New Horizons is sending "home" during its busy close encounter with Jupiter -- hundreds of images and other data are being taken and stored onboard. The rest of the images will be returned to Earth over the coming weeks and months as the spacecraft speeds along to Pluto.
This stereo image illustrates the topography of the Tvashtar Catena region on Jupiter's moon Io. It was created by combining two different views of Tvashtar taken by NASA's Galileo spacecraft on November 25,1999 (shown in red) and February 22, 2000 (shown in blue).
A raised plateau surrounds the volcanic depression, or caldera, in the center of the image. To the northeast of the main caldera, the plateau's inner and outer margins are scalloped, which may indicate that a process called sapping is eroding them. Sapping occurs when fluid escapes from the base of a cliff, causing the material above it to collapse. Smaller calderas have formed in the floor of the main caldera. This nesting of calderas is also observed on Earth, at Kilauea in Hawaii. (The two bright red regions toward the upper left of this image, which are roughly triangular in shape, are the areas where the earlier image was overexposed by the brightness of hot lava fountains).
Galileo scientists are in the process of generating topographic maps from these images. Such maps will reveal the heights and slopes of different landforms in this region, which will help scientists determine the strength and other properties, of Io's surface materials. They will also be useful in understanding the processes of uplift and erosion on Io.
The picture is centered at 59 degrees north latitude and 121 degrees west longitude. North is to the top of the picture and the Sun illuminates the surface from the lower left. The observations used to make the stereo image were made at ranges of 18,000 and 34,500 kilometers (11,400 and 21,600 miles) from Io. The resolution of the stereo image is about 320 meters (350 yards) per picture element.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
This image taken by NASA's Galileo spacecraft on Oct. 16, 2001, near the equator of Jupiter's moon Io shows the contrast in volcanism styles found on Io.
The central feature is a large patera, or volcanic depression, almost 100 kilometers (60 miles) long. It may have formed after eruptions of lava emptied a subsurface magma chamber and left an empty space into which the crust collapsed. Evidence of lava flows associated with this patera, however, is difficult to find. Either the flows have been buried, or perhaps they never erupted and simply drained back deep into the crust.
On the right of the image is a small shield volcano, similar to volcanoes in Hawaii. It is rare for lavas on Io to be thick enough to pile up into shields around vents. They usually run out in thin, long flows instead. This shield abuts some very pale lava flows that emerged from a small vent to the west. These flows could be made of sulfur, like flows at Io's Emakong Patera. The vent is also surrounded by dark, diffuse material, which may be the result of lava erupted in an explosive, gas-rich eruption, similar to the 1980 eruption of Mount Saint Helens in Washington.
North is to the top of the image and the illumination is from the right. The image has a resolution of 330 meters (1,080 feet) per picture element and is 340 (211 miles) kilometers across.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA03532: Volcanic Depression and Shield Volcano, Io sur le site de la NASA.
This picture is a composite of a black and white near infrared image of Jupiter and its satellite Io and a color image of Io at shorter wavelengths taken at almost the same time on March 5, 1994. These are the first images of a giant planet or its satellites taken by NASA's Hubble Space Telescope (HST) since the repair mission in December 1993.
Io is too small for ground-based telescopes to see the surface details. The moon's angular diameter of one arc second is at the resolution limit of ground based telescopes.
Many of these markings correspond to volcanoes that were first revealed in 1979 during the Voyager spacecraft flyby of Jupiter. Several of the volcanoes periodically are active because Io is heated by tides raised by Jupiter's powerful gravity.
The volcano Pele appears as a dark spot surrounded by an irregular orange oval in the lower part of the image. The orange material has been ejected from the volcano and spread over a huge area. Though the volcano was first discovered by Voyager, the distinctive orange color of the volcanic deposits is a new discovery in these HST images. (Voyager missed it because its cameras were not sensitive to the near-infrared wavelengths where the color is apparent). The sulfur and sulfur dioxide that probably dominate Io's surface composition cannot produce this orange color, so the Pele volcano must be generating material with a more unusual composition, possibly rich in sodium.
The Jupiter image, taken in near-infrared light, was obtained with HST's Wide Field and Planetary Camera in wide field mode. High altitude ammonia crystal clouds are bright in this image because they reflect infrared light before it is absorbed by methane in Jupiter's atmosphere. The most prominent feature is the Great Red Spot, which is conspicuous because of its high clouds. A cap of high-altitude haze appears at Jupiter's south pole.
The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Space Flight Center for NASA's Office of Space Science.
This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/.
Voir l'image PIA01267: Hubble Space Telescope Resolves Volcanoes on Io sur le site de la NASA.
This image taken by NASA's Galileo spacecraft during its close flyby of Jupiter's moon Io on November 25, 1999 shows some of the curious mountains found there. The Sun is illuminating the scene from the left, and because it is setting, the Sun exaggerates the shadows cast by the mountains. By measuring the lengths of these shadows, Galileo scientists can estimate the height of the mountains. The mountain just left of the middle of the picture is 4 kilometers (13,000 feet) high and the small peak to the lower left is 1.6 kilometers (5,000 feet) high.
These mountains, like others imaged during a previous Galileo flyby of Io in October, seem to be in the process of collapsing. Huge landslides have left piles of debris at the bases of the mountains. The ridges that parallel their margins are also indicative of material moving down the mountainsides due to gravity.
North is to the upper left of the picture. The image, centered at -8.1degrees latitude and 78.7 degrees longitude, covers an area approximately 210-by-110 kilometers (130-by-70 miles). The resolution is 267 meters (880 feet) per picture element. The image was taken at a range of 25,000 kilometers (16,000 miles) by Galileo's onboard camera.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
The Zal Patera region of Jupiter's volcanic moon Io is shown in this combination of high-resolution black and white images taken by NASA's Galileo spacecraft on November 25, 1999 and lower resolution color images taken by Galileo on July 3, 1999. By combining both types of images, Galileo scientists can better understand the relationships between the different surface materials and the underlying geologic structures. For example, in the center toward the top of the picture, the edge of the caldera, or volcanic crater, is marked by the black flows, and it coincides with the edge of a plateau. Also, the red material (just above and to the right of the center of the image) is typically associated with regions where lava is erupting onto the surface. Here the red material follows the base of a mountain, which may indicate that sulfurous gases are escaping along a fault associated with the formation of the mountain.
Scientists can use the lengths of the shadows cast to estimate the height of the mountains. They estimate that the northernmost plateau, which bounds the western edge of Zal Patera, rises up to approximately 2 kilometers (6,600 feet) high. The mountain to the south of the caldera has peaks up to approximately 4.6 kilometers (15,000 feet) high, while the small peak at the bottom of the picture is approximately 4.2 kilometers (14,000 feet) high.
North is to the top of the image, which is centered at 33.7 degrees north latitude and 81.9 degrees west longitude. The higher resolution images have a sharpness of about 260 meters (or yards) per picture element, and they are illuminated from the left. These images were taken on November 25, 1999 at a range of 26,000 kilometers (16,000 miles). The color images are illuminated from almost directly behind the Galileo spacecraft. The resolution of the color images is 1.3 kilometers (0.8 miles) per picture element. They were taken on July 3, 1999 at a distance of about 130,000 kilometers (81,000 miles).
The Jet Propulsion Laboratory, Pasadena, CA manages Galileo for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA02527: Zal Patera, Io, in color sur le site de la NASA.
NASA's Galileo spacecraft acquired its highest resolution images of Jupiter's moon Io on 3 July 1999 during its closest pass to Io since orbit insertion in late 1995. This color mosaic uses the near-infrared, green and violet filters (slightly more than the visible range) of the spacecraft's camera which have been processed to enhance more subtle color variations. Most of Io's surface has pastel colors, punctuated by black, brown, green, orange, and red units near the active volcanic centers. A true color version of the mosaic has been created to show how Io would appear to the human eye.
The improved resolution reveals small-scale color units which had not been recognized previously and which suggest that the lavas and sulfurous deposits are composed of complex mixtures (Cutout locations), (Cutout A). Some of the bright (whitish), high-latitude (near the top and bottom) deposits have an ethereal quality like a transparent covering of frost (Cutout B). Bright red areas were seen previously only as diffuse deposits. However, they are now seen to exist as both diffuse deposits and sharp linear features like fissures (Cutout C). Some volcanic centers have bright and colorful flows, perhaps due to flows of sulfur rather than silicate lava (Cutout D). In this region bright, white material can also be seen to emanate from linear rifts and cliffs.
Comparison of this mosaic to http://www.jpl.nasa.gov/galileo/sepo./atjup/io/color.html">previous Galileo images reveals many changes due to the ongoing volcanic activity.
Galileo will make two close passes of Io beginning in October of this year. Most of the high-resolution targets for these flybys are seen on the hemisphere shown here.
North is to the top of the picture and the sun illuminates the surface from almost directly behind the spacecraft. This illumination geometry is good for imaging color variations, but poor for imaging topographic shading. However, some topographic shading can be seen here due to the combination of relatively high resolution (1.3 kilometers or 0.8 miles per picture element) and the rugged topography over parts of Io. The image is centered at 0.3 degrees north latitude and 137.5 degrees west longitude. The resolution is 1.3 kilometers (0.8 miles) per picture element. The images were taken on 3 July 1999 at a range of about 130,000 kilometers (81,000 miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft during its twenty-first orbit.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo
Voir l'image PIA02309: Global image of Io (false color) sur le site de la NASA.
Hot eruption sites scattered across Jupiter's moon Io stand out dramatically in an infrared image taken Oct. 13, 2001, by NASA's Galileo spacecraft as it sped past this most volcanically active of all known worlds.
The infrared image (right) serves as a thermal map to nearly a full hemisphere of Io. An image from Galileo's camera showing the same face of Io (left) is included for correlating the heat-sensing infrared data with geological features apparent in visible wavelengths. When Galileo snapped the infrared shot, the left half of the hemisphere was actually in darkness and the right half in daylight.
The infrared image uses false color to portray the intensity with which the surface glows at the invisible wavelength of 5 microns, as observed by Galileo's near infrared mapping spectrometer instrument. White, reds and yellows indicate hotter regions; blues are cold. The resolution varies from 83 to 93 kilometers (52 to 58 miles) per picture element.
Four previously unknown volcanoes have been discovered from this image, including one also detected in another infrared image taken the same day. Those new-found hot spots are faint. Among the more easily identified brighter volcanoes in the image are the pair Pillan and Pele located near the left-hand edge at about 8 o'clock if the circular image is taken as a clock face. Marduk is located a little farther from the edge at 7 o'clock. The bright spot at about 2 o'clock is the site where a plume was seen erupting about 500 kilometers (320 miles) high 10 weeks before this image was taken.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/.
Voir l'image PIA03535: Io in Infrared, Night and Day sur le site de la NASA.
This NASA Hubble Space Telescope pair of images of Jupiter's volcanic moon Io shows the surprising emergence of a 200-mile diameter large yellowish-white feature near the center of the moon's disk (photo on the right). This is a more dramatic change in 16 months than any seen over the previous 15 years, say researchers. They suggest the spot may be a new class of transient feature on the moon. For comparison the photo on the left was taken in March 1994 -- before the spot emerged - - and shows that Io's surface had undergone only subtle changes since it was last seen close-up by the Voyager 2 probe in 1979. The new spot seen in the July 1995 Hubble image replaces a smaller whitish spot seen in about the same place in the March 1994 image. Note the much more subtle changes seen elsewhere on this face of Io over the 16 months between the images. Each image is a composite of frames taken at near-ultraviolet, violet, and yellow wavelengths, with Hubble's Wide Field and Planetary Camera 2. "The new spot surrounds the volcano Ra Patera, which was photographed by Voyager, and is probably composed of material, probably frozen gas, ejected from Ra Patera by a large volcanic explosion or fresh lava flows...," according to John Spencer of Lowell Observatory in Flagstaff, Arizona. The new bright spot is also unusual because it is much yellower than other bright regions of Io, which are whitish in color. The unusual color may result from the freshness of the deposit and will probably provide clues as to the composition of new volcanic materials on Io. The temperature on Io's surface is about -150 degrees Celsius (-238 degrees Fahrenheit); however, "hot spots" associated with volcanic activity may be as warm as 1,000 degrees Celsius (1,800 degrees Fahrenheit). Follow-up observations by Hubble, in coordination with the Galileo spacecraft, scheduled to arrive at Jupiter and fly by Io in December 1995, will reveal the evolution and lifetime of the new feature. Galileo will be able to see much greater detail on Io in visible light, but will still rely on information gleaned from Hubble UV observations and Hubble observations taken at times when Galileo cannot observe Io. These further observations should also tell whether astronomers have witnessed, for the first time, one of the processes which creates the bright regions on Io.
This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL http://oposite.stsci.edu/.
Voir l'image PIA01260: Hubble Discovers Bright New Spot on Io sur le site de la NASA.
This collage of images shows the dizzying rate of geologic activity at one of the many erupting volcanoes on Jupiter's moon Io, as viewed by NASA's Galileo spacecraft during the closest-ever Io flyby on October 10, 1999. The top panel shows the best overall view of the Prometheus volcano, combining a picture at a resolution of 120 meters (400 feet) per picture element with a picture at a resolution of 1.5 kilometers (about one mile) per picture element. Inset within this panel is a smaller copy of the mosaic with a temperature map superimposed.
The Galileo camera took the pictures, while the temperatures were measured by the spacecraft's near infrared mapping spectrometer instrument. Combining these data, Galileo scientists have created a description of the eruption at Prometheus. The magma is stored in an underground chamber beneath the caldera (dark, bean-shaped feature) at the northeastern end of Prometheus (top right). The lava reaches the surface about 15 kilometers(10 miles) south of the caldera. This point is marked by the blue, eastern hot spot in the temperature map and by a streak of red, sulfur-rich material (see color panel on the lower left). From the volcanic vent, the lava travels almost 100 kilometers (60 miles) through lava tubes to the front of the flow. The exposed liquid lava produces the large high temperature area on the western end of Prometheus (color panel at lower left). A 100 kilometer(60 mile) tall plume of sulfur-dioxide rich gas also rises above these active lava flows. A smaller breakout of liquid lava midway along the tube forms a faint (purple) hot spot.
Scientists at the University of Arizona, compared the pictures taken on July 3rd and October 10th of this year. They found that changes (see middle and right lower panels) have occurred in the intervening 3 months. A breakout from the middle of the lava tube appears to have taken place within this three-month period, spreading a new dark deposit to the north of the older lava flows. It also appears that the gas discharge from the volcanic vent at the eastern end of the flow has increased. There is a new fan of dark material streaming out from this location. Furthermore, the new, bright crescent-shaped deposit across the middle of Prometheus suggests that the main (western) plume has been pushed aside by the increased gas release to the east.
North is to the top in all images and the sun is illuminating the surface from slightly to the left of overhead. All the images are centered at 2 degrees south and 154 degrees west. The top image has a resolution of 1.5 kilometers (about one mile) per picture element and the high-resolution inset has a resolution of 120 meters (390 feet). The color image at the bottom has a resolution of 2.6 kilometers (1.6 miles) per picture element. The two black and white image at the bottom have resolutions of 1.5 kilometers (about one mile) per picture element.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
The mosaic at left combines higher-resolution images (330 meters or about 1080 feet per picture element) taken in October 2001 with lower-resolution color images (1.4 kilometers or 0.9 mile per picture element) taken in July 1999 by Galileo's solid-state imaging camera.
By comparing these images with a map of hot spots taken in February by Galileo's near-infrared mapping spectrometer (lower right), Galileo scientists noted that a new hot spot west of the active volcano Prometheus became bright in February 2000 and dimmed later. This hot spot appears to correspond with the bright flow field just west of a recently discovered shield volcano (see PIA03532), which is the only fresh volcanic material in the area.
The relatively low intensity of the February 2000 hot spot in the infrared data suggests a low-temperature eruption, consistent with sulfur lava rather than silicate lava as found elsewhere on Io and also on Earth. Sulfur lavas are thought to cool to a gray-yellow color on Io, as seen in the new flow field visible in the camera image. This bright flow field could be the best example of active sulfur lava flows deposited on Io during the Galileo mission. At upper right is a global view of Io showing the location of the more-detailed images.
The low temperature of this hot spot differs from many of Io's other active volcanoes, such as Pele, Tvashtar and Prometheus. Intense tidal flexing of Io helps keep the moon's interior molten, at some places producing silicate lavas hotter than any seen on Earth in billions of years. Io has the greatest known diversity of volcanic activity in the solar system.
North is to the top of all these images.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA03887: Potential Source of Sulfur Flow on Io sur le site de la NASA.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01066: Changes around Marduk between Voyager, and Galileo's first two orbits sur le site de la NASA.
North is to the top of the picture and the sun illuminates the surface from the left. The image covers an area 2000 kilometers wide and the smallest features that can be discerned are 2.5 kilometers in size. This image was taken on November 6th, 1996, at a range of 245,719 kilometers by the Solid State Imaging (CCD) system on the Galileo Spacecraft.
Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA00536: Geologic Landforms on Io sur le site de la NASA.
Click on the image for QuickTime movie of
Tvashtar Movie
Using its Long Range Reconnaissance Imager (LORRI), the New Horizons spacecraft captured the two frames in this "movie" of the 330-kilometer (200-mile) high Tvashtar volcanic eruption plume on Jupiter's moon Io on February 28, 2007, from a range of 2.7 million kilometers (1.7 million miles). The two images were taken 50 minutes apart, at 03:50 and 04:40 Universal Time, and because particles in the plume take an estimated 30 minutes to fall back to the surface after being ejected by the central volcano, each image likely shows an entirely different set of particles. The details of the plume structure look quite different in each frame, though the overall brightness and size of the plume remain constant.
Surface details on the nightside of Io, faintly illuminated by Jupiter, show the 5-degree change in Io's central longitude, from 22 to 27 degrees west, between the two frames.This mosaic combines images collected in February 2000 and the summer of 1999 by NASA's Galileo spacecraft to highlight new details of the longest active lava flow known in the solar system.
The area, called Amirani, has been known to be the home of a number of volcanic hot spots ever since NASA's two Voyager spacecraft flew by Jupiter in 1979. Images collected by Galileo in 1999 showed that these hot areas were part of a single immense lava flow field. The newest images confirm that the Amirani flow field is indeed a quilt work of dark lava flows. The most recent lavas are darkest because they are too hot to be covered by sulfur-dioxide plumes. Fresh lava is leaking out of at least five areas at the northern end of the Amirani flow field and at least three places in the middle. However, it is likely that the lava first comes to the surface near the southern end of the flow field. The liquid lava travels under a frozen layer of older lava, breaking out onto the surface only after traveling hundreds of kilometers (hundreds of miles) from the vent. The "small" breakouts produce lava flows larger than the current eruption on Earth at Kilauea Volcano in Hawaii. These observations are helping to explain how very large, ancient lava flows formed on the Earth.
While the behavior of the lava once it is on the surface makes sense, how it comes to the surface is more complicated. Small, white, diffuse halos surrounding the darkest lava flows are probably sulfur-dioxide-rich snows and frosts that have been vaporized by the hot lava. The bright red material to the south of the Amirani flow field is likely to contain a large fraction of sulfur droplets. Sulfur-rich gas appears to be bubbling out all along the east-west crack at the southern end of Amirani. This may be the crack along which the lava rises to the surface. The main Amirani plume appears to emanate from a fuzzy, purplish area within the southern part of the flow field. This is a plausible alternative location for the lava to come to the surface.
The mosaic shows an area 500 kilometers (310 miles) long and 180 kilometers (110 miles) wide. Black and white images at 210 meters (690 feet) per picture element were combined with color data at 1.3 kilometers (.8 miles) per picture element. This computer wizardry allows us to learn much more than either set of pictures alone. North is to the top of the picture.
The Jet Propulsion Laboratory, Pasadena, Calif., manages the mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
North is to the top of the picture which combines images acquired using violet, green, and near-infrared (756 micrometers) filters. The resolution is 21 kilometers per picture element. The images were taken on June 27, 1997 at a range of 1,033,000 kilometers by the solid state imaging (CCD) system on NASA's Galileo spacecraft.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01220: Io's Kanehekili Hemisphere sur le site de la NASA.
Variations in the appearance of the giant plume from the Tvashtar volcano on Jupiter's moon Io are seen in this composite of the best photos taken by the New Horizons Long Range Reconnaissance Imager (LORRI) during its Jupiter flyby in late February-early March 2007.
New Horizons was fortunate to witness this unusually large plume during its brief Jupiter flyby; the Galileo Jupiter orbiter spent more than five years imaging the volcanic moon (between 1996 and 2001) without ever capturing such detailed pictures of a large Io plume. The plume is roughly 330 kilometers (200 miles) high. The cause of the fine wispy structure in the plume, which varies strikingly from image to image, is unknown, but these pictures may help scientists to understand the phenomenon.The pictures were taken at distances ranging from 3.1 to 2.3 million kilometers (1.9 to 1.4 million miles), but they have been scaled to show the plume at the same relative size in every frame. Illumination conditions also vary: in the final image, Io's shadow cuts across the plume and hides all but its topmost regions, and the glow of hot lava can be seen on the nightside at the source of the plume. The times of the images, from top to bottom, are: February 26, 18:38 (Universal Time); February 26, 21:01; February 28, 03:50; February 28, 04:40; February 28, 11:04; and March 1, 00:35.The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01068: Changes east of Pele between Galileo's first two orbits sur le site de la NASA.
This global mosaic shows the highest resolution Galileo images available of Jupiter's moon, Io. North is to the top of the picture. The images, obtained at low sun illumination angles (high sun-target-spacecraft angles)which emphasize topographic shadows, were taken by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft over the course of several orbits. The grid identifies the names and locations of several of Io's main features. Several active but as yet unnamed volcanic features are indicated by arrows. While volcanic centers are rather evenly distributed, almost all of the active plumes and long-lived hot spots seen over the span of NASA's Galileo mission at Jupiter or during the flyby's of NASA's Voyager spacecraft in 1979 are within 30 degrees of the equator.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URLhttp://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.
Voir l'image PIA01663: Highest Resolution mosaic of Io sur le site de la NASA.
A: A global map of Jupiter's moon Io derived from eight images taken by the Long Range Reconnaissance Imager (LORRI) on the New Horizons spacecraft, as it passed Jupiter on its way to Pluto in late February 2007. Details as small as 12 kilometers (7 miles) are visible. The map shows the comprehensive picture of Io's volcanism obtained by New Horizons. Yellow ovals denote areas with new, faded or shifted plume deposits since the last images taken by the Galileo spacecraft in 2001. Green circles denote areas where probable new lava flows have occurred. Cyan diamonds indicate locations of active volcanic plumes, and orange hexagons are volcanic hot spots detected by the Linear Etalon Imaging Spectral Array (LEISA) instrument. For plumes and hot spots, symbol size indicates the approximate relative size and brightness of the features.
B-F: Comparison of New Horizons (NH) and earlier images of major surface changes discovered by New Horizons at Io's volcanoes Masubi (45 degrees S, 57 degrees West) and North Lerna (55 degrees S, 290 degrees W). The scale bars are 200 kilometers long, and a is the solar phase angle. At Masubi, old lava flows seen by Voyager and Galileo (B) have been obscured at low phase angles (C) by deposits from two active plumes associated with a new 240-kilometer (150-mile) long dark lava flow, which is the longest lava flow known to have been erupted in the solar system since the discovery of Io volcanism in 1979. At North Lerna, a recent eruption has generated a 130-km long lava flow (F), as well as an active plume that has produced a concentric pattern of deposits.
NASA's Galileo spacecraft observed this volcano, Emakong Patera, a large, dark caldera from which numerous bright flows extend out in all directions, on November 25, 1999. Unlike many of the other volcanoes on Io, high-temperature material has never been observed at Emakong. These high-resolution (150 meters, or 164 yards, per picture element) images revealing the intricate nature of the lava flows were taken during Galileo's 25th orbit.
A bright flow emanates to the southeast of the caldera and spreads eastward. A dark channel runs through the flow and may have fed it as it grew. The margins of this bright flow are convoluted, indicating that the lava was able to move through narrow topographic constrictions, or that inexperienced numerous small breakouts. These observations are consistent with a low-viscosity liquid. A contender for the composition of this bright, low-viscosity lava is sulfur. While Galileo has frequently detected high-temperature silicate lava flows, sulfur flows may also be a major component of the surface. Fresh bright flows cover about two-percent of the surface, similar to the coverage by dark flows.
The images were taken at a distance of 15,000 kilometers (9,400 miles) from Io. North is 13 degrees to the left of up. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
NASA's Galileo spacecraft caught this volcanic eruption in action on Jupiter's moon Io on November 25, 1999. This mosaic shows Tvashtar Catena, a chain of calderas, in enhanced color. It combines low resolution (1.3 kilometers, or .8 miles, per picture element) color images of Io taken on July 3, 1999 with the much higher resolution (180 meters, or 197 yards, per picture element) black and white images taken in November. The molten lava was hot enough, and therefore bright enough, to saturate, or overexpose, Galileo's camera (original image is inset in lower right corner). The bright lava curtain (a chain of lava fountains) and surface flows shown in the color image were assembled as an interpretive drawing by Galileo scientists, based on their knowledge of how the camera behaves when saturated. The lava appears to be producing fountains to heights of up to 1.5 kilometers (5,000 feet) above the surface. Several other lava flows can be seen on the floors of the calderas. The darkest flows are probably the most recent.
The elongated caldera in the center of the image is almost surrounded by a mesa that is about 1 kilometer (.6 miles) high. In places the mesas margins are scalloped, which is typical of an erosional process called sapping. This occurs when fluid escapes from the base of a cliff, causing the material above it to collapse. On Earth, sapping is caused by springs of groundwater. Similar features on Mars are one of the key pieces of evidence that water flowed on Mars surface in the past. On Io, the fluid is believed to be sulfur dioxide, which should vaporize almost instantaneously when it reaches the near vacuum at Io's surface, blasting away material at the base of the cliffs.
North is to the top of the image and the Sun illuminates the surface from the lower left. The high resolution black and white image was taken at a distance of 17,000 kilometers (11,000 miles).
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
A diffuse ring of bright red material encircles Pele, the site of an ongoing, high velocity volcanic eruption. Pele's plume is nearly invisible, except in back-lit photographs, but its deposits indicate energetic ejection of sulfurous materials out to distances more than 600 kilometers from the central vent. Another bright red deposit lies adjacent to Marduk, also a currently active ediface. High temperature hot spots have been detected at both these locations, due to the eruption of molten material in lava flows or lava lakes. Bright red deposits on Io darken and disappear within years or decades of deposition, so the presence of bright red materials marks the sites of recent volcanism.
This composite was created from data obtained by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft. The region imaged is centered on 15 degrees South, 224 degrees West, and is almost 2400 kilometers across. The finest details that can be discerned in this picture are about 3 kilometers across. North is towards the top of the picture and the sun illuminates the surface from the west.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01112: Pele Plume Deposit on Io sur le site de la NASA.
Io, the most volcanic body in the solar system, is seen in front of Jupiter's cloudy atmosphere in this image from NASA's Galileo spacecraft, now orbiting the giant planet. This newly processed image is the best and highest resolution view of Io produced thus far by Galileo. Galileo was about 487,000 kilometers (about 302,000 miles) from Io when this was taken on September 7, 1996, and Jupiter was about 908,000 kilometers (about 564,000 miles) away. The image is centered on the side of Io that always faces away from Jupiter. The color in the image is composed of data taken in the near-infrared, green and violet filters of Galileo's solid-state imaging camera, and has been enhanced to emphasize the extraordinary variations in color and brightness that characterize Io's volcano-pocked face. The black and bright red materials correspond to the most recent volcanic deposits, probably no more than a few years old. The near-infrared filter makes Jupiter's atmosphere look blue. The active volcano Prometheus is seen near the right-center of the disk. Scientists are noting many changes that have occurred on Io's surface since the Voyager flybys 17 years ago, and even a few changes in the two months since Galileo's imaging of Io this summer.
The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http:// www.jpl.nasa.gov/galileo/sepo
Voir l'image PIA00494: Io in front of Jupiter sur le site de la NASA.
This beautiful image of the crescents of volcanic Io and more sedate Europa was snapped by New Horizons' color Multispectral Visual Imaging Camera (MVIC) at 10:34 UT on March 2, 2007, about two days after New Horizons made its closest approach to Jupiter.
The picture was one of a handful of the Jupiter system that New Horizons took primarily for their artistic, rather than scientific value. This particular scene was suggested by space enthusiast Richard Hendricks of Austin, Texas, in response to an Internet request by New Horizons scientists for evocative, artistic imaging opportunities at Jupiter.
This image was taken from a range of 4.6 million kilometers (2.8 million miles) from Io and 3.8 million kilometers (2.4 million miles) from Europa. Although the moons appear close in this view, a gulf of 790,000 kilometers (490,000 miles) separates them. The night side of Io is illuminated here by light reflected from Jupiter, which is out of the frame to the right. Europa's night side is completely dark, in contrast to Io, because that side of Europa faces away from Jupiter.
Here, Io steals the show with its beautiful display of volcanic activity. Three volcanic plumes are visible. Most conspicuous is the enormous 300-kilometer (190-mile) -high plume from the Tvashtar volcano at the 11 o'clock position on Io's disk. Two much smaller plumes are barely visible: one from the volcano Prometheus, at the 9 o'clock position on the edge of Io's disk, and one from the volcano Amirani, seen between Prometheus and Tvashtar along Io's terminator (the line dividing day and night). The plumes appear blue because of the scattering of light by tiny dust particles ejected by the volcanoes, similar to the blue appearance of smoke. In addition, the contrasting red glow of hot lava can be seen at the source of the Tvashtar plume.
The images are centered at 1 degree north, 60 degrees west on Io, and 0 degrees north, 149 degrees west on Europa. The color in this image was generated using individual MVIC images at wavelengths of 480, 620 and 850 nanometers. The human eye is sensitive to slightly shorter wavelengths, from 400 to 700 nanometers, and thus would see the scene slightly differently. For instance, while the eye would notice the difference between the yellow and reddish brown colors of Io's surface and the paler color of Europa, the two worlds appear very similar in color to MVIC's longer-wavelength vision. The night side of Io appears greenish compared to the day side, because methane in Jupiter's atmosphere absorbs 850-nanometer light and makes Jupiter-light green to MVIC's "eyes."
MVIC is a component of the Ralph imaging instrument.
NASA's Galileo spacecraft acquired its highest resolution images of Jupiter's volcanic moon Io on July 3, 1999 during its closest pass by Io since it entered orbit around Jupiter in December 1995. This color mosaic uses the near-infrared, green and violet filters (slightly more than the visible range) of the spacecraft's camera, processed to enhance more subtle color variations. Most of Io's surface has pastel colors, punctuated by black, brown, green, orange, and red areas near the active volcanic centers.
The improved resolution reveals small-scale color areas which were not recognized previously and which suggest that the lava and sulfurous deposits are composed of complex mixtures (close-up A). Some of the bright, whitish, high-latitude (near the top and bottom) deposits have an ethereal quality like a transparent covering of frost (close-up B). Bright red areas were seen in previous images only as diffuse deposits. However, they now appear as both diffuse deposits and sharp linear features like fissures (close-up C). Some volcanic centers have bright and colorful flows, perhaps due to flows of sulfur (rather than silicate) lava (close-up D). In this region of Io, bright, white material can also be seen to emanate from linear rifts and cliffs.
Comparison of this mosaic to http://www.jpl.nasa.gov/galileo/sepo./atjup/io/color.html">previous Galileo images reveals many changes due to ongoing volcanic activity.
Galileo is scheduled to make two close passes of Io in October and November. Most of the high-resolution targets for these flybys are seen on the hemisphere shown here.
North is to the top of the picture, and the Sun illuminates the surface from almost directly behind the spacecraft. This illumination is good for imaging color variations, but poor for imaging topographic shading. However, some topographic shading can be seen here due to the combination of relatively high resolution (1.3 kilometers or 0.8 miles per picture element) and rugged topography over parts of Io. The mosaic is centered at 0.3 degrees north latitude and 137.5 degrees west longitude. The images were taken at a distance of about 130,000 kilometers (81,000 miles) by Galileo's onboard solid state imaging camera.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web at URL http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo
Voir l'image PIA02319: Closeups of Io (false color) sur le site de la NASA.
This mosaic of images shows a portion of a long lava flow that appeared during the 17 years between flybys of Io by NASA's Voyager and Galileo spacecraft. The images are high resolution (35-40 meters, or 38-44 yards per picture element), and were acquired by Galileo on October 11, 1999during its 24th orbit. The lava flow is 100 kilometers (60 miles) long.
The dark flows have intricate margins that are characteristic of a type of lava flow seen on Earth called pahoehoe. The source of the lava flows is a 25-kilometer (16-mile) long fissure that extends to the east of the central vent off the mosaic to the upper left. Some of the lava flows at the western end of the mosaic have channels with bright floors. These channels may have been carved by sulfur lava flows, or they may have been carved by silicate lava flows which were later covered by bright material.
North is to the top of the mosaic. The images were taken at a distance of 3,500 to 4,000 kilometers (2,200 to 2,500 miles) from Io. The large doses of radiation to which the spacecraft is subjected each time it passes close to Jupiter caused a problem with Galileo's camera, which resulted in scrambling of these images. Engineers at NASA's Jet Propulsion Laboratory, Pasadena, CA, were able to reconstruct the images, but black stripes remain where some data could not be recovered. The streaks from lower left to upper right are artifacts from the reconstruction.
JPL manages the mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
A plume of gas and particles is ejected some 100 kilometers (about 60 miles) above the surface of Jupiter's volcanic moon Io in this color image, recently taken by NASA¹s Galileo spacecraft.
The plume is erupting from near the location of a plume first observed by the Voyager spacecraft in 1979 and named Masubi. However, during the course of the Galileo tour of Jupiter and its moons, a plume has appeared at different locations within the Masubi region.
This color image is the same as the previously released false color mosaic of Io, but with special processing to enhance the visibility of the plume. The plume appears blue because of the way small particles in the plume scatter light.
North is to the top of the picture, and the Sun illuminates the surface from almost directly behind the spacecraft. The resolution is 1.3 kilometers (0.8 miles) per picture element. The images were taken on July 3, 1999 at a distance of about 130,000 kilometers (81,000 miles) by the Galileo¹s camera.
The two images on the left are actually the same image displayed indifferent ways. In the top-left image, the Masubi plume is too dim to be seen. The bottom-left image has been processed to enhance the visibility of the plume, which can be seen rising above the bottom-left edge of Io's disk. This processing overexposes the surface of Io so it appears completely white. In the pair of images on the right, a second image has been processed in similar fashion, so that Io's surface features are visible in the top-right image and are overexposed in the bottom-right image. This time Masubi is on the night side of Io, just beyond the terminator (the imaginary line separating day from night), but the plume is high enough that it extends up into the sunlight. A plume from the volcanoPrometheus can also be seen in this image, rising above the left edge of Io's disk. The diagonal line in the bottom-right image and the small bright spots sprinkled across all the images are caused by charged particles hitting the camera's CCD (charge-coupled device) detector.
North is to the top in all the images. The images on the left were taken by the on August 14, 1999 at a range of 1.1 million kilometers (700,000 miles) and have a resolution of 11 kilometers (7 miles) per picture element. The sun illuminates the surface from behind the spacecraft. The images on the right were taken on August 14, 1999 at a range of 1.6 million kilometers (1 million miles) and have a resolution of 16 kilometers (10 miles) per picture element. The sun illuminates the surface from the left.
Click on this image to viewThe Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.">http://www.jpl.nasa.gov/galileo/sepo.
The New Horizons Multicolor Visible Imaging Camera (MVIC) took this image of Jupiter's volcanic moon Io at 04:30 Universal Time on February 28, 2007, about one hour before New Horizons' closest approach to Jupiter, from a range of 2.7 million kilometers (1.7 million miles). Part of the Ralph imaging instrument, MVIC is designed for the very faint solar illumination at Pluto, and is too sensitive to image the brightly lit daysides of Jupiter's moons. Io's dayside is therefore completely overexposed in this image, and appears white and featureless. However, the Jupiter-lit nightside of Io and the giant plume from the Tvashtar volcano are well exposed, and the versions of the image shown here have been processed to bring out each of these features.
The scale of the original image is 53 kilometers (33 miles) per pixel; Io itself has a diameter of 3,630 kilometers (2,250 miles). The nightside of Io (left panel) is illuminated brightly enough by Jupiter to reveal many details in full color to MVIC's sensitive vision. The nightside color has been corrected to account for the greenish hue of Jupiter's light as seen by MVIC -- see the April 2 Featured Image of Io and Europa (PIA09256) -- so the colors approximate what the human eye would see in daylight illumination. The image shows Io's reddish-brown polar areas and the yellow and white colors of its equatorial regions, mostly due to various forms of sulfur. Several dark volcanic centers are also visible -- the most prominent, appearing as an elongated spot just above and to the right of the disk's center, is called Fjorgynn. Near the disk center, just over the night side of the terminator (the line separating day and night), is a row of three or four pale yellow patches, which likely are volcanic plumes catching the setting sun. These features have caught the attention of New Horizons scientists because no major plumes have been seen previously in this region of Io, and it is rare for Io's plumes to cluster so closely together.The right panel shows the bluish color of the plume from Tvashtar, rising above the overexposed edge of Io's disk at the 11 o'clock position. The plume is blue because it contains fine dust that preferentially scatters blue light, in the same way that smoke appears blue. The red line on the edge of the disk, below the plume, is an artifact caused by the overexposure of Io's surface.The image is centered at Io coordinates 26 degrees west, 6 degrees south, and is produced using MVIC's blue, red and near-infrared filters. In the original image, the overexposure of Io's dayside hemisphere caused extensive electronic "blooming" of the image toward the left and bottom edges of the frame, and this has been removed from the versions shown here.Dramatic shadows across a mountainous landscape on Jupiter's moon Io reveal details of the topography around a peak named Tohil Mons in this mosaic created from images taken by NASA's Galileo spacecraft in October 2001.
Tohil Mons rises 5.4 kilometers (18,000 feet) above Io's surface, according to analysis of stereo imaging from earlier Galileo flybys of Io. The new images, with a resolution of 327 meters (1,070 feet) per picture element, were taken when the Sun was low in the sky, producing informative shadows. North is to the top and the Sun illuminates the surface from the upper right. The topographic features revealed include a very straight ridge extending southwest from the peak, 500- to 850-meter-high (1,640- to 2,790-foot-high) cliffs to the northwest and a curious pit immediately east of the peak.
Major questions remain about how Io's mountains form and how they are related to Io's ubiquitous volcanoes. Although Io is extremely active volcanically, few of its mountains appear to be volcanoes. However, two volcanic craters do lie directly to the northeast of Tohil's peak, a smaller dark-floored one and a larger one at the very edge of the mosaic. Furthermore, the shape of the pit directly east of the peak suggests a volcanic origin. Galileo scientists will use these images to investigate the geologic history of Tohil Mons and its relationship to the neighboring volcanic features.
The image is centered at 28 degrees south latitude and 161 degrees west longitude.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA03600: Tall Mountain, Tohil Mons, on Io sur le site de la NASA.
Cutaway view of the possible internal structure of Io The surface of the satellite is a mosaic of images obtained in 1979 by NASA's Voyager spacecraft The interior characteristics are inferred from gravity field and magnetic field measurements by NASA's Galileo spacecraft. Io's radius is 1821 km, similar to the 1738 km radius of our Moon; Io has a metallic (iron, nickel) core (shown in gray) drawn to the correct relative size. The core is surrounded by a rock shell (shown in brown). Io's rock or silicate shell extends to the surface.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/galileo/sepo.
Voir l'image PIA01129: Interior of Io sur le site de la NASA.
The volcano called Prometheus, found on Jupiter's moon Io, could be called the Old Faithful of the outer solar system, because its volcanic plume has been visible every time it has been observed since 1979. This particular image, one of the highest-resolution pictures ever taken of Io, was obtained by NASA's Galileo spacecraft as it approached Io on July 3, 1999.
The volcanic plume of Prometheus has been visible during observations by Galileo (1996-1999) and NASA's Voyager spacecraft (1979). No other volcano on Io has been so stable in its behavior. However, between the Voyager flybys and the time of Galileo's arrival at Jupiter, the source of the plume has shifted about 70 kilometers (44 miles) to the west.
This false color close-up was taken of Prometheus using the near-infrared, green and violet filters (slightly greater than the visible range) of the spacecraft's camera and processed to enhance subtle color variations.
The long-lived plume has produced a ring-like deposit of bright white and yellow material that is likely to be rich in sulfur dioxide frost. Also note the denser jets in the plume that point like spokes to its source. Galileo scientists do not yet know whether this long-lived plume is erupting from a vent at the west end of the lava flow, or if the plume is being produced by the advancing lava as it flows over ground rich in sulfur dioxide.
Galileo will acquire black and white images of the Prometheus at resolutions between 35 to 70 meters (120 to 230 feet) per picture element and color images at resolutions of about 230 meters (750 feet) per picture element during its close flyby of Jupiter's moon Io on the evening of October 10, 1999 (Pacific time). These images will be important in understanding how volcanic plumes form on Io. In particular, we are interested in seeing if the plume material is escaping from Io's interior or from the surface at the front of active lava flows. These new images may help explain why Prometheus has been so faithfully active.
North is to the top of the picture, and the Sun illuminates the surface from almost directly behind the spacecraft. This illumination is good for imaging color variations, but poor for imaging topographic shading. However, some topography is visible here due to the combination of relatively high resolution (1.3 kilometers or 0.8 miles per picture element) and rugged areas over parts of Io. The image is centered at 2 degrees south latitude and 154 degrees west longitude. The images were taken at a distance of about 130,000 kilometers (81,000 miles) by Galileo's camera and have a resolution of 1.3 kilometers or 0.8 miles per picture element.
Click on this image to viewThe Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo
Voir l'image PIA02505: Close-up of Prometheus, Io (color) sur le site de la NASA.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01071: Changes on Io around Volund between Voyager 1 and Galileo's second orbit sur le site de la NASA.
This New Horizons image of Jupiter's volcanic moon Io was taken at 13:05 Universal Time during the spacecraft's Jupiter flyby on February 28, 2007. It shows the reddish color of the deposits from the giant volcanic eruption at the volcano Tvashtar, near the top of the sunlit crescent, as well as the bluish plume itself and the orange glow of the hot lava at its source. The relatively unprocessed image on the left provides the best view of the volcanic glow and the plume deposits, while the version on the right has been brightened to show the much fainter plume, and the Jupiter-lit night side of Io.
New Horizons' color imaging of Io's sunlit side was generally overexposed because the spacecraft's color camera, the super-sensitive Multispectral Visible Imaging Camera (MVIC), was designed for the much dimmer illumination at Pluto. However, two of MVIC's four color filters, the blue and "methane" filter (a special filter designed to map methane frost on the surface of Pluto at an infrared wavelength of 0.89 microns), are less sensitive than the others, and thus obtained some well-exposed views of the surface when illumination conditions were favorable. Because only two color filters are used, rather than the usual three, and because one filter uses infrared light, the color is only a rough approximation to what the human eye would see.
The red color of the Tvashtar plume fallout is typical of Io's largest volcanic plumes, including the previous eruption of Tvashtar seen by the Galileo and Cassini spacecraft in 2000, and the long-lived Pele plume on the opposite side of Io. The color likely results from the creation of reddish three-atom and four-atom sulfur molecules (S3 and S4) from plume gases rich in two-atom sulfur molecules (S2 After a few months or years, the S3 and S4 molecules recombine into the more stable and familiar yellowish form of sulfur consisting of eight-atom molecules (S8), so these red deposits are only seen around recently-active Io volcanos. Though the plume deposits are red, the plume itself is blue, because it is composed of very tiny particles that preferentially scatter blue light, like smoke. Also faintly visible in the left image is the pale-colored Prometheus plume, almost on the edge of the disk on the equator at the 9 o'clock position.
Io was 2.4 million kilometers from the spacecraft when the picture was taken, and the center of Io's disk is at 77 degrees West longitude, 5 degrees South latitude. The solar phase angle was 107 degrees.
Voir l'image PIA10249: Seeing Red sur le site de la NASA.
Six views of the volcanic plume named Prometheus, as seen against Io's disk and near the bright limb (edge) of the satellite by the SSI camera on the Galileo spacecraft during its second (G2) orbit of Jupiter. North is to the top of each frame. To the south-southeast of Prometheus is another bright spot that appears to be an active plume erupting from a feature named Culann Patera. Prometheus was active 17 years ago during both Voyager flybys, but no activity was detected by Voyager at Culann. Both of these plumes were seen to glow in the dark in an eclipse image acquired by the imaging camera during Galileo's first (G1) orbit, and hot spots at these locations were detected by Galileo's Near-Infrared Mapping Spectrometer.
The plumes are thought to be driven by heating sulfur dioxide in Io's subsurface into an expanding fluid or "geyser." The long-lived nature of these eruptions requires that a substantial supply of sulfur dioxide must be available in Io's subsurface, similar to groundwater. Sulfur dioxide gas condenses into small particles of "snow" in the expanding plume, and the small particles scatter light and appear bright at short wavelengths. The images shown here were acquired through the shortest-wavelength filter (violet) of the Galileo camera. Prometheus is about 300 km wide and 75 km high and Culann is about 150 km wide and less than 50 km high. The images were acquired on September 4, 1996 at a range of 2,000,000 km (20 km/pixel resolution). Prometheus is named after the Greek fire god and Culann is named after the Celtic smith god.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01069: Active Volcanic Eruptions on Io sur le site de la NASA.
Most of the 12 images in this mosaic were taken on February 22, 2000, by NASA's Galileo spacecraft. It has been merged with lower-resolution color data acquired by Galileo during the summer of 1999. The mosaic covers the region from Chaac Patera (the green-floored depression on the left side; see Cutout A (below)) to Camaxtli Patera (the depression with a dark halo in upper right; see Cutout B (below)). At least nine other paterae can be seen here.
This mosaic illustrates the range of patera morphology on Io. What is a patera? It is an irregular depression, or a complex one with scalloped edges, but which does not have the characteristics of an impact crater. The paterae on Io often correspond to active volcanic centers, and are in some ways similar to calderas. What's a caldera? Calderas are large, usually roughly circular depressions that form by collapse over shallow magma chambers that have been partially emptied by volcanic eruptions. However, the paterae on Io are different from calderas seen elsewhere in the solar system. They have many straight edges and sharp angles, suggesting that they are related to fractures in Io's crust. In many cases the lava can be seen to erupt from these straight edges. Planetary geologists aren't sure whether the paterae form over magma chambers or if they result from fractures and movements in the crust, and the lava subsequently follows the fractures.
One of the paterae (with orange and white materials--right center; see Cutout C (below)) shows what may be thin plates of crust that have broken off and rafted over a lava lake.
Also seen in this mosaic are various dark, bright, and reddish lava flows (towards the upper left but east of Chaac; see Cutout D (above)}) that are not confined to patera floors. The dark flows are associated with high temperatures consistent with silicate compositions. In fact, all the black areas in this mosaic correspond to high-temperature hot spots. The bright flows may have a different composition (such as sulfur) or they may be older silicate flows that have been coated by sulfurous materials.
The bright plains surrounding the volcanic centers have a bumpy texture. These plains are relatively old, so the roughness may develop slowly over time rather than representing the original topography of volcanic deposits. sublimation of sulfur dioxide is one process that might contribute to the texture.
The mosaic covers the region from latitude 7 north to 18 north, longitude 130 west to 160 west, with a total width of 850 kilometers (509 miles). The images have a resolution of 186 meters (200 yards) per picture element. The Sun is almost directly overhead (actually 12 degrees to the south), so most of the brightness variations in this image are due to different types of surface materials rather than topographic shading. Colors have been exaggerated.
The Jet Propulsion Laboratory, Pasadena, Calif., manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
This montage demonstrates New Horizons' ability to observe the same target in complementary ways using its diverse suite of instruments. Previously released views taken at visible and slightly longer infrared wavelengths with the Long Range Reconnaissance Imager (LORRI), New Horizons' high-resolution black-and-white camera, and the Multispectral Visible Imaging Camera (MVIC), its color camera, are here compared with a nearly simultaneous view from the Linear Etalon Imaging Spectral Array (LEISA), which observes its targets in more than 200 separate wavelengths of infrared light. This color LEISA view of Io (bottom right) combines three wavelength ranges, centered at 1.80, 2.04, and 2.31 micrometers.
The LORRI image (left) shows fine details on Io's sunlit crescent and in the partially sunlit plume from the Tvashtar volcano, and reveals the bright nighttime glow of the hot lavas at the source of the Tvashtar plume. The MVIC image (top right) shows the contrasting colors of the red lava and blue plume at Tvashtar, and the sulfur and sulfur dioxide deposits on Io's sunlit surface. The LEISA image shows that the glow of the Tvashtar volcano is even more intense at infrared wavelengths and reveals the infrared glow of at least 10 fainter volcanic hot spots on the moon's nightside. The brightest of these, Amirani/Maui, which is visible to the lower right of Tvashtar, is less than 4% as bright as Tvashtar. All of these are long-lived hot spots that have been observed previously by the Galileo orbiter. Further analysis of the LEISA data will provide information on the volcanoes' temperatures, and data on the sunlit crescent of Io will reveal details of Io's surface composition.The LORRI, MVIC and LEISA images were taken March 1, 2007, at 00:35, 00:25 and 00:31 Universal Time, respectively, from a range of 2.3 million kilometers (1.4 million miles). The images are centered at Io coordinates 4 degrees south, 164 degrees west.This high-resolution mosaic of images taken by NASA's Galileo spacecraft shows lava flows, bright streaks, and ridged plains at the northern margin of the lava flow field at the volcanic center Prometheus on Jupiter's moon Io. The images, taken during a flyby of Io on February 22, 2000, have a resolution of 12 meters (39 feet) per picture element.
The lava is erupting from a fissure about 40 kilometers (25 miles) east (right) of the edge of this mosaic, and the 100 kilometer (62 mile) tall Prometheus plume is erupting from somewhere near the western end of this mosaic. This mosaic was acquired to search for and image the plume vent or vents. We expected to see a small crater surrounded by radial streaks, but no such central vent can be seen in these or other images. Instead, we see bright streaks along the margins of the lava.
The darkest areas are warm lava flows. Warm lava is dark because it is either too hot or too recent for significant amounts of sulfur-dioxide frost or snow from the plume to have condensed onto it. The blow-up shows two bright dots where hot lava is breaking out of the edge of one of the dark lava flows. The bright, ridged plains to the north of the lava are probably rich in sulfur dioxide. The formation mechanism for the ridges is unclear. The very bright streaks radiating from the area where the lava flows overrun the field are where the hot lava recently vaporized the sulfur dioxide, which then coated the lava-facing sides of the ridges.
The Prometheus plume has been seen by both the Voyager and Galileo spacecraft whenever the viewing geometry has been favorable. While the morphology of the plume has been nearly constant, the plume's position jumped about 80 kilometers (50 miles) between the Voyager observations in the 1970s and the Galileo observations since 1995. The lava flow field has migrated a similar distance. Galileo scientists are currently investigating whether fresh lava breakouts overrunning plains rich in sulfur dioxide can help explain the plume observations.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://solarsystem.nasa.gov/galileo/gallery/index.cfm.
Voir l'image PIA02568: Galileo Takes a Close-up Look at Prometheus sur le site de la NASA.
North is to the top of the picture and the sun illuminates the surface from the left. The image covers an area 1230 kilometers wide and the smallest features that can be discerned are 2.5 kilometers in size. This image was taken on November 6th, 1996, at a range of 245,719 kilometers by the Solid State Imaging (CCD) system on the Galileo Spacecraft.
Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the Galileo mission home page on the World Wide Web at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA00537: Volcanically Active Regions on Io sur le site de la NASA.
Unusual mountains on Jupiter's moon Io are shown in these images that were captured by NASA's Galileo spacecraft during its close Io flyby on October 10, 1999. The top four pictures show four different mountains at resolutions of about 500 meters (1,600 feet) per picture element. The bottom picture is a closeup of another mountain. It is also one of the highest resolution images ever obtained of Io, with a resolution of 9 meters (30 feet) per picture element. The lower resolution images show a range of mountain structures from angular peaks on the left to gentler plateaus, surrounded by very gently sloping debris aprons on the right.
Galileo scientists believe that these images illustrate the deterioration of Ionian mountains. If this is the case, it means that the more angular mountains on the left are younger than the rounded mountains on the right. Almost all of the mountains exhibit ridges parallel to their margins. These ridges indicate material is moving down the sides of the mountains due to gravity. The ridges are similar to structures observed at the base of Olympus Mons on Mars, so comparative studies may help us understand surface processes on both planets. The very high-resolution image shows a closeup of a degraded mountain. This image (which is strikingly different from the other image of comparable resolution which targeted recent lava flows) shows a lumpy landscape. Curiously, the variation in brightness between the dark and light areas within this image is the greatest seen to date on Io. Galileo scientists are continuing to investigate the processes that produce this puzzling surface.
The Sun illuminates the surface from the left in all five images. North is to the top in the top four images. In order to keep the Sun angle consistent in all of the images, north is to the bottom in the bottom image. The upper left image is centered at 18.7 degrees north latitude, 81.4 degrees west longitude, and covers a region 175 kilometers (108 miles) by 170 kilometers (106 miles). The lower left image is centered at about one degree north latitude and 81.7 degrees west longitude and covers a region 135 kilometers (84 miles) by 200 kilometers (124 miles). The middle image is centered at 25.6 degrees north latitude, 96.7 degrees west longitude and covers a region 130 kilometers (81 miles) by 275 kilometers(170 miles). The right image is centered at 14.4 degrees north latitude, 104.7 degrees west longitude and covers a region 125 kilometers (78 miles) by 205 kilometers (130 miles). The bottom image is centered at 4 degrees north latitude and 214.6 degrees west longitude and was taken at a range of 882 kilometers (548 miles).
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA02513: Collapsing Mountains on Io sur le site de la NASA.
NASA's Galileo spacecraft captured this dramatic image of mountains on Io in February 2000.
The image was taken when the Sun was low in the sky, illuminating the scene from the left, so it reveals topographic details of Io's surface. A low scarp, roughly 250 meters (820 feet) high, runs from the upper left toward the center of the image. Mongibello Mons, the jagged ridge at the left of the image, rises 7 kilometers (23,000 feet) above the plains of Io, higher than any mountain in North America.
Few of Io's mountains (see also PIA02526) resemble volcanoes. Instead, Galileo scientists believe that the mountains are formed when blocks of Io's crust are uplifted along thrust faults. Angular mountains are thought to be younger, while older mountains have more subdued topography, such as the rise near the top center of this image.
The image has a resolution of 335 meters (1,100 feet) per picture element. North is to the top of the image.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
Voir l'image PIA03886: Mountains on Io at Sunset sur le site de la NASA.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01067: Changes on Io around Maui and Amirani between Voyager 1 and Galileo's second orbit sur le site de la NASA.
These views of Jupiter's moon Io in the eclipse of the large planet's shadow are color coded so blue to yellow to red represents increasing brightness. The bright spots indicate the locations of volcanic vents on Io, which are spewing hot lava. This image and other data from NASA's Galileo spacecraft indicate that the lava at Pillan Patera (marked Pillan) exceeded 1,700 degrees kelvin (2,600 degrees Fahrenheit) and may have reached 2,000 degrees kelvin (3,140 degrees Fahrenheit). The hottest eruptions on Earth today reach temperatures of about 1,500 kelvin (2,240 degrees Fahrenheit), but hotter lava erupted billions of years ago.
The left and middle parts of this picture show a "raw" image presented without processing other than color coding and labeling. Small, bright pixels and clusters of pixels represent radiation interference. The bright vertical lines are column blemishes in the imaging detector (CCD). An image of Io was acquired through both a 1- micrometer filter (left) and clear filter on the Galileo solid state imaging camera system. Both images were exposed on the same frame; however, during the left exposure, the spacecraft platform moved, causing the exposure to slide toward the clear filter position. The middle view disc combines the two exposures.
The brightest hot spot at Pillan Patera was saturated in both filters, but the platform motion resulted in a horizontal line between the Pillan positions. The unsaturated line allows measurement of Pillan's temperature. For further information, see a report in Science magazine, Vol. 281, July 3, 1998, page 87.
The third view (right) is the processed clear filter data. Diffuse glows, produced by energized particles interacting with gases, highlight both the rim of Io's disc and active plumes such as Marduk. North is to the top of the picture. The resolution is 14.6 kilometers (9 miles) per picture element (pixel), but camera motion smeared the hot spots over about nine pixels. They appear bigger than they really are; modeling indicates the actual hot spots are much smaller than the pixels. The image was taken on June 28, 1997 at a range of 1,440, 000 kilometers (890,000 miles).
JPL manages the Galileo mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo.
Voir l'image PIA01635: Io in Eclipse reveals High Temperature Hot Spots sur le site de la NASA.
This color image, acquired during Galileo's ninth orbit around Jupiter, shows two volcanic plumes on Io. One plume was captured on the bright limb or edge of the moon (see inset at upper right), erupting over a caldera (volcanic depression) named Pillan Patera after a South American god of thunder, fire and volcanoes. The plume seen by Galileo is 140 kilometers (86 miles) high and was also detected by the Hubble Space Telescope. The Galileo spacecraft will pass almost directly over Pillan Patera in 1999 at a range of only 600 kilometers (373 miles).
The second plume, seen near the terminator (boundary between day and night), is called Prometheus after the Greek fire god (see inset at lower right). The shadow of the 75-kilometer (45- mile) high airborne plume can be seen extending to the right of the eruption vent. The vent is near the center of the bright and dark rings. Plumes on Io have a blue color, so the plume shadow is reddish. The Prometheus plume can be seen in every Galileo image with the appropriate geometry, as well as every such Voyager image acquired in 1979. It is possible that this plume has been continuously active for more than 18 years. In contrast, a plume has never been seen at Pillan Patera prior to the recent Galileo and Hubble Space Telescope images.
North is toward the top of the picture. The resolution is about 6 kilometers (3.7 miles) per picture element. This composite uses images taken with the green, violet and near infrared filters of the solid state imaging (CCD) system on NASA's Galileo spacecraft. The images were obtained on June 28, 1997, at a range of more than 600,000 kilometers (372,000 miles).
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA00703: Active Volcanic Plumes on Io sur le site de la NASA.
This picture of Jupiter's volcanic moon Io combines high-resolution black and white images taken by NASA's Galileo spacecraft on October 10, 1999, with lower resolution color images taken by Galileo on July 3, 1999 to help scientists better understand the relationships between the different surface materials and the underlying geologic structures. For example, there is red material, which is often associated with areas where lava is erupting onto the surface and is thought to be a compound of sulfur, around the margin of Monan Patera (the elongated caldera just to the lower right of center). The broad circle of bright, white material (just to the left of center) is thought to be sulfur-dioxide which is being deposited from the plume Amirani.
The lengths of the shadows cast by the mountains make it possible to estimate the mountains¹ heights. The southern mountain on the far right of the mosaic is approximately 8 kilometers (26,000 feet) high and the mountain to the north of it is approximately 4 kilometers (13,000 feet) high.
North is to the top and the image is centered at 22.8 degrees north latitude and 109.5 degrees west longitude. The higher resolution images have a sharpness of about 500 meters (or yards) per picture element and they are illuminated from the left. These images were taken at a range of 25,000 kilometers (15,500 miles). The color images are illuminated from almost directly behind the spacecraft. The color images were taken at a distance of about 130,000 kilometers (81,000 miles) and show a resolution of 1.3 kilometers (0.8 miles) per picture element.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
NASA's Galileo spacecraft acquired its highest resolution images of Jupiter's moon Io on 3 July 1999 during its closest pass to Io since orbit insertion in late 1995. This color mosaic uses the near-infrared, green and violet filters (slightly more than the visible range) of the spacecraft's camera and approximates what the human eye would see. Most of Io's surface has pastel colors, punctuated by black, brown, green, orange, and red units near the active volcanic centers. A false color version of the mosaic has been created to enhance the contrast of the color variations.
The improved resolution reveals small-scale color units which had not been recognized previously and which suggest that the lavas and sulfurous deposits are composed of complex mixtures (Cutout A of false color image). Some of the bright (whitish), high-latitude (near the top and bottom) deposits have an ethereal quality like a transparent covering of frost (Cutout B of false color image). Bright red areas were seen previously only as diffuse deposits. However, they are now seen to exist as both diffuse deposits and sharp linear features like fissures (Cutout C of false color image). Some volcanic centers have bright and colorful flows, perhaps due to flows of sulfur rather than silicate lava (Cutout D of false color image). In this region bright, white material can also be seen to emanate from linear rifts and cliffs.
Comparison of this image to http://www.jpl.nasa.gov/galileo/sepo./atjup/io/color.html">previous Galileo images reveals many changes due to the ongoing volcanic activity.
Galileo will make two close passes of Io beginning in October of this year. Most of the high-resolution targets for these flybys are seen on the hemisphere shown here.
North is to the top of the picture and the sun illuminates the surface from almost directly behind the spacecraft. This illumination geometry is good for imaging color variations, but poor for imaging topographic shading. However, some topographic shading can be seen here due to the combination of relatively high resolution (1.3 kilometers or 0.8 miles per picture element) and the rugged topography over parts of Io. The image is centered at 0.3 degrees north latitude and 137.5 degrees west longitude. The resolution is 1.3 kilometers (0.8 miles) per picture element. The images were taken on 3 July 1999 at a range of about 130,000 kilometers (81,000 miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft during its twenty-first orbit.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo
Voir l'image PIA02308: Global image of Io (true color) sur le site de la NASA.
Nine previously unknown volcanoes have been discovered from this infrared image of Jupiter's moon Io, acquired by NASA's Galileo spacecraft on Oct. 16, 2001.
The infrared image, on the right, serves as a thermal map to a section of Io's surface from pole to pole. An image from Galileo's camera showing the same face of Io (left) is included for correlating the heat-sensing infrared data with geological features apparent in visible wavelengths. The infrared image uses false color to portray the intensity with which the surface glows at the invisible wavelength of 5 microns, as observed by Galileo's near infrared mapping spectrometer instrument. White, reds and yellows indicate hotter regions; blues are cold. The resolution varies from 24 to 39 kilometers (15 to 24 miles) per picture element.
Some of the hot spots visible in this image were not seen in a similar infrared image taken just 10 weeks earlier of an overlapping section of Io.
Three sites of major activity in the images are Prometheus, which is a bright spot at center left; Amirani, which is an elongated feature in the upper right; and the site where a giant plume was erupting in August, which is the bright spot near the top of the image.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/.
Voir l'image PIA03534: Io in Infrared with Giant Plume's New Hot Spot sur le site de la NASA.
The Amirani lava flow on Jupiter's moon Io appears to be made up of many individual flows; the newest flows are the brightest spots in this infrared image from NASA's Galileo spacecraft.
The thermal map from Galileo's near-infrared mapping spectrometer instrument is presented on the left, beside a reference picture of the same area from Galileo's camera. The infrared image uses false color to indicate intensity of glowing at a wavelength of 5 microns. White, reds and yellows indicate hotter regions; blues are cold. North is to the top.
Amirani is the largest active lava flow known in the solar system. Galileo has previously observed many changes in its flows. In this infrared image, Amirani includes the two brightest spots and two others closest to that pair. The image also shows three other active volcanoes on Io: Maui (lower left, corresponding to a dark, roughly circular area in the reference image), Dusurra (top, corresponding to the dark, roughly circular area at the top of the reference image) and an unnamed hot spot that appears as an elongated small feature in the reference image between Dussura and the Amirani flow.
Of Amirani's four bright areas, the one on the lower left corresponds to what is thought to be the flow's vent: a dark elongated crater surrounded by red materials. Red deposits are indicative of recent plume activity on Io. The other three bright areas along the flow correspond to where hot lavas are breaking out.
Notice that the dark flow going from the main flow to the left is not seen in the infrared image. This indicates that this flow has cooled and is no longer active. NASA's Voyager spacecraft detected a plume more than 20 years ago from a location near the end of this now-inactive flow. The plume was probably created by interaction of the hot flow with sulfur-dioxide frost, in the same way as Io's Prometheus plume. Once the flow cooled, the plume shut off.
This infrared image was taken on Aug. 6, 2001. It has a resolution of about 9 kilometers (6 miles) per picture element.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/.
Voir l'image PIA03533: Amirani Lava Flow on Io sur le site de la NASA.
Volcanic hot spots and auroral emissions glow on the darkside of Jupiter's moon Io in the image at left. The image was taken by the camera onboard NASA's Galileo spacecraft on 29 June, 1996 UT while Io was in Jupiter's shadow. It is the best and highest-resolution image ever acquired of hot spots or auroral features on Io. The mosaic at right of 1979 Voyager images is shown with an identical scale and projection to identify the locations of the hot spots seen in the Galileo image. The grid marks are at 30 degree intervals of latitude and longitude. North is to the top.
In the nighttime Galileo image, small red ovals and perhaps some small green areas are from volcanic hot spots with temperatures of more than about 700 kelvin (about 1000 degrees Fahrenheit). Greenish areas seen near the limb, or edge of the moon, are probably the result of auroral or airglow emissions of neutral oxygen or sulfur atoms in volcanic plumes and in Io's patchy atmosphere. The image was taken from a range of 1,035,000 kilometers (about 643,000 miles).
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA00274: Io Glowing in the Dark sur le site de la NASA.
This stereo image of Jupiter's moon Io shows the topography of a region on Io that includes the Zal Patera feature and a mountain or plateau that borders it to the west. It was created by combining two different views taken by NASA's Galileo spacecraft on November 25, 1999 (shown in red) and February 22, 2000 (shown in blue).
A mountain 120 kilometers (75 miles) wide rises to the west of the patera, a dark volcanic depression. By measuring the shadow, scientists were able to determine that the eastern margin of this mountain is about 1.5 kilometers (5000 feet) high. To the west and northwest, the mountain's margins are scalloped, which may indicate that a process called sapping is eroding them. Sapping occurs when fluid escapes from the base of a cliff, causing the material above it to collapse. Along the northwestern margin, the rough material at the base of the cliff maybe debris left over from the sapping process. Dark lava flows can be seen coming from a fissure to the east of the mountain.
Galileo scientists are in the process of generating topographic maps from these images. Such maps will reveal the heights and slopes of different landforms in this region, which will help scientists determine the strength and other properties of Io's surface materials. They will also be useful in understanding the processes of uplift and erosion on Io.
The picture is centered at 42.3 degrees north latitude and 76.9 degrees west longitude. North is to the top of the picture. The observations used to make the stereo image were made at ranges of 26,000 and 33,500 kilometers (16,200 and 20,900 miles) from Io. The resolution of the stereo image is about 335 meters (370 yards) per picture element.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://solarsystem.nasa.gov/galileo/gallery/index.cfm.
Voir l'image PIA02553: Stereo Image of Zal Patera and Neighboring Mountain, Io sur le site de la NASA.
The Galilean satellite Io floats above the cloudtops of Jupiter in this image captured on the dawn of the new millennium, January 1, 2001 10:00 UTC (spacecraft time), two days after Cassini's closest approach. The image is deceiving: there are 350,000 kilometers -- roughly 2.5 Jupiters -- between Io and Jupiter's clouds. Io is the size of our Moon, and Jupiter is very big.
Voir l'image PIA02879: A New Year for Jupiter and Io sur le site de la NASA.
North is to the top of the picture and the sun illuminates the surface from the left. The image covers an area about 2600 kilometers wide and the smallest features that can be discerned are 3.5 kilometers in size. This image was taken on November 6th, 1996, at a range of 339,400 kilometers by the Solid State Imaging (CCD) system on the Galileo Spacecraft.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01103: Geologic Landforms on Io (Area 1) sur le site de la NASA.
North is to the top of the images. The left frame was acquired on April 4th, 1997, while the right frame was taken on Sept. 19th, 1997. The images were obtained at ranges of 563,000 kilometers (350,000 miles) for the left image, and 505,600 kilometers (314,165 miles) for the right.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo...
Voir l'image PIA00744: Arizona-sized Io Eruption sur le site de la NASA.
North is to the top of the picture and the sun illuminates the surface from the left. The bright region beyond Io's limb (upper right corner) is Jupiter's atmosphere. The image covers an area about 2080 kilometers wide and the smallest features that can be discerned are 2.6 kilometers in size. This image was taken on November 6th, 1996, at a range of 258,100 kilometers by the Solid State Imaging (CCD) system on the Galileo Spacecraft.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA01104: Geologic Landforms on Io (Area 2) sur le site de la NASA.
The Tvashtar plume on Io, seen by the Hubble Space Telescope (HST) and by New Horizons.
(A): The image in which the plume was discovered, taken by HST in ultraviolet light on Feb. 14, 2007, at a wavelength of 260 nm. The red diamond indicates location of the Tvashtar hot spot seen later by New Horizons. (B): An HST image of Io and the Tvashtar plume seen against Jupiter; sulfur gas in the plume absorbs ultraviolet light, making the plume look reddish in this color composite. The composite is composed of images taken at 260 nm (blue), 330 nm (green), and 410 nm (red). Other images in this montage are in visible light from the Long-Range Reconnaissance Imager (LORRI). The scale bar is 200 kilometers long and the yellow star indicates the projected location of the hot spot at the Tvashtar plume source. The dashed line is the terminator, the line dividing day from night on Io. (C): The highest-resolution view of the full plume, at a resolution of 12.4 kilometers (7.7 miles) per pixel and a solar phase angle of 102 degrees, showing the complex filamentary structure of the plume. The images are sharpened by un-sharp masking; the dark line at the edge of the disk is an artifact of this sharpening. (D): An image at 145-degree phase angle at 22.4 kilometers (13.8 miles) per pixel, showing the time variability of the details of the plume structure and its persistent bright top. (F-J): Sequence of frames at 2-minute intervals showing dynamics in the upper part of the plume (the source is on the far side of Io). Colored diamonds track individual features whose speeds, projected on the plane of the sky, are shown in (E).
This image appears in the Oct. 12, 2007, issue of Science magazine, in a paper by John Spencer, et al.
These images from NASA's Galileo spacecraft show changes in the largest active field lava flows in the solar system, the Amirani lava flow on Jupiter's moon Io. Scientists have identified 23 distinct new flows by comparing the two images taken 134 days apart, on Oct. 11, 1999, and Feb. 22, 2000.
The Amirani lava-flow field spans more than 300 kilometers (190 miles). Individual flows within it are each several kilometers or miles long, which is about the size of the entire active eruption on Kilauea, Hawaii. In total, the new lava flows at Amirani covered about 620square kilometers (240 square miles) of Io in less than five months. By comparison, Kilauea covered only about 10 square kilometers (4 square miles) in the same time. Amirani is huge even when compared to other Ionian lava flows: The Prometheus lava flow field covered only about 60square kilometers (24 square miles) during this time.
Galileo scientists are studying Amirani to understand how such large lava flows are created. The last eruption this size on Earth happened about 15 million years ago along the Columbia River in what is now the state of Washington. Many scientists thought that such long lava flows were formed in violent volcanic outbursts. However, the eruption observed at Amirani is relatively calm, despite the fact that over 100tons of lava are disgorged every second. Galileo's observations of Io indicate that huge, ancient lava flows on the Earth, such as the Columbia River flood basalts, could also have formed in relatively tranquil eruptions.
The color image on the left is a composite of black-and-white images collected on Feb. 22, 2000, at a resolution of 210 meters (690 feet) per picture element, and color images collected on June 30, 1999, at 1.3 kilometers (0.8 mile) per picture element. The white boxes and arrows show the locations of the areas analyzed in detail on the right. The left-hand pair of black-and-white images, labeled I24, are parts of a mosaic collected on Oct. 11, 1999, at 500 meters (550 yards) per picture element. The center pair of images, labeled I27, shows what the same areas looked like on Feb. 22, 2000. These later images are about twice as sharp as the earlier images, making some features that did not change appear crisper. In order to demonstrate the real changes, the I27 images were divided by the I24 images, producing the pair of ratio images on the right. The new dark lava that erupted between October 1999 and February 2000 has been highlighted in red.
Images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://solarsystem.nasa.gov/galileo/gallery/index.cfm.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C.
Voir l'image PIA02585: Amirani's Big Lava Flow on Io sur le site de la NASA.
This image shows one of many intriguing mountains on Jupiter's moon Io. The image was made by combining a recent high-resolution, black and white image with earlier low-resolution color data to provide a high-resolution, color view. NASA's Galileo spacecraft took both images.
The 240-kilometer (150-mile) long mountain in the image is south of the volcanic hot spot named Zal. The black and white version of this image was useful for showing the shape of the mountain and the small fans of debris piled against the base of its tall, steep cliffs. However, when colorized the relationship between different types of materials becomes apparent. For example, the bright, red material is believed to contain a compound of sulfur that forms when sulfur is boiled at a high temperature. Active eruptions of molten rock (lava) are the most likely source for the heat. Thus we see red sulfur where lava reaches the surface. Other sulfur compounds cover the yellow areas, and the black areas are fresh silicate lava that has not yet been coated by the yellow sulfurous materials. The green patches are still somewhat mysterious; they appear to form when red sulfur lands on warm lava and the two react in a manner that is still unknown.
In this image, it is clear that the red material has blown out of a long crack along the western side of the mountain. Lava has flowed from this crack and filled a depression (caldera). Some of the red sulfur close to the dark caldera appears to have been converted into green material. The fact that lava comes up along the faults that define the sides of the mountains provides important clues to how the mountains form and the state of the interior of Io. Scientists at the University of Arizona speculate that the formation of the mountains on Io may be related to plumes of hot material rising inside the fiery body of Io.
North is to the top and the setting sun is shining from the west. The image is centered at about 33 degrees north, 72 degrees west. The high-resolution image was taken on February 22, 2000 by NASA's Galileo spacecraft. The image was taken by the Galileo's onboard camera from a range of 33,500 kilometers (20,800 miles) and has a resolution of 335 meters (1,100 feet) per picture element. The color images were taken on July 3, 1999. They have resolutions of 1.3 kilometers (0.81 miles) per picture element and are illuminated from almost directly behind the spacecraft. They were taken at a distance of about 130,000 kilometers(81,000 miles) from Io.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the Galileo mission home page at http://solarsystem.nasa.gov/galileo/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/gallery/io.cfm.
North is to the top of this picture which merges images obtained with the clear, red, green, and violet filters of the solid state imaging (CCD) system on NASA's Galileo spacecraft. The resolution is 6.1 kilometers per picture element. The images were taken on April 4th, 1997 at a range of 600,000 kilometers.
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).
Concurrent results from Galileo's exploration of Io appear in the October 15th, 1997 issue of Geophysical Research Letters. The papers are: Temperature and Area Constraints of the South Volund Volcano on Io from the NIMS and SSI Instruments during the Galileo G1 Orbit, by A.G. Davies, A.S. McEwen, R. Lopes-Gautier, L. Keszthelyi, R.W. Carlson and W.D. Smythe. High-temperature hot spots on Io as seen by the Galileo Solid-State Imaging (SSI) experiment, by A. McEwen, D. Simonelli, D. Senske, K. Klassen, L. Keszthelyi, T. Johnson, P. Geissler, M. Carr, and M. Belton. Io: Galileo evidence for major variations in regolith properties, by D. Simonelli, J. Veverka, and A. McEwen.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at http://www.jpl.nasa.gov/galileo/sepo..
Voir l'image PIA00738: Topography and Volcanoes on Io (color) sur le site de la NASA.
