The Mars Global Surveyor Mars Orbiter Camera (MOC) wide angle system is used to monitor changes in martian weather and the seasonal coming and going of polar frost. These four wide angle pictures of craters in both the northern and southern middle and polar latitudes of Mars show examples of frost monitoring conducted by the MOC in recent months. It is spring in the northern hemisphere, and frost that accumulated during the most recent 6-month-long winter has been retreating since May. Examples of frost-rimmed craters include Lomonosov (top, left) and an unnamed crater farther north (top, right). The unnamed crater has a patch of frost on its floor that--based on how it looked during the 1970s Viking missions--is expected to persist through summer. It is autumn in the southern hemisphere, and frost was seen as early as August in some craters, such as Barnard (bottom, left); later the frost line moved farther north, and we began to see frost in Lowell Crater (bottom, right) in mid-October. For a view of what Lomonosov Crater looked like during northern winter, see "The Frosty Rims of Lomonosov Crater in Winter."
This is a series of 4 images. Each image is a composite of two pictures obtained at the same time, a red wide angle view and a blue wide angle view. In each picture, north is toward the top and sunlight illuminates the scene from the upper left (for southern hemisphere) or lower left (for northern hemisphere).
Voir l'image PIA02836: The Frosted Craters of Northern Spring and Southern Autumn - Lowell Crater sur le site de la NASA.
In the middle of January 2001, Mars Global Surveyor (MGS) completed one Mars year in its ~380 km-high (236 mi) mapping orbit. The mapping orbit was originally achieved in late February 1999. In March of that year, MGS conducted a series of operations in preparation for full-up mapping, first calibrating its scientific instruments and then operating in a mode in which the high gain antenna was held fixed against the body of the spacecraft. During this Fixed High Gain Antenna period, "contingency science" observations were made in case the high gain antenna failed to properly deploy. The wide angle view of the martian north polar cap shown on the left was acquired on March 13, 1999, during early northern summer. The image on the right was acquired almost exactly one Mars year later, on January 26, 2001. The light-toned surfaces are residual water ice that remains through the summer season. The nearly circular band of dark material surrounding the cap consists mainly of sand dunes formed and shaped by wind. The north polar cap is roughly 1100 kilometers (680 miles) across. Close inspection will show that there are differences in the frost cover between the two images (for example, in the upper center of each image, and on the left edge center). Although these changes appear small, they are in fact quite large--the change in frost covering is equivalent to the amount of frost that would be evaporated (in the case of areas that are darker) or deposited (in areas where frost is still on the ground) in almost 5 months. What gives rise to such large changes in the heat budget for the polar caps from one year to the next is not known. Changes in the coloration and brightness of the polar cap suggest dust, deposited perhaps by dust storms during critical periods of the year, may play an important role.
Voir l'image PIA03204: The Martian North Polar Cap in Summer - One Year Later sur le site de la NASA.
Southern spring on Mars began with a "bang" in late June 2001 with a series of large dust storms that in some regions were still occurring each day well into September. By early July, the martian atmosphere was so hazy that opportunities for high resolution imaging of the planet were very limited. This wide angle camera view obtained by the Mars Global Surveyor Mars Orbiter Camera shows a large dust-raising event that occurred on July 8, 2001, as cold, raging winds blew off the frozen south polar cap (bottom) and rushed toward the network of troughs known as Labyrinthus Noctis near the martian equator (center). A second, smaller dust storm can be seen near the top just left of center, northwest of the Ascraeus Mons volcano (uppermost dark elliptical feature). To give a sense of scale, Ascraeus Mons is large enough to nearly cover the state of Washington, home of the famous (and much smaller) Mount St. Helens volcano. Sunlight illuminates the scene from the left, and north is toward the upper right.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Voir l'image PIA03168: Snapshot of Southern Spring Dust Storm Activity sur le site de la NASA.
This is the dusty time of year for Mars. The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) team has been anticipating for months that late June through July 2003 will be a time of large dust storms and considerable haze. As June turned to July, several large dust storms began popping up. Two examples are shown here in this mosaic of MOC daily global images from June 29, 2003. Near the center of this picture is a large dust storm engulfing southern Isidis Planitia. Toward the upper right (northeast) of the Isidis storm is another event in northern Elysium Planitia.
This view of a portion of Mars is illuminated by sunlight from the left. This is a simple cylindrical map projection, north is up. The large dark feature just left of center is Syrtis Major; the bright oval toward the bottom left is the giant Hellas impact basin, which is more than 2,000 km (more than 1200 miles) across. The white area at the bottom of the picture is the south polar seasonal frost cap, made up mostly of carbon dioxide. The wispy features at the top of the image are clouds over the martian northern plains.
Voir l'image PIA04615: Time for Dust Storms sur le site de la NASA.
The Libya Montes are a ring of mountains up-lifted by the giant impact that created the Isidis basin to the north. During 1999, this region became one of the top two that were being considered for the now-canceled Mars Surveyor 2001 Lander. The Isidis basin is very, very ancient. Thus, the mountains that form its rims would contain some of the oldest rocks available at the Martian surface, and a landing in this region might potentially provide information about conditions on early Mars. In May 1999, the wide angle cameras of the Mars Global Surveyor Mars Orbiter Camera system were used in what was called the "Geodesy Campaign" to obtain nearly global maps of the planet in color and in stereo at resolutions of 240 m/pixel (787 ft/pixel) for the red camera and 480 m/pixel (1575 ft/pixel) for the blue. Shown here are color and stereo views constructed from mosaics of the Geodesy Campaign images for the Libya Montes region of Mars. After they formed by giant impact, the Libya Mountains and valleys were subsequently modified and eroded by other processes, including wind, impact cratering, and flow of liquid water to make the many small valleys that can be seen running northward in the scene. The pictures shown here cover nearly 122,000 square kilometers (47,000 square miles) between latitudes 0.1°N and 4.0°N, longitudes 271.5°W and 279.9°W. The mosaics are about 518 km (322 mi) wide by 235 km (146 mi) high. Red-blue "3-D" glasses are needed to view the stereo image.
Voir l'image PIA02396: A Regional View of the Libya Montes sur le site de la NASA.
In both of the two images shown above, north is to the top. In the MOC image, the camera was viewing towards the west.
The left image is excepted from a U.S. Geological Survey shaded relief map, showing the footprint of the MOC wide angle color image. The large canyon system (Valles Marineris) spans this view; chaotic terrain is seen at the far right and the eastern-most of the four large Tharsis volcanoes (Ascraeus Mons) is shown in upper left.
The right image is the composite of MOC frames P013_01 and P013_02. Because the MOC acquires its images one line at a time, the cant angle towards the sun-lit portion of the planet, the spacecraft orbital velocity, and the spacecraft rotational velocity combine to distort the image slightly. However, the wide angle cameras provide a fairly realistic portrayal of what one would see looking out across Mars from the Orbiter. Notable in this image are the late afternoon clouds and hazes that are concentrated within the canyon system. This image is available at higher resolution as PIA00991.
Launched on November 7, 1996, Mars Global Surveyor entered Mars orbit on Thursday, September 11, 1997. From the planned 400 km (248 mi) orbit altitude, MOC wide angle images will be 2-4 times higher resolution than these pictures.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Voir l'image PIA00992: Valles Marineris sur le site de la NASA.
Mars Global Surveyor was presented with a unique opportunity February 13-18, 1998, to image sunlight glinting off of the surface and atmospheric haze of Mars. Orbits 130-137 were devoted to obtaining MOC images of this effect, also known as opposition surge. During each orbit in mid-February, the Mars Global Surveyor spacecraft passed close to and through the line between the Sun and the center of Mars. In other words, the phase angle (angle between the Sun's incident light and the direction from the surface to the spacecraft) was near zero degrees. The sunlight reflecting from Mars near the zero phase angle produces the rare sun-glint phenomenon. The size and brightness of the glint depends on the physical properties of the surface (dust, sand, and rock distribution) and the atmosphere (haze/suspended dust). Studies of these images are expected to yield important information that can be compared with thermal emission observations.
The picture is a color composite of MOC images 13601 (red wide angle) and 13602 (blue wide angle). The green-color band is synthesized from the red and blue using a relationship well-understood from Viking images of the late 1970s. The large, dark region near the top-center of the picture is Sinus Meridiani. The circular feature at the upper right is the impact basin, Schiaparelli. The opposition surge feature --the sun glint-- is centered around 21.0°S latitude, 4.1°W longitude.
The two images were taken on Mars Global Surveyor's 136th orbit on February 18, 1998. Orbit 136 was the second-to-last orbit on which MOC obtained images of Mars during the first aerobraking phase (AB-1) of the mission. MOC was off between the end of AB-1 on February 19, 1998, until the start of Science Phasing Orbit-1 phase (SPO-1), which began March 28 and ended April 28, 1998.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Voir l'image PIA01432: Opposition Surge: Sunlight Glinting off Mars sur le site de la NASA.
This image is TES thermal data (Orbit 222) overlayed on the MOLA DEM. The color scale is TES T18-T25, which is a cold spot index. The grey scale is MOLA elevation in kilometers. Most cold spots can be attributed to surface spectral emissivity effects. Regions that are colored black-violet-blue have near unity emissivity and are coarse grained CO2. Regions that are yellow-red are fined grained CO2. The red-white spot located approximately 300W85N is our most likely candidate for a CO2 snow storm.
This composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle daily global images shows a north polar dust storm on March 7, 2003. Similar late summer storms occurred nearly every day from late February well into April 2003; these were also seen in late summer in 1999 and 2001. The white features at the top of the image are the water ice surfaces of the north polar residual cap. Sunlight illuminates the scene from the lower left.
Voir l'image PIA04468: North Polar Dust Storm sur le site de la NASA.
This is a still from an animation showing the Mars Exploration Rover Spirit's ultimate target, the "Columbia Hills," from various angles including a Spirit's-eye-view, a fly-over view, a horizon view and a counterclockwise view circling to the south and north of the hills. The Columbia Hills are an intriguing target because they are older than the plains and may give scientists more clues to Mars' past. To successfully reach and examine the hills, Spirit must continue to perform above the original expectations of scientists and engineers. The elevation model in this animation was made using two images from the camera onboard NASA's Mars Global Surveyor.
Planum Australe--the Plains of the South. Patchy frost lingers late into Martian spring in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle view from November 25, 1999. Spring would give way to summer in only 1 month, on December 25, 1999. The surfaces underneath the frost have different properties--some get warmer while others stay cold--thus causing frost to linger on colder surfaces and sublime away from warmer surfaces, leaving the dazzling, almost psychedelic pattern seen at the center of this image. Circular features in this view are old craters formed by meteor impact. The brightest patches within most of these circles are fields of sand dunes covered by frost. The center of this scene is near 78°S, 135°W; north is toward the upper right. Illumination is from the upper left. The image covers an area 110 km (68 mi) across by 590 km (367 mi) down. This is a color composite of MOC wide angle camera images M09-06029 (red) and M09-06030 (blue). To see what the raw MOC image data look like, visit the newest data releases (for Mission Subphases M07 - M12, covering September 1999 through February 2000) in the MOC GALLERY.
Voir l'image PIA02812: Spring Thaw in Northwestern Planum Australe sur le site de la NASA.
This month (April 1999), the Mars Global Surveyor Mars Orbiter Camera (MOC) passed over the Apollinaris Patera volcano and captured a patch of bright clouds hanging over its summit in the early martian afternoon. This ancient volcano is located near the equator and--based on observations from the 1970s Viking Orbiters--is thought to be as much as 5 kilometers (3 miles) high. The caldera--the semi-circular crater at the volcano summit--is about 80 kilometers (50 miles) across.
The color in this picture was derived from the MOC red and blue wide angle camera systems and does not represent true color as it would appear to the human eye (that is, if a human were in a position to be orbiting around the red planet). Illumination is from the upper left.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
7 November 2006
Mars Global Surveyor (MGS) was launched 10 years ago today, on 7 November 1996. The spacecraft reached Mars on 12 September 1997, and has been observing the ever-changing red planet over the course of the past 5 martian years.
The Mars Orbiter Camera (MOC) has spent 10 years in the near vacuum of space-not bad, considering that the Primary Mission, at the time of launch, was expected to end in early 2000. Since September 1997, MOC has been acquiring new images that highlight the geology and meteorology of Mars; more than 240,000 images have been returned to Earth. A recent example, from 15 October 2006, is shown here.
Two annular (i.e., somewhat circular) clouds are seen in the upper left corner of this mosaic of MOC wide angle camera daily global mapping images. To the right of the picture's center is the martian north polar cap. The image has a scale of about 7.5 kilometers (4.7 miles) per pixel. Annular clouds are common in mid-northern summer in the north polar region, and may result from eddy currents in the lower atmosphere. The appearance of such clouds happens every year; this year they came like clockwork within a two-week forecasted period, based on the previous 4 martian years of experience gained from MGS MOC daily global imaging.
Despite their superficial resemblance to Earth-orbiting satellite views of hurricanes, these cloud features are not the result of strong winds, and they typically dissipate later in the day. The pictures used to make this mosaic were acquired less than 2 days before the MOC was turned off for MGS's fifth Mars-Earth Solar Conjunction period. During Conjunction, Mars was on the other side of the Sun, relative to Earth, and thus MGS could not transmit data (through the Sun) during the second half of October.
Examples of north polar annular clouds seen in previous Mars years were featured by the MGS MOC team in September 2005: "Celebrating 8 Years at Mars: Repeated Weather Events." To review the MGS launch of 10 years ago, one can visit the NASA Kennedy Space Center web site, which includes pictures and video at: http://science.ksc.nasa.gov/payload/missions/mgs/video.html. Video clips of the launch and many movies and videos from the earlier phases of the MGS mission can be reviewed at the Jet Propulsion Laboratory web site at:
Voir l'image PIA01887: MGS Mars Orbiter Camera: 10 Years In Space sur le site de la NASA.
With the release this month (October 2002) of the latest installment of 18,812 images, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) passes another major milestone: more than 100,000 images have been validated and archived with the NASA Planetary Data System. The total number of archived images now available on-line is 112,218--more than twice the number of pictures acquired by the two Viking orbiters in 1976-1980. These pictures, from MOC extended mission subphases E07 through E12, were acquired August 2001 through January 2002. Every six months, after a six-month, labor-intensive archiving effort, the MOC team releases six months-worth of validated data to the NASA Planetary Data System.
Mars Global Surveyor is now in its sixth year orbiting the red planet. MGS reached Mars on 12 September 1997. The first MOC images were obtained on 15 September 1997.
The two pictures shown here were taken by the MOC narrow angle (high resolution) camera and "colorized" by applying the colors of Mars obtained by the MOC wide angle cameras. Both pictures show gullies on the walls of two different meteor impact craters that occur in Newton Basin in Sirenum Terra, Mars. The picture on the left, showing gullies in a crater at 42.4°S, 158.2°W, exhibits patches of wintertime frost on the crater wall, and dark-toned sand dunes on the floor. The picture on the right, from a crater at 39.0°S, 166.1°W, is one of the highest-resolution images obtained from Mars. Its resolution is 1.5 meters (5 feet) per pixel--objects the size of school buses can be resolved in the full size image. The gullies in these craters originate at a specific layer and may have formed by release of groundwater to the martian surface in geologically recent times.
MOC data from E07 through E12 include many exciting observations of the 2001 planet-enshrouding dust storm events, springtime retreat of the south polar seasonal frost cap, hundreds of images designed to monitor the retreat of carbon dioxide ice cliffs in the south polar residual cap, images obtained to look for changes and stereo views of gullies, pictures of proposed and potential Mars Exploration Rover landing sites, and more. Several previous MGS MOC releases highlighted these diverse E07-E12 observations:
PIA03169
Springtime on the Martian South Polar CapPIA03170
The 2001 Great Dust Storms - Hellas/Syrtis MajorPIA03171
The 2001 Great Dust Storms - TharsisPIA03178
MOC's 100,000th ImagePIA03179
MOC Observes Changes in the South Polar Cap: Evidence for Recent Climate Change on MarsPIA03471
Changes in South Polar Carbon Dioxide Ice CapPIA03472
Stereo View of Layer Outcrops in Iani ChaosPIA03753
Gullies and Streaks on Crater wall KaiserPIA03496
Southern Hemisphere Polygonal Patterned GroundPIA03918
"Inca City" is Part of a Circular Feature
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Voir l'image PIA03872: 18,812 New MGS MOC Images Archived and Online sur le site de la NASA.
This overview map made from Mars Orbiter camera images illustrates the path that the Mars Exploration Rover Opportunity has taken from its first sol on the red planet through its 87th sol. After thoroughly examining its "Eagle Crater" landing-site, the rover moved onto the plains of Meridiani Planum, stopping to examine a curious trough and a target within it called "Anatolia." Following that, Opportunity approached and remotely studied the rocky dish called "Fram Crater." As of its 91st sol (April 26, 2004), the rover sits 160 meters (about 525 feet) from the rim of "Endurance Crater."
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle camera view of the martian south polar residual cap was acquired in March 2002, at the peak of the last southern summer. The ice at the surface of this summertime cap is mostly composed of carbon dioxide. The picture covers an area about 600 km (373 mi) wide near 90.0°S. Sunlight illuminates the scene from the lower right. Compare the view shown here with the appearance of the cap 1 Mars year earlier in April 2000 by visiting: MOC2-225, 27 April 2000, "South Polar Cap, Summer 2000".
Voir l'image PIA04566: South Polar Cap in Summer sur le site de la NASA.
Approximately 2.6 million of these laser pulse measurements were assembled into a topographic grid of the north pole with a spatial resolution of 0.6 miles (one kilometer) and a vertical accuracy of 15-90 feet (5-30 meters).
The principal investigator for MOLA is Dr. David E. Smith of Goddard. The MOLA instrument was designed and built by the Laser Remote Sensing Branch of Laboratory for Terrestrial Physics at Goddard. The Mars Global Surveyor Mission is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for the NASA Office of Space Science.
Voir l'image PIA01337: Laser Provides First 3-D View of Mars' North Pole sur le site de la NASA.
November 13, 2003
Details in a fan-shaped deposit discovered by NASA's Mars Global Surveyor orbiter provide evidence that some ancient rivers on Mars flowed for a long time, not just in brief, intense floods.
The apron of debris filling the middle of this picture from the spacecraft's Mars Orbiter Camera is a hardened and eroded distributory fan, a type of geological feature that includes river deltas and alluvial fans. Sediments transported through valleys by water on early Mars formed the 13-kilometer-long (8-mile) deposit in the distant past, when it was still possible for liquid water to flow across the martian surface.
Mars Orbiter Camera team members published discovery of this feature in the online edition of the journal Science. What is important about it? First, it provides unequivocal evidence that some valleys on Mars experienced persistent flow over considerable periods of time, as rivers do on Earth. Second, because the fan is today a deposit of sedimentary rock, it demonstrates that some sedimentary rocks on Mars were deposited in a liquid environment. Third, the fan's general shape, the pattern of its channels, and its low slopes provide circumstantial evidence that the feature was an actual delta -- that is, a deposit made when a river or stream enters a body of water. If so, this landform is a strong indicator that some craters and basins on Mars once held lakes. Hundreds of other locations on Mars where valleys enter craters and basins have been imaged by the Mars Orbiter Camera, but none has shown landforms like those presented here.
The picture is a mosaic of images acquired between August 2000 and September 2003. The area covered 14 kilometer (8.7 miles) by 19.3 kilometers (12 miles). North is up. Sunlight illuminates the scene from the left. The spacecraft's narrow-angle camera takes grayscale images; the color added is based on information from a camera on Mars Odyssey. The fan is in an unnamed crater that is 64 kilometers (40 miles) in diameter, at 24.3 degrees south latitude, 33.5 degrees west longitude. The crater lies northeast of a larger one named Holden Crater.
The fan is a fossil landform. That is, it is an eroded remnant of a somewhat larger and thicker deposit. The originally loose sediment was turned to rock and then eroded over time to present the features seen today. The channels through which sediment was transported are no longer present. Instead, only their floors remain, and these have been elevated by erosion so that former channels now stand as ridges. The floors of former channels became inverted in this way because they were more resistant to the forces of erosion, indicating they either were more strongly cemented than surrounding materials, or they have more coarse grains (which are harder to remove), or both.
Closer looks at two portions of the fan show observations critical to the story. White boxes overlaid on the image show the locations of those two areas.
Click on image for larger view
A region near the center of the fan has a loop, the inverted floor of a former meandering stream that was cut off as the channel adjusted its course. Meanders and cut-off meanders are the prime evidence for persistent flow of water through this area sometime early in martian history.
Click on image for larger view
A region near the southeast edge of the fan shows inverted channels at different levels within the sedimentary deposit, indicating a long and complex history of water-related processes. One ridge crosses over another just left of the center of this frame. The top of the lower ridge is the former floor of a channel that was transporting water and sediment toward the lower right. The top of the upper ridge was once the floor of a channel that moved material toward the right or upper right. The lower ridge is the older channel. It was completely filled and buried beneath the surface when the upper channel formed.
Click on image for larger view
A regional context image shows the location of the fan with a white box. West of the fan are several valleys that fed water and sediment to the crater holding the fan (labeled "Holden NE" Crater). This map is a mosaic of daytime infrared images from the Thermal Emission Imaging System on Mars Odyssey. The contours are topography relative to Mars' zero-elevation level, derived from observations by the Mars Orbiter Laser Altimeter on Mars Global Surveyor. Sunlight illuminates the scene from the upper left. The 10-kilometer scale bar is about 6.2 miles across.
Click on image for larger view
Additional information about Mars Global Surveyor is online at http://mars.jpl.nasa.gov/mgs/. The Jet Propulsion Laboratory, Pasadena, Calif., manages the Mars Global Surveyor mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena. JPL's industrial partner is Lockheed Martin Space Systems, Denver, which built and operates the spacecraft.
Voir l'image PIA04869: Distributory Fan Near Holden Crater sur le site de la NASA.
As has been noted in other MOC releases, Olympus Mons is the largest of the major Tharsis volcanoes, rising 25 km (15.5 miles) and stretching over nearly 550 km (340 miles) east-west. The summit caldera, a composite of as many as seven roughly circular collapse depressions, is 66 by 83 km (41 by 52 miles) across. Also seen in this image are water-ice clouds that accumulate around and above the volcano during the late afternoon (at the time the image was acquired, the summit was at 5:30 PM local solar time). To understand the value of orbital observations, compare this image with the two taken during approach (PIA00929 and PIA00936), that are representative of the best resolution from Earth.
Through Monday, October 28, the MOC had acquired a total of 132 images, most of which were at low sun elevation angles. Of these images, 74 were taken with the high resolution narrow angle camera and 58 with the low resolution wide angle cameras. Twenty-eight narrow angle and 24 wide angle images were taken after the suspension of aerobraking. These images, including the one shown above, are among the best returned so far.
Launched on November 7, 1996, Mars Global Surveyor entered Mars orbit on Thursday, September 11, 1997. The original mission plan called for using friction with the planet's atmosphere to reduce the orbital energy, leading to a two-year mapping mission from close, circular orbit (beginning in March 1998). Owing to difficulties with one of the two solar panels, aerobraking was suspended in mid-October and is scheduled to resume in mid-November. Many of the original objectives of the mission, and in particular those of the camera, are likely to be accomplished as the mission progresses.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Voir l'image PIA00993: Olympus Mons in Color sur le site de la NASA.
Images from Mariner 9 in 1972 revealed that some of the mesas and mounds found within the chasms of the martian "Grand Canyon"--the Valles Marineris--have layers in them. Speculations as to the origin of these interior layered materials ranged from volcanic ash deposits to sediments laid down in lakes that could have partially filled the Vallis Marineris troughs, much as lakes now occupy portions of the rift valleys of eastern Africa. The proposal that the Valles Marineris once hosted deep martian lakes led to additional speculation as to the prospects for finding fossil evidence of martian life.
Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images have ten or more times better resolution than the Mariner 9 and Viking orbiter images taken in the 1970s. MOC images have indeed confirmed the presence of layered outcrops within the Valles Marineris. They have also shown places previously not suspected to have layered rock, and they have shown that these materials might not have formed in the Valles Marineris, but were instead deposited in craters that were subsequently buried long before the chasms opened up (see discussion below). The layered rock is now visible because of faulting and erosion.
The high resolution picture shown here (B, above right) was the first image received by MOC scientists that began to hint at a larger story of layered sedimentary rock on Mars. The picture shows a 1.5 km by 2.9 km (0.9 mi by 1.8 mi) area in far southwestern Candor Chasma (A, above left) that was--based on Mariner 9 and Viking orbiter images--not previously expected to exhibit layers. The MOC image reveals that the floor of western Candor Chasma at this location is indeed layered. What is most striking about the picture is the large number and uniformity of the layers, or beds. There are over 100 beds in this area, and each has about the same thickness (estimated to be about 10 meters (11 yards) thick). Each layer has a relatively smooth upper surface, and each is hard enough to form steep cliffs at its margins.
Layers indicate change. The uniform pattern seen here--beds of similar properties and thickness repeated over a hundred times--suggest that the deposition of materials that made the layers was interrupted at regular or episodic intervals. Patterns like this, when found on Earth, usually indicate the presence of sediment deposited in dynamic, energetic, underwater environments. On Mars, these same patterns could very well indicate that the materials were deposited in a lake or shallow sea. Other MOC images suggest that these layers would not have formed in a lake in Candor Chasma, but instead were deposited in a crater or other basin that existed before Candor Chasma was cut (by faulting and erosion) into the surrounding terrain. However, it is not known for certain that these materials actually formed underwater, for it is possible that there were uniquely Martian processes occurring in the distant past that would mimic the pattern of sedimentation in water. For example, if the early Martian atmosphere was denser than it is today, and if the planet's atmospheric pressure changed on a cyclic basis (as it does today), then perhaps these materials are simply deposits of airborne dust that were later buried and cemented to create cliff-forming rock.
Sunlight illuminates both the wide angle context view and the narrow angle high resolution image from the left/upper left. In both, north is toward the top and east to the right.
Voir l'image PIA02839: Layered Outcrops of Far West Candor Chasma sur le site de la NASA.
Hundreds of layers of similar thickness, texture, and pattern have been exposed by erosion in a 64 kilometer-wide (40 mile-wide) impact crater in western Arabia Terra at 8°N, 7°W. In other words, these layers provide a record of repeated, episodic changes that took place at some time far in the martian past, when this particular impact crater was the site of sediment deposition. Layers toward the center of the crater are nearly horizontal, but those closer to or draping over the crater walls are tilted (geologist use the term dipping) toward the basin center. These relationships suggest that the sediments that created these layers were deposited from above--perhaps by settling out of the martian atmosphere, or perhaps by settling out of water that might have occupied this crater as a lake.
The context view (above) was taken by the Viking 1 orbiter in 1978; in it, north is up and sunlight illuminates the scene from the right. The three Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) narrow angle (high resolution) views (PIA02840, PIA02841, PIA02842 (this release)) sample layer outcrops that were previously not known to exist in this crater. Each MOC image is illuminated from the left. Dark material in PIA02841 and PIA02840 is windblown sand; in PIA02840, this sand enhances the appearance of the layers.Note: In the context image above, the boxes marked A, B, and C refer to PIA02842 (this release), PIA02841 and (PIA02840) respectively.
Voir l'image PIA02842: Layered Material in West Arabia Terra Crater sur le site de la NASA.
On December 3rd, Mars Polar Lander and the Deep Space 2 Microprobes (Scott and Amundsen) will land somewhere in the picture shown here. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle camera view of the polar landing ellipse was taken on November 28, 1999. Dark patches within the ellipse are sand and small fields of windblown sand dunes. The bright patches toward the top of the image are frost. It is late spring in this portion of the martian south polar region, and much of the winter frost has finally sublimed away. The ellipse center is located at 76°S 195°W. In this view, nor this toward the bottom and sunlight illuminates the scene from the lower right. The image covers an area approximately 105 km (65 miles) wide by 335 km (210 miles) long.
Voir l'image PIA02348: Latest Color View of Polar Landing Site sur le site de la NASA.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Voir l'image PIA03169: Springtime on the Martian South Polar Cap sur le site de la NASA.
Figure caption from Science Magazine
Voir l'image PIA00814: Coprates Chasma sur le site de la NASA.
11 May 2004
This composite of 7.5 km (4.7 mi) per pixel daily global images, acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC), shows water ice clouds over and to the east (right) of the Mars Exploration Rover (MER-B), Opportunity, landing site in Meridiani Planum. The "+" indicates the location of the rover site. Clouds high in the atmosphere above the Opportunity site have been a common occurrence in the afternoon for the past several weeks. This picture was obtained on 1 May 2004. The scale bar, 120 km (~75 mi), is approximate. North is toward the top/upper right. The bright area to the west (left) of the landing site is sunlight glinting off particles in the atmosphere and on the ground. The sun illuminates the scene from the left.
This and other images of both MER landing sites are featured each week in the MGS weather reports, located online at: http://www.msss.com/mars_images/moc/mer_weather/.
This is a Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle view of the Charitum Montes, south of Argyre Planitia, in early June 2003. The seasonal south polar frost cap, composed of carbon dioxide, has been retreating southward through this area since spring began a month ago. The bright features toward the bottom of this picture are surfaces covered by frost. The picture is located near 57°S, 43°W. North is at the top, south is at the bottom. Sunlight illuminates the scene from the upper left. The area shown is about 217 km (135 miles) wide.
Voir l'image PIA04569: Frost in Charitum Montes sur le site de la NASA.
The white or bluish-white features are clouds. Clouds are common over the larger Tharsis volcanoes in mid-afternoon. The four largest volcanoes are more than 15 km (9 mi) high. Viewed from Earth by telescope before any spacecraft had visited the planet, astronomers often described a "W"-shaped white cloud over the Tharsis region. This "W" was actually the result of seeing the combined effects of bright clouds hanging over the Ascraeus, Pavonis, Arsia, and Olympus volcanoes. The clouds result when warm air containing water vapor rises up the slopes of each volcano, cools at the higher altitude, and causes the water vapor to freeze and form a cloud of ice crystals.
Pavonis Mons lies on the martian equator, north is up, and sunlight is illuminating the scene from the left. The picture is a mosaic of red and blue filter images taken on three consecutive orbits. The slightly blurred appearance of the left side of Arsia Mons results from distortion toward the edges of the images used to make the mosaic. To remove the blur, an image obtained on another day would be added to the mosaic--however, this image would not match well because the cloud patterns will have changed by the next day. Mosaics such as the one shown here are used to monitor changes in martian weather and to plan future observations.
Voir l'image PIA02049: Regional View of the Tharsis Volcanoes sur le site de la NASA.
Smile! Spring has sprung in the martian southern hemisphere. With it comes the annual retreat of the winter polar frost cap. This view of "Happy Face Crater"--officially named "Galle Crater"--shows patches of white water ice frost in and around the crater's south-facing slopes. Slopes that face south will retain frost longer than north-facing slopes because they do not receive as much sunlight in early spring. This picture is a composite of images taken by the Mars Global Surveyor Mars Orbiter Camera (MOC) red and blue wide angle cameras. The wide angle cameras were designed to monitor the changing weather, frost, and wind patterns on Mars. Galle Crater is located on the east rim of the Argyre Basin and is about 215 kilometers (134 miles) across. In this picture, illumination is from the upper left and north is up.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Voir l'image PIA02325: Have a Nice Spring! MOC Revisits "Happy Face" Crater sur le site de la NASA.
Annotated View of Arsia and Phobos
6 February 2006
This pair of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) color images shows early autumn clouds over the Arsia Mons volcano, plus the shadow of the innermost of the two martain moons, Phobos. The picture on the left is taken from the MOC daily global map acquired at 7.5 km (~4.7 mi) per pixel on 28 January 2006, about a week after the start of southern autumn. The picture on the right was taken at the same time, but at a higher resolution of 489 m (1604 ft) per pixel.
Both pictures are composites of MOC red and blue wide angle images, and both are oriented such that north is up and east is to the right. Arsia Mons and the other large Tharsis volcanoes commonly develop afternoon orographic (i.e., topographically-controlled) water ice clouds at this time of year. The equatorial Tharsis volcano, Pavonis Mons, is also under a deck of water ice clouds; it is located toward the upper right corner of the left, lower-resolution image.
Sunlight glints off the dusty surface and the clouds and aerosols in the atmosphere, producing the bright diagonal streak located just southeast (lower right) of Arsia Mons. A water ice haze is seen on the left side of the lower-resolution image. The dark oval to the northeast of Arsia Mons, as noted above, is the shadow of Phobos.
Location near: 9°S, 121°W
Image width: 100 km scale bar = ~62 mi; 300 km bar = ~186 mi
Illumination from: upper left
Season: Southern Autumn
This overview map made from Mars Orbiter camera images illustrates the path that the Mars Exploration Rover Spirit has taken from its first sol on the red planet through its 107th sol. As of sol 112 (April 26, 2004), Spirit has passed "Missoula" crater and sits approximately 1,900 meters (1.18 miles) away from its destination at the western base of the "Columbia Hills." While most of Spirit's journey has been over the very angular rocks that make up the ejecta fields surrounding "Bonneville" crater, the rover's next 50 or so sols will be spent traversing over martian plains that are dominated by rounder, vesicle-filled rocks.
Low-resolution Viking color images were used to "colorize" this frame. The process takes the red, green, and blue (RGB) low-resolution images and transforms them to hue (color), saturation (whether the colors are bold or pastel), and intensity (the brightness of the scene), or HSI. The high resolution grayscale image is then used to replace the low-resolution intensity image, and the images are transformed back to RGB. The colors were additionally modified to appear less saturated and more "Earth-like."
This image does not represent the "true" color of Mars
Voir l'image PIA01239: Coprates Catena sur le site de la NASA.
Although the resolution of the MOC wide angle cameras is too low to tell much about the geomorphology of the Cydonia region, the images from the red and blue wide angle cameras provide us with two types of information that is of interest in their own right: color and stereoscopic data. Above are a color view and a stereoscopic anaglyph rendition of Geodesy Campaign images acquired by MGS MOC in May 1999. To view the stereo image, you need red/blue "3-D" glasses.
Voir l'image PIA02381: Cydonia: Wide Angle Color Image sur le site de la NASA.
August 2, 1999, marks the spring equinox for the martian southern hemisphere. It is also the start of autumn for regions north of the equator. Winter in the south has finally come to a close, and the seasonal frosts of the wintertime south polar cap are retreating. Small, local dust storms frequently occur along the margins of the polar cap, as the colder air blowing off the cap moves northward into warmer regions.
The wide angle camera view of Mars shown here was obtained by the Mars Global Surveyor Mars Orbiter Camera in late July 1999, about 1 week before the start of southern spring. The frosty, retreating south polar cap (white) is seen in the lower quarter of the image, and wisps of dust storm clouds (grayish-orange in this view) occur just above the cap at the lower left. The southern most of the large environmental changes volcanoes, Arsia Mons, is seen at the upper left. Arsia Mons is about 350 kilometers(~220 miles) across.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Voir l'image PIA02096: Southern Mars: It's Spring! sur le site de la NASA.
This color-enhanced composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle images shows dust-raising events--small dust "storms" and a few very large dust devils--in the Syria/Claritas region around 2 p.m. (1400) local time on May 21, 2003. The region is southwest of the Labyrinthus Noctis, near 14°S, 108°W. Sunlight illuminates the scene from the left; winds were blowing from the west/southwest when the picture was taken.
This composite was constructed from a full-resolution (240 meters per pixel) red wide angle image and a much lower resolution (7.5 km per pixel) blue wide angle image acquired at the same time.
Voir l'image PIA04552: Syria/Claritas Dust Storm sur le site de la NASA.
12 September 2005
Mars Global Surveyor (MGS) entered Mars orbit on 12 September 1997.
Location near: 90°N
Season: Northern Summer
Elysium Mons was discovered by Mariner 9 in 1972. It differs in a number of ways from the familiar Olympus Mons and other large volcanoes in the Tharsis region. In particular, there are no obvious lava flows visible on the volcano's flanks. The lack of lava flows was apparent from the Mariner 9 images, but the new MOC high resolution image--obtained at 5.24 meters (17.2 feet) per pixel--illustrates that this is true even when viewed at higher spatial resolution.
Elysium Mons has many craters on its surface. Some of these probably formed by meteor impact, but many show no ejecta pattern characteristic of meteor impact. Some of the craters are aligned in linear patterns that are radial to the summit caldera--these most likely formed by collapse as lava was withdrawn from beneath the surface, rather than by meteor impact. Other craters may have formed by explosive volcanism. Evidence for explosive volcanism on Mars has been very difficult to identify from previous Mars spacecraft images. This and other MOC data are being examined closely to better understand the nature and origin of volcanic features on Mars.
The three MOC images, 40301 (red wide angle), 40302 (blue wide angle), and 40303 (high resolution, narrow angle) were obtained on Mars Global Surveyor's 403rd orbit around the planet around 9:58 - 10:05 p.m. PDT on July 2, 1998. The images were received and processed at Malin Space Science Systems (MSSS) around 4:00 p.m. PDT on July 4, 1998.
This image: Elysium Volcanic Region as seen by MOC on July 2, 1998. Volcano near top center is Hecates Tholus--note bright clouds off its northeast flank. Volcano near center is Elysium Mons; volcano toward lower right is Albor Tholus. Red channel is MOC red wide angle image 40301, the blue channel is MOC blue wide angle image 40302, and the green channel is synthesized by averaging the red and blue bands. Image is an orthographic projection centered at 24.85°N, 213.25°W. The scale at the center of the projection is 4.65 kilometers (2.9 miles) per pixel. North is up, illumination is from the lower right.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Voir l'image PIA01457: Elysium Mons Volcanic Region sur le site de la NASA.
Figure 1
Annotated Image
Figure 2
Narrow Angle Component
(non-stereo image)Figure 3
Narrow Angle Component
(non-stereo image)
24 January 2006
Two years ago, the Mars Exploration Rover, Opportunity, landed on Meridiani Planum. The rover marked its first Mars-year (687 Earth Days) anniversary in December 2005. Two pictures are shown here: the one on the right is the same as that on the left, except that key features have been labeled. Both pictures include a colored portion -- a 3-d (stereo) anaglyph which can be viewed using "3-d" glasses with a red left eye and a blue right eye. Figures 2 and 3 are MOC narrow angle non-stereo images.
During the landing in January 2004, rockets were fired to slow the final descent, just before the inflated airbags (containing the folded-up lander and rover) were released. The rockets disturbed the sandy surface at the location labeled "blast effects." Following release, the airbags bounced and rolled until coming to rest inside Eagle Crater. The lander, in fact, can be seen as a bright spot near the center of Eagle Crater. Meanwhile, the jettisoned parachute and backshell landed to the southwest of Eagle, and the heatshield fell just southwest of Endurance Crater.
Opportunity initially examined sedimentary rock outcrops and sandy, windblown regolith within Eagle Crater. Then it was driven by the rover team out of Eagle and on into Endurance Crater. By the end of 2004, Opportunity had left Endurance and was investigating the site where the heatshield impacted the surface. After that, the rover spent much of the year 2005 driving from the heatshield location down to the shallow Erebus Crater. Long-term plans call for driving Opportunity from Erebus to Victoria Crater, where a substantially thicker sequence of layered rock is expected to be found, relative to previous outcrops examined in the craters Endurance and Eagle.
Location near: 2.0°S, 5.6°W
Image width: 300 m scale bar = 984 ft
Illumination from: left
Every day, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle instruments obtain a global view of the planet to help monitor weather and seasonal patterns of frost deposition and removal. The two pictures shown here are taken from the same daily global image mosaic (the only difference is that each was processed slightly differently). The pictures show Galle Crater, informally known as "Happy Face," as it appeared in early southern winter. The white-ish gray surfaces are coated with wintertime carbon dioxide frost. The pattern of frost distribution gives the appearance that "Happy Face" has opened its mouth. Galle Crater is located on the east rim of Argyre at 51°S, 31°W. Sunlight illuminates the scene from the upper left. Galle Crater is 230 km (143 mi) across.
Voir l'image PIA04520: "Happy Face" Crater sur le site de la NASA.
Water is the chief agent of weathering and erosion on Earth. Mars is a much drier, colder planet on which liquid water cannot exist very long at the surface because it will immediately begin to boil, evaporate, and freeze--all at the same time. However, new pictures from the Mars Orbiter Camera (MOC) onboard the Mars Global Surveyor (MGS) have provided an astonishing observation which suggests that liquid water may have played a role in shaping some recent gully-like features found on the slopes of various craters, troughs, and other depressions on the red planet.
These pictures introduce the basic features of a martian gully. The figure on the left is an example from Mars, the figure on the right is a gully on Earth. In the Earth picture, rain water flowing under and seeping along the base of a recently-deposited volcanic ash layer has created the gully. For Mars, water is not actually seen but is inferred from the landforms and their similarity to examples on Earth.
The landforms both on Earth and Mars are divided into three parts: the alcove, the channel, and the apron. Water seeps from between layers of rock on the wall of a cliff, crater, or other type of depression. The alcove forms above the site of seepage as water comes out of the ground and undermines the material from which it is seeping. The erosion of material at the site of seepage causes rock and debris on the slope above this area to collapse and slide downhill, creating the alcove.
The channel forms from water and debris running down the slope from the seepage area. The point where the top of the channel meets the bottom of the alcove is, in many cases, the site where seepage is occurring. Channels are probably flushed-clean of debris from time to time by large flash floods of water released from behind an ice barrier that might form at the site of seepage during more quiescent times.
The aprons are the down-slope deposits of ice and debris that were moved down the slope and through the channel. Whether any water--likely in the form of ice--persists in these deposits is unknown. The fact that the aprons do not go very far out onto the floors of craters and troughs (e.g., the foreground of the figure on the left) indicates that there is a limit as to how much water actually makes it to the bottom of the slope in liquid form. Most of the water by the time it reaches the bottom of the slope has probably either evaporated or frozen.
The MOC image on the left was acquired July 3, 1999, and is located on the south-facing wall of an impact crater near 54.8°S, 342.5°W. The MOC image is illuminated from the upper left; north is toward the upper right. The MOC image covers an area 1.3 km (0.8 mi) wide by 2 km (1.2 mi) long. The pictures from the flank of the Mount St. Helens volcano in Washington (right; large image and inset) were taken by MGSMOC Principal Investigator, Michael C. Malin, in the 1980s after the eruptions of May 1980. They are illuminated from the left; note footprints on left side of the picture for scale, also note the colored bar, which is 30 cm (11.8 in) long.
Voir l'image PIA01031: Evidence for Recent Liquid Water on Mars: Basic Features of Martian Gullies sur le site de la NASA.
The Mars Picture of the Day for June 10, 2003, showed an early southern spring view of the frost-covered Charitum Montes, south of Argyre Planitia. Today's picture shows some of the same mountain range, as it appeared in early June 2003 when viewed the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle cameras. This perspective view was created by combining MOC red and blue camera images with topographic data from the Mars Orbiter Laser Altimeter (MOLA), another instrument onboard MGS. The bright areas are surfaces covered by frost. The picture is located near 57°S, 43°W. Sunlight illuminates the scene from the upper left. North, and Argyre Planitia, are toward the top.
Voir l'image PIA04606: Frosty Mountains sur le site de la NASA.
The martian northern plains remain nearly as mysterious today as they seemed 25 years ago during the Viking missions, even though one of those spacecraft--the Viking 2 lander--went to the northern plains. The northern plains are a lowland with fewer impact craters exposed at the surface than the heavily cratered martian southern highlands. Normally, surfaces with fewer craters are considered younger (i.e., they have had less time to accumulate craters). Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) high resolution images have shown that there really are a lot of craters in this region, but most are thinly buried beneath the plains. This low resolution view, covering an area 168 km (104 mi) by 124 km (77 km), shows a few craters at the surface (such as the one at the center of the image), and several circular features that represent craters that are mostly buried beneath the plains. This view was obtained in August 2002; sunlight illuminates the scene from the lower left.
Voir l'image PIA04053: The Martian Northern Plains sur le site de la NASA.
This mosaic of two Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images shows about 20 different gullies coming down the south-facing wall of a trough in the Sirenum Fossae/Gorgonum Chaos region of the martian southern hemisphere. Each channel and its associated fan--or apron--of debris appears to have started just below the same hard, resistant layer of bedrock located approximately 100 meters (about 325 feet) below the top of the trough wall. The layer beneath this hard, resistant bedrock is interpreted to be permeable, which allows ground water to percolate through it and--at the location of this trough--seep out onto the martian surface. The channels and aprons only occur on the south-facing slope of this valley created by faults on each side of the trough. The depression is approximately 1.4 km (0.9 mi) across.
The mosaic was constructed from two pictures taken on September 16, 1999, and May 1, 2000. The black line is a gap between the two images that was not covered by MOC. The scene covers an area approximately 5.5 kilometers (3.4 miles) wide by 4.9 km (3.0 mi) high. Sunlight illuminates the area from the upper left. The image is located near 38.5°S, 171.3°W. MOC high resolution images are taken black-and-white (grayscale); the color seen here has been synthesized from the colors of Mars observed by the MOC wide angle cameras and by the Viking Orbiters in the late 1970s.
Voir l'image PIA01040: Evidence for Recent Liquid Water on Mars: Gullies in Sirenum Fossae Trough sur le site de la NASA.
One of the primary objectives for the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) during the Extended Mission is to continue daily monitoring of martian weather as expressed in clouds, dust storms, and patches of polar frost. During the Primary Mission, which lasted from March 1999 through January 2001, changes that occurred over a single martian year (687 Earth days) were observed. Now it is possible to see what the martian atmosphere will do for at least two-thirds of a second martian year, because the Extended Mission will run into April 2002.
This picture captures two dust storms, each large enough to cover Arizona or New Mexico. One is located near the lower left, the other at the lower right. Taken on April 8, 2001 (mid-southern winter), this is a mosaic of six MOC daily global images centered around Hellas Planitia in the martian southern hemisphere. Hellas Planitia is the dominant elliptical feature just below the center of the picture. The bright, nearly white surfaces along the lower (southern) edge of the picture are covered by wintertime frost. The strong temperature difference between the winter frost and the warmer air just off the edge of this polar cap generates winds that--at this time of year--are often strong enough to lift dust into large, reddish-brown, billowy clouds.
North is up and sunlight illuminates the area from the upper left. The martian equator forms the arc along the top of the picture; 500 kilometers (km) is equal to about 311 miles. The approximately 500 kilometer-wide circular feature just above the center is the crater Huygens.
Voir l'image PIA03222: Mid-Winter Dust Storms Near Hellas Planitia sur le site de la NASA.
The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) opened its fourth year orbiting the red planet with this mid-autumn view of three major valley systems east of the Hellas plains. From left to right, the first major valley, Dao Vallis, runs diagonally from the upper left to just past the lower center of the image. Niger Vallis joins Dao Vallis just above the center of the frame. Harmakhis Vallis extends diagonally across the right half of the picture, toward the lower right. These valleys are believed by some to have been formed--at least in part--by large outbursts of liquid water some time far back in the martian past, though there is no way to know exactly how many hundreds of millions or billions of years ago this might have occurred. In each valley, water would have flowed toward the bottom of the image. Although their dimensions vary along their courses, the valleys are all roughly 1 km (0.6 miles) deep and range in width from about 40 km (25 miles) down to about 8 km (5 mi). Located around 40°S, 270°W, the picture covers an area approximately 800 km across and is illuminated by sunlight from the lower left. North is toward the left; the picture is a composite of red and blue wide angle images obtained by MOC on September 13, 2000.
Voir l'image PIA02810: Looking Out Across Dao, Niger, and Harmakhis Valles sur le site de la NASA.
One of the benefits of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) Extended Mission is the opportunity to observe how the planet's weather changes during a second full martian year. This picture of Arsia Mons was taken June 19, 2001; southern spring equinox occurred the same day. Arsia Mons is a volcano nearly large enough to cover the state of New Mexico. On this particular day (the first day of Spring), the MOC wide angle cameras documented an unusual spiral-shaped cloud within the 110 km (68 mi) diameter caldera--the summit crater--of the giant volcano. Because the cloud is bright both in the red and blue images acquired by the wide angle cameras, it probably consisted mostly of fine dust grains. The cloud's spin may have been induced by winds off the inner slopes of the volcano's caldera walls resulting from the temperature differences between the walls and the caldera floor, or by a vortex as winds blew up and over the caldera. Similar spiral clouds were seen inside the caldera for several days; we don't know if this was a single cloud that persisted throughout that time or one that regenerated each afternoon. Sunlight illuminates this scene from the left/upper left.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Voir l'image PIA03470: Arsia Mons Spiral Cloud sur le site de la NASA.
Gullies eroded into the wall of a meteor impact crater in Noachis Terra. This high resolution view (top left) from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) shows channels and associated aprons of debris that are interpreted to have formed by groundwater seepage, surface runoff, and debris flow. The lack of small craters superimposed on the channels and apron deposits indicates that these features are geologically young. It is possible that these gullies indicate that liquid water is present within the martian subsurface today.
The MOC image was acquired on September 28, 1999. The scene covers an area approximately 3 kilometers (1.9 miles) wide by 6.7 km (4.1 mi) high (note, the aspect ratio is 1.5 to 1.0). Sunlight illuminates this area from the upper left. The image is located near 54.8°S, 342.5°W. The context image (above) shows the location of the MOC image on the south-facing wall of an impact crater approximately 20 kilometers (12 miles) in diameter. The context picture was obtained by the Viking 1 orbiter in 1980 and is illuminated from the upper left. The large mound on the floor of the crater in the context view is a sand dune field. The Mars Orbiter Camera high resolution images are taken black-and-white (grayscale); the color seen here has been synthesized from the colors of Mars observed by the MOC wide angle cameras and by the Viking Orbiters in the late 1970s.
A brief description of how the color was generated:The MOC narrow angle camera only takes grayscale (black and white) pictures. To create the color versions seen here, we have taken much lower resolution red and blue images acquired by the MOC's wide angle cameras, and by the Viking Orbiter cameras in the 1970s, synthesized a green image by averaging red and blue, and created a pallette of colors that represent the range of colors on Mars. We then use a relationship that correlates color and brightness to assign a color to each gray level. This only a crude approximation of martian color and should only be considered representative of Mars. It is likely Mars would not look like this to a human observer at Mars.
Voir l'image PIA01035: Evidence for Recent Liquid Water on Mars: Gullies in Crater Wall, Noachis Terra sur le site de la NASA.
Autumn on the martian northern plains means clouds and dust storms. As autumn got underway in early May 2003, large dust storms began to form on the northern plains and sweep their way eastward--and sometimes southward--bringing colder air down from the north polar cap, now shrouded in darkness and clouds. This early autumn view, assembled from Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images, shows an eastward-moving dust storm on the plains north of Cydonia and western Arabia Terra. The storm is nearly as big as the continental United States are wide, from west to east. In this image, north is toward the top, east to the right, and sunlight illuminates the scene from the lower left.
Voir l'image PIA04598: Autumn Dust Storm sur le site de la NASA.
The story of the Mars Orbiter Camera (MOC) onboard the Mars Global Surveyor(MGS) spacecraft began with a proposal to NASA in 1985. The first MOC flew on Mars Observer, a spacecraft that was lost before it reached the red planet in 1993. Now, after 14 years of effort, a MOC has finally been placed in the desired mapping orbit. The MOC team's happiness is perhaps best expressed by the planet Mars itself. On the first day of the Mapping Phase of the MGS mission--during the second week of March 1999--MOC was greeted with this view of "Happy Face Crater" (center right) smiling back at the camera from its location on the east side of Argyre Planitia. This crater is officially known as Galle Crater, and it is about 215 kilometers (134 miles) across. The picture was taken by the MOC's red and blue wide angle cameras. The bluish-white tone is caused by wintertime frost. Illumination is from the upper left. For more information and Viking Orbiter views of "Happy Face Crater," see http://www.msss.com/education/happy_face/happy_face.html.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
The four still-frame images (above) show the evolution of a storm system that developed over the martian north polar region on June 30, 1999. Each picture was taken approximately 2 hours later than the previous. The north polar ice cap is the white feature at the center of each frame. Clouds that appear white consist mainly of water ice, clouds that appear orange/brown contain dust.
This particular storm system lasted well into the next day--July 1, 1999. A total of 23 red and 23 blue camera images were used to create a time-lapsed "movie" that displays the development and evolution of this storm over the two-day period. Of great interest are the "curling" of the clouds behind the largest of the storms--this indicates a flow vortex that follows the storm front that is moving toward the top/upper right of the frame--and the correlation of white water-ice clouds with orange/brown dust clouds. High surface winds must have raised dust and mixed it with water vapor in the air over the summer-time polar cap to create this effect. To view the "movie," click or download to your desktop the following 2.2 MByte MPG file.
Storms similar to those shown here were observed to continue throughout the month of July and into August. Over the next several months, the north polar cap will grow dark as the region transitions through autumn and into winter. When northern winter begins in December 1999, this region will be dark and obscured by clouds.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Voir l'image PIA02305: Late Summer Storms Over the Mars North Polar Region sur le site de la NASA.
MOC wide angle cameras captured a dust storm advancing across the northern plains toward Tempe Terra on August 22, 1998.
Northern Acidalia Planitia was engulfed in a continent-sized dust storm in mid-May 2003. This composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images shows the early autumn dust storm (top 1/4 of the picture) sweeping east-northeast (toward upper right) across the northern plains. Dust storms like these are common in early autumn and generally last about a day or two.
This simple cylindrical view of Mars covers regions from eastern Kasei Valles/northeast Tempe Terra (in the upper left), to central Arabia Terra (center right), Argyre Basin (lower left), Noachis Terra (lower right), and the northern edge of the retreating south polar seasonal frost cap (bottom). Sunlight illuminates the scene from the left.
Voir l'image PIA04547: May Dust Storm in Acidalia sur le site de la NASA.
Hundreds of layers of similar thickness, texture, and pattern have been exposed by erosion in a 64 kilometer-wide (40 mile-wide) impact crater in western Arabia Terra at 8°N, 7°W. In other words, these layers provide a record of repeated, episodic changes that took place at some time far in the martian past, when this particular impact crater was the site of sediment deposition. Layers toward the center of the crater are nearly horizontal, but those closer to or draping over the crater walls are tilted (geologist use the term dipping) toward the basin center. These relationships suggest that the sediments that created these layers were deposited from above--perhaps by settling out of the martian atmosphere, or perhaps by settling out of water that might have occupied this crater as a lake.
The context view (above) was taken by the Viking 1 orbiter in 1978; in it, north is up and sunlight illuminates the scene from the right. The three Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) narrow angle (high resolution) views (PIA02840, PIA02841 (this release), PIA02842) sample layer outcrops that were previously not known to exist in this crater. Each MOC image is illuminated from the left. Dark material in PIA02841 (this release) and PIA02840 is windblown sand; in PIA02840, this sand enhances the appearance of the layers.Note: In the context image above, the boxes marked A, B, and C refer to PIA02842, PIA02841 (this release), and (PIA02840 respectively.
Voir l'image PIA02841: Layered Material in West Arabia Terra Crater sur le site de la NASA.
It is still winter in the northern hemisphere of Mars. On April 20, 2000, the Mars Orbiter Camera (MOC) onboard Mars Global Surveyor (MGS) captured this view of a chilly Lomonosov Crater. The rims of the crater appear white because they are covered with wintertime frost. A dark patch just right of center on the crater floor is a sand dune field. Both low-lying ground fogs(fuzzy, patchy areas around the lower perimeter of the crater) and higher cloud layers (fuzzy white arcs seen within the crater and towards the upper right) obscure much of the surface. The sun, only 12° above the horizon, bathes the scene in a reddish-brown hue. Lomonosov Crater is about 150 km (93 mi) across and located on the martian northern plains at 64.8° N, 8.8° W. The crater is named for the 18th Century Russian chemist, Mikhail V. Lomonosov (1741-1765). Spring will arrive in the martian northern hemisphere around June 1, 2000, and summer will come in December 2000. Sunlight illuminates this scene from the lower left.
Voir l'image PIA02394: The Frosty Rims of Lomonosov Crater in Winter sur le site de la NASA.
During the last week of September and the first week or so of October 2006, scientific instruments on NASA's Mars Reconnaissance Orbiter were turned on to acquire test information during the transition phase leading up to full science operations. The mission's primary science phase will begin the first week of November 2006, following superior conjunction. (Superior conjunction is where a planet goes behind the sun as viewed from Earth.) Since it is very difficult to communicate with a spacecraft when it is close to the sun as seen from Earth, this checkout of the instruments was crucial to being ready for the primary science phase of the mission.
Throughout the transition-phase testing, the Mars Color Imager (MARCI) acquired terminator (transition between nighttime and daytime) to terminator swaths of color images on every dayside orbit, as the spacecraft moved northward in its orbit. The south polar region was deep in winter shadow, but the north polar region was illuminated the entire Martian day. During the primary mission, such swaths will be assembled into global maps that portray the state of the Martian atmosphere -- its weather -- as seen every day and at every place at about 3 p.m. local solar time. After the transition phase completed, most of the instruments were turned off, but the Mars Climate Sounder and MARCI have been left on. Their data will be recorded and played back to Earth following the communications blackout associated with conjunction.
Combined with wide-angle image mosaics taken by the Mars Orbiter Camera on NASA's Mars Global Surveyor at 2 p.m. local solar time, the MARCI maps will be used to track motions of clouds.
This image is a composite mosaic of four polar views of Mars, taken at midnight, 6 a.m., noon, and 6 p.m. local Martian time. This is possible because during summer the sun is always shining in the polar region. It shows the mostly water-ice perennial cap (white area), sitting atop the north polar layered materials (light tan immediately adjacent to the ice), and the dark circumpolar dunes. This view shows the region poleward of about 72 degrees north latitude. The data were acquired at about 900 meters (about 3,000 feet) per pixel. Three channels are shown here, centered on wavelengths of 425 nanometers, 550 nanometers and 600 nanometers.
The shadow of the martian moon, Phobos, has been captured in many recent wide angle camera views of the red planet obtained by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC). Designed to monitor changes in weather and surface conditions, the wide angle cameras are also proving to be a good way to spot the frequent solar eclipses caused by the passage of Phobos between Mars and the Sun.
The first figure (above), shows wide angle red (left), blue (middle), and color composite (right) views of the shadow of Phobos (elliptical feature at center of each frame) as it was cast upon western Xanthe Terra on August 26, 1999, at about 2 p.m.local time on Mars. The image covers an area about 250 kilometers (155 miles) across and is illuminated from the left. The meandering Nanedi Valles is visible in the lower right corner of the scene. Note the dark spots on three crater floors--these appear dark in the red camera image (left) but are barely distinguished in the blue image (middle), while the shadow is dark in both images. The spots on the crater floors are probably small fields of dark sand dunes.
The second figure shows three samples of MOC's global image swaths, each in this case with a shadow of Phobos visible (arrow). The first scene (left) was taken on September 1, 1999, and shows the shadow of Phobos cast upon southern Elysium Planitia. The large crater with dark markings on its floor at the lower right corner is Herschel Basin. The second scene shows the shadow of Phobos cast upon northern Lunae Planum on September 8, 1999. Kasei Valles dominates the upper right and the deep chasms of Valles Marineris dominate the lower third of the September 8 image. The picture on the right shows the shadow of Phobos near the giant volcano, Olympus Mons (upper left), on September 25, 1999. Three other major volcanoes are visible from lower-center (Arsia Mons) and right-center (Pavonis Mons) to upper-middle-right (Ascraeus Mons).
Phobos and the smaller, more distant satellite, Deimos, were discovered in 1877 by Asaph Hall, an astronomer at the United States Naval Observatory in Washington, D.C. Hall had been hunting for martian satellites for some time, and was about to abandon the search when he was encouraged by his wife to continue. In honor of her role, the largest crater on Phobos was named Stickney, her maiden name. Phobos is a tiny, potato-shaped world that is only about 13 km by 11 km by 9 km (8 mi by 7 mi by 6 mi) in size.
In 1912 Edgar Rice Burroughs published a story entitled "Under the Moons of Mars" (printed in book form in 1917 as A Princess of Mars) in which he referred to the "hurtling moons of Barsoom" (Barsoom being the "native" word for Mars in the fictional account). Burroughs was inspired by the fact that Phobos, having an orbital period of slightly less than 8 hours, would appear from Mars to rise in the west and set in the east only five and a half hours later. (Despite Burroughs' phrase, the outer moon, Deimos, can hardly be said to "hurtle" -- it takes nearly 60 hours to cross the sky from east to west, rising on one day and not setting again for over two more.)
If you could stand on Mars and watch Phobos passing overhead, you would notice that this moon appears to be only about half the size of what Earth's Moon looks like when viewed from the ground. In addition, the Sun would seem to have shrunk to about 2/3 (or nearly 1/2) of its size as seen from Earth. Martian eclipses are therefore dark but not as spectacular as total solar eclipses on Earth can be. In compensation, the martian eclipses are thousands of times more common, occurring a few times a day somewhere on Mars whenever Phobos passes over the planet's sunlit side. Due to the changing geometry of the MGS orbit relative to that of Phobos, the shadow is actually seen in MOC global map images (like in the second figure above) about a dozen times a month.
The shadow of Phobos was seen during the Viking missions in the late 1970s, and in fact one day the shadow was observed to pass right over the Viking 1 lander. The surface of Phobos itself was first imaged by Mariner 9 in 1971, and global coverage was obtained by the Viking orbiters in 1976-80. Phobos was the target of the ill-fated Phobos 1 and Phobos 2 spacecraft, launched by the Soviet Union in 1988. Phobos 2 actually reached Mars in 1989 and obtained a few pictures of the satellite--it also captured the shadow of Phobos cast upon the martian surface using its thermal infrared imager, Termoskan. More recently, the MGS MOC observed the tiny moon four times in August and September 1998.
Voir l'image PIA02342: MOC Views of Martian Solar Eclipses sur le site de la NASA.
This is the south polar cap of Mars as it appeared to the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) on April 17, 2000. In winter and early spring, this entire scene would be covered by frost. In summer, the cap shrinks to its minimum size, as shown here. Even though it is summer, observations made by the Viking orbiters in the 1970s showed that the south polar cap remains cold enough that the polar frost (seen here as white) consists of carbon dioxide. Carbon dioxide freezes at temperatures around -125° C (-193° F). Mid-summer afternoon sunlight illuminates this scene from the upper left from about 11.2° above the horizon. Soon the cap will experience sunsets; by June 2000, this pole will be in autumn, and the area covered by frost will begin to grow. Winter will return to the south polar region in December 2000. The polar cap from left to right is about 420 km (260 mi) across.
Voir l'image PIA02393: South Polar Cap, Summer 2000 sur le site de la NASA.
While many of the layered outcrops in craters and chasms on Mars are seen as stair-stepped series of cliffs and benches composed of similar materials with similar thicknesses, other layer outcrops are expressed on relatively smooth, rounded slopes as alternating light and dark bands. The best example of this variety of layered sedimentary material is found in southern Holden Crater. Holden is located at 26.5°S, 33.9°W, and has a diameter of 141 km (88 mi). The context picture above, shows that a valley, Uzboi Vallis, enters the crater on its southwestern side. Not too far from where Uzboi Vallis meets Holden Crater, rounded slopes and buttes consisting of alternating light and dark bands are seen. The origin of these layers is not known, but like those found in other craters on Mars, they might have resulted from deposition of sediment in a lake that would have occupied Holden Crater. Alternatively, these are materials deposited by falling out of the air, the same way that volcanic ash is deposited on Earth. The Viking mosaic (above) images are illuminated by sunlight from the upper right. The MOC image (top left) is illuminated from the upper left. North is up.
Voir l'image PIA02846: Sediment History Preserved in Gale Crater Central Mound sur le site de la NASA.
As the Mars Global Surveyor Primary Mission draws to an end, the southern hemisphere of Mars is in the depths of winter. At high latitudes, it is dark most, if not all, of the day. Even at middle latitudes, the sun shines only thinly through a veil of water and carbon dioxide ice clouds, and the ground is so cold that carbon dioxide frosts have formed. Kaiser Crater (47°S, 340°W) is one such place. At a latitude comparable to Seattle, Washington, Duluth, Minnesota, or Helena, Montana, Kaiser Crater is studied primarily because of the sand dune field found within the confines of its walls (lower center of the Mars Orbiter Camera image, above). The normally dark-gray or blue-black sand can be seen in this image to be shaded with light-toned frost. Other parts of the crater are also frosted. Kaiser Crater and its dunes were the subject of an earlier presentation of results. Close-up pictures of these and other dunes in the region show details of their snow-cover, including small avalanches. The two Mars Global Surveyor Mars Orbiter Camera images that comprise this color view (M23-01751 and M23-01752) were acquired on January 26, 2001.
Voir l'image PIA03206: Winter Frosted Dunes in Kaiser Crater sur le site de la NASA.
The Mars Global Surveyor Mars Orbiter Camera (MOC) wide angle system is used to monitor changes in martian weather and the seasonal coming and going of polar frost. These four wide angle pictures of craters in both the northern and southern middle and polar latitudes of Mars show examples of frost monitoring conducted by the MOC in recent months. It is spring in the northern hemisphere, and frost that accumulated during the most recent 6-month-long winter has been retreating since May. Examples of frost-rimmed craters include Lomonosov (top, left) and an unnamed crater farther north (top, right). The unnamed crater has a patch of frost on its floor that--based on how it looked during the 1970s Viking missions--is expected to persist through summer. It is autumn in the southern hemisphere, and frost was seen as early as August in some craters, such as Barnard (bottom, left); later the frost line moved farther north, and we began to see frost in Lowell Crater (bottom, right) in mid-October. For a view of what Lomonosov Crater looked like during northern winter, see "The Frosty Rims of Lomonosov Crater in Winter."
This is a series of 4 images. Each image is a composite of two pictures obtained at the same time, a red wide angle view and a blue wide angle view. In each picture, north is toward the top and sunlight illuminates the scene from the upper left (for southern hemisphere) or lower left (for northern hemisphere).
Voir l'image PIA02834: The Frosted Craters of Northern Spring and Southern Autumn - Unnamed Crater sur le site de la NASA.
Stretching along "Low Ridge" in front of the winter haven for NASA's Mars Exploration Rover Spirit are several continuous rock layers that make up the ridge. Some of these layers form fins that stick out from the other rocks in a way that suggests that they are resistant to erosion. Spirit is currently straddling one of these fin-like layers and can reach a small bit of light-toned material that might be a broken bit of it. Informally named "Halley," this rock was broken by Spirit's wheels when the rover drove over it.
The first analyses of Halley showed it to be unusual in composition, containing a lot of the minor element zinc relative to the soil around it and having much of its iron tied up in the mineral hematite. When scientists again placed the scientific instruments on Spirit's robotic arm on a particularly bright-looking part of Halley, they found that the chemical composition of the bright spots was suggestive of a calcium sulfate mineral. Bright soils that Spirit has examined earlier in the mission contain iron sulfate.
This discovery raises new questions for the science team: Why is the sulfate mineralogy here different? Did Halley and the fin material form by water percolating through the layered rocks of Low Ridge? When did the chemical alteration of this rock occur? Spirit will continue to work on Halley and other light-toned materials along Low Ridge in the coming months to try to answer these questions.
Spirit took this red-green-blue composite image with the panoramic camera on the rover's 820th sol, or Martian day, of exploring Mars (April 24, 2006). The image is presented in false color to emphasize differences among materials in the rocks and soil. It combines frames taken through the camera's 750-nanometer, 530-nanometer, and 430-nanometer filters. The middle of the imaged area has dark basaltic sand. Spirit's wheel track is at the left edge of the frame. Just to the right of the wheel track in the lower left are two types of brighter material examined by Spirit at the Halley target. The bluer material yielded the evidence for a calcium sulfate mineral.
Arsia Mons (above) is one of the largest volcanoes known. This shield volcano is part of an aligned trio known as the Tharsis Montes--the others are Pavonis Mons and Ascraeus Mons. Arsia Mons is rivaled only by Olympus Mons in terms of its volume. The summit of Arsia Mons is more than 9 kilometers (5.6 miles) higher than the surrounding plains. The crater--or caldera--at the volcano summit is approximately 110 km (68 mi) across. This view of Arsia Mons was taken by the red and blue wide angle cameras of the Mars Global Surveyor Mars Orbiter Camera (MOC) system. Bright water ice clouds (the whitish/bluish wisps) hang above the volcano--a common sight every martian afternoon in this region. Arsia Mons is located at 120° west longitude and 9° south latitude. Illumination is from the left.
Voir l'image PIA02337: Wide Angle View of Arsia Mons Volcano sur le site de la NASA.
The Mars Global Surveyor Mars Orbiter Camera (MOC) wide angle system is used to monitor changes in martian weather and the seasonal coming and going of polar frost. These four wide angle pictures of craters in both the northern and southern middle and polar latitudes of Mars show examples of frost monitoring conducted by the MOC in recent months. It is spring in the northern hemisphere, and frost that accumulated during the most recent 6-month-long winter has been retreating since May. Examples of frost-rimmed craters include Lomonosov (top, left) and an unnamed crater farther north (top, right). The unnamed crater has a patch of frost on its floor that--based on how it looked during the 1970s Viking missions--is expected to persist through summer. It is autumn in the southern hemisphere, and frost was seen as early as August in some craters, such as Barnard (bottom, left); later the frost line moved farther north, and we began to see frost in Lowell Crater (bottom, right) in mid-October. For a view of what Lomonosov Crater looked like during northern winter, see "The Frosty Rims of Lomonosov Crater in Winter."
This is a series of 4 images. Each image is a composite of two pictures obtained at the same time, a red wide angle view and a blue wide angle view. In each picture, north is toward the top and sunlight illuminates the scene from the upper left (for southern hemisphere) or lower left (for northern hemisphere).
Voir l'image PIA02833: The Frosted Craters of Northern Spring and Southern Autumn - Lomonosov Crater sur le site de la NASA.
During its March 1999 operations, the Mars Orbiter Camera (MOC) on board the Mars Global Surveyor (MGS) captured this stunning wide-angle camera view of the western portions of Melas and Candor Chasms in the Valles Marineris canyon system. This view covers an area that is about 80 kilometers (50 miles) wide and 220 kilometers (137 miles) long. Melas Chasma is located at the bottom of the image, Candor at the top. Hints of layers in the canyon walls are evident in this image. Color and albedo (brightness)variations on the floors of each chasm indicate the relative distribution of dark sand and brighter sediments and/or rocks. Dark sand on the floor of Melas Chasma was also seen by MOC in March 1999 (see MOC2-104) and bright layered material was observed in Candor Chasma in April 1998 (see MOC2-59).
The colors shown here are not true colors as they would appear to the human eye. The MOC has cameras that obtain images in red and blue portions of the visible spectrum; the green portion is synthesized using the combined average values of the red and blue channels (a relationship understood from Viking Orbiter imaging in the 1970s). Illumination is from the upper left.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Voir l'image PIA01692: Western Melas and Candor Chasms, Valles Marineris sur le site de la NASA.
This image is extracted from the global view shown in Slide #1. It features the Tharsis volcanoes (mostly covered by bluish-white water ice clouds) and the Valles Marineris trough system (to the right). This is a mosaic of global color images obtained on a single martian day in April 1999.
Voir l'image PIA02079: Tharsis and Marineris sur le site de la NASA.
Annotated image ofTharsis Limb Cloud
7 September 2005
This composite of red and blue Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired on 6 July 2005 shows an isolated water ice cloud extending more than 30 kilometers (more than 18 miles) above the martian surface. Clouds such as this are common in late spring over the terrain located southwest of the Arsia Mons volcano. Arsia Mons is the dark, oval feature near the limb, just to the left of the "T" in the "Tharsis Montes" label. The dark, nearly circular feature above the "S" in "Tharsis" is the volcano, Pavonis Mons, and the other dark circular feature, above and to the right of "s" in "Montes," is Ascraeus Mons. Illumination is from the left/lower left.
Season: Northern Autumn/Southern Spring
The first two pictures (top and above left) are from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) and show a series of troughs and layered mesas in the Gorgonum Chaos region of the martian southern hemisphere. The picture at the top of the page is a portion of the picture on the left above. The Viking view (above right) shows the location of the MOC image in the chaotic terrain. Gullies proposed to have been formed by seeping groundwater emanate from a specific layer near the tops of trough walls, particularly on south-facing slopes (south is toward the bottom of each picture). The presence of so many gullies associated with the same layer in each mesa suggests that this layer is particularly effective in storing and conducting water. Such a layer is called an aquifer, and this one appears to be present less than a few hundred meters (few hundred yards) beneath the surface in this region.
The MOC pictures were taken on January 22, 2000. The sample at the top of the page is an area 3 kilometers (1.9 miles) wide by 2.6 km (1.6 mi) high. The long view (above left) covers an area 3 kilometers (1.9 miles) wide by 22.6 km (14 mi) long. Sunlight illuminates each scene from the upper left. The images are located near 37.5°S, 170.5°W. The context image (above right) was acquired by the Viking 1 orbiter in 1977 and is illuminated from the upper right, north is up. MOC high resolution images are taken black-and-white (grayscale); the color seen here has been synthesized from the colors of Mars observed by the MOC wide angle cameras and by the Viking Orbiters in the late 1970s.
NOTE: A Full Resolution Grayscale view of the release image can be found here.
Voir l'image PIA01033: Evidence for Recent Liquid Water on Mars: Gullies in Gorgonum Chaos sur le site de la NASA.
Click on image for larger annotated version
7 January 2004
When the Mars Exploration Rover (MER-A), Spirit, was landing on 4 January 2004 (3 January 2004, PST), Mars Global Surveyor (MGS) was in position above the region to receive the critical entry, descent, and landing data via ultra high frequency (UHF) radio transmission to the MGS Mars Relay (MR) system. Data from the MR antenna are stored in the Mars Orbiter Camera (MOC) computer until they are transmitted to Earth. The transmission from Spirit on 4 January 2004 occurred in real time, as the rover descended, bounced, and rolled to a stop.
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the dark, wind-streaked plains of eastern Cerberus, located southeast of the Elysium volcanoes. The dark, diagonal lines are the Cerberus Fossae, a series of cracks where the surface of Mars has literally split open. This composite of red and blue MOC wide angle images was obtained in June 2003. The center of this view is located at 12.5°N, 201°W. North is up, east is to the right, and sunlight illuminates the scene from the lower left.
Voir l'image PIA04640: Eastern Cerberus sur le site de la NASA.
This image highlights the beginning--the Columbia Memorial Station--and possible end - the "Columbia Hills" - of the Mars Exploration Rover Spirit's journey. The image was taken by the camera on NASA's Mars Global Surveyor orbiter.
Mars Global Surveyor's (MGS) Mars Orbiter Camera (MOC) captured this view of a dust storm within the Ius and Melas Chasms of the Valles Marineris trough system on May 16, 1999.
The dust storm is seen in the lower 1/3 of the image. It occurs at the junction between eastern Ius Chasma and western Melas Chasma. The apparent motion of the storm is approximately from the south (bottom of image) toward the north. The dust cloud forms a sharp front along its northern margin, which is seen along the north wall of Ius and Melas Chasms--in fact, at the time the image was taken, the dust had advanced up over the north wall of Melas Chasma (upper portion of lower right third of image) and was advancing across the upland that separates this chasm from western Candor Chasma. For a clear-atmosphere view of western Candor and Melas Chasms, see "Western Melas and Candor Chasms, Valles Marineris, MOC2-105, 25 March 1999".
For scale, note that the large crater south of Hebes Chasma, Perrotin, is about 95 kilometers (59 miles) across. Bluish-white clouds in the image are interpreted to consist of water ice. The pink/red clouds of the dust storm occur closer to the ground, at a lower altitude than the water ice clouds.
One of the most interesting aspects of this dust storm is that Valles Marineris was observed to have a dust storm at exactly the same time of year, one Martian year ago. During its approach to Mars, MOC obtained a picture of the planet on July 2,1997, just prior to the Mars Pathfinder landing. At the time, it was winter in the southern hemisphere, and dust clouds were observed within Valles Marineris. The picture is seen in "Mars Orbiter Camera Views Mars Pathfinder Landing Site,MOC2-1, 3 July 1997". It will be interesting to see if similar storms occur within the Valles Marineris 1 and 2 Mars years hence. The next times will be in early April 2001 and mid-February 2003.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Newton Crater is a large basin formed by an asteroid impact that probably occurred more than 3 billion years ago. It is approximately 287 kilometers (178 miles) across. The picture shown here (top) highlights the north wall of a specific, smaller crater located in the southwestern quarter of Newton Crater (above). The crater of interest was also formed by an impact; it is about 7 km (4.4 mi) across, which is about 7 times bigger than the famous Meteor Crater in northern Arizona in North America.
The north wall of the small crater has many narrow gullies eroded into it. These are hypothesized to have been formed by flowing water and debris flows. Debris transported with the water created lobed and finger-like deposits at the base of the crater wall where it intersects the floor (bottom center top image). Many of the finger-like deposits have small channels indicating that a liquid--most likely water--flowed in these areas. Hundreds of individual water and debris flow events might have occurred to create the scene shown here. Each outburst of water from higher upon the crater slopes would have constituted a competition between evaporation, freezing, and gravity.
The individual deposits at the ends of channels in this MOC image mosaic were used to get a rough estimate of the minimum amount of water that might be involved in each flow event. This is done first by assuming that the deposits are like debris flows on Earth. In a debris flow, no less than about 10% (and no more than 30%) of their volume is water. Second, the volume of an apron deposit is estimated by measuring the area covered in the MOC image and multiplying it by a conservative estimate of thickness, 2 meters (6.5 feet). For a flow containing only 10% water, these estimates conservatively suggest that about 2.5 million liters (660,000 gallons) of water are involved in each event; this is enough to fill about 7 community-sized swimming pools or enough to supply 20 people with their water needs for a year.
The MOC high resolution view is located near 41.1°S, 159.8°W and is a mosaic of three different pictures acquired between January and May 2000. The MOC scene is illuminated from the left; north is up. The context picture was acquired in 1977 by the Viking 1 orbiter and is illuminated from the upper right.
Note: This is an updated color version of PIA01039.
Voir l'image PIA02824: Evidence for Recent Liquid Water on Mars: Channeled Aprons in a Small Crater within Newton Crater sur le site de la NASA.
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image covers an 800 by 300 km (500 by 190 mi) area located deep within the boundary of the seasonal south polar frost cap of Mars. Centered at 70°S, 320°W, this view--taken in early spring when sunlight has just begun to shine on the region for the first time in many months--includes a bright region (diagonal from center-left to lower right) known for nearly two centuries as the "Mountains of Mitchel." This feature was named for Ormsby McKnight Mitchel (1809-1862), an astronomer at the University of Cincinnati, Ohio, who discovered it while observing Mars through a telescope in 1846. Mitchel noticed that this area is typically "left behind" as a bright peninsula when the rest of the polarcap recedes past this area later in the spring.
Mitchel deduced that this area might be mountainous because it seemed analogous to the snow that is left on Earth's mountain ranges in late spring and into summer. Snow can remain on high peaks because the air temperature decreases with elevation (or altitude). MGS Mars Orbiter Laser Altimeter (MOLA) observations of this region show the bright "Mountains of Mitchel" to be a somewhat elevated region of rough, heavily cratered southern highlands. However, the "Mountains of Mitchel" do not appear to be mountains-there are other areas nearby at similar elevation that do not retain frost well into southern spring. Part of the Mountains of Mitchel feature includes a prominent, south-facing scarp (at center-left) that would tend to retain frost longer in the spring because it is somewhat protected from sunlight (which comes from the north). The persistence of frost on the Mountains of Mitchel remains mysterious, but new observations from the MGS MOC are helping to unravel the story. Thus far, it seems that the frost here--for whatever reason--tends to be brighter than frost in most other places within the polar cap. This brighter frost reflects sunlight and thus sublimes more slowly than adjacent, darker frost surfaces.
This color picture was compiled from MOC red and blue wide angle images. North is up and sunlight illuminates the scene from the upper left. The surface does not appear to be white--as might be expected for frost--because of dust both on the surface and in the atmosphere, as well dark sand that was being exposed from beneath the retreating frost at the time that the picture was taken.
Voir l'image PIA02336: The Mysterious Martian Mountains of Mitchel sur le site de la NASA.
The Mars Global Surveyor Mars Orbiter Camera (MOC) wide angle system is used to monitor changes in martian weather and the seasonal coming and going of polar frost. These four wide angle pictures of craters in both the northern and southern middle and polar latitudes of Mars show examples of frost monitoring conducted by the MOC in recent months. It is spring in the northern hemisphere, and frost that accumulated during the most recent 6-month-long winter has been retreating since May. Examples of frost-rimmed craters include Lomonosov (top, left) and an unnamed crater farther north (top, right). The unnamed crater has a patch of frost on its floor that--based on how it looked during the 1970s Viking missions--is expected to persist through summer. It is autumn in the southern hemisphere, and frost was seen as early as August in some craters, such as Barnard (bottom, left); later the frost line moved farther north, and we began to see frost in Lowell Crater (bottom, right) in mid-October. For a view of what Lomonosov Crater looked like during northern winter, see "The Frosty Rims of Lomonosov Crater in Winter."
This is a series of 4 images. Each image is a composite of two pictures obtained at the same time, a red wide angle view and a blue wide angle view. In each picture, north is toward the top and sunlight illuminates the scene from the upper left (for southern hemisphere) or lower left (for northern hemisphere).
Voir l'image PIA02835: The Frosted Craters of Northern Spring and Southern Autumn - Barnard Crater sur le site de la NASA.
The Mars Orbiter Camera (MOC) obtained this spectacular wide-angle view of Olympus Mons on Mars Global Surveyor's 263rd orbit, around 10:40 p.m. PDT on April 25, 1998. In the view presented here, north is to the left and east is up. The spacecraft was traveling from north to south (left to right). Although the camera looks straight down (towards the nadir) and cannot be pointed to the side, the wide angle camera has such a large field of view (it sees from horizon to horizon) that, in effect, it provides side looking views. Unlike some other MOC images, that have had to be warped to provide a view as if seen from a certain direction and altitude, this image shows what the camera saw without additional processing. It is easy to imagine that you are looking out a window at the surface of Mars from about 900 km (560 miles) up.
The image was taken on a cool, crisp winter morning. The west side of the volcano (lower portion of view, above) was clear and details on the surface appear very sharp. The skies above the plains to the east of Olympus Mons (upper portion of view) were cloudy. Clouds were lapping against the lower east flanks of this 26 kilometers (16 miles) high volcano, but the summit skies were clear.
When Mars Global Surveyor attains its Mapping Orbit in March 1999, the MOC wide angle camera system will be used to make daily, global maps of martian clouds and weather systems. The wide angle images will resemble weather satellite pictures of Earth, and will help the Mars science teams plan their observations and test computer-driven Mars weather prediction models.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Voir l'image PIA01476: Olympus Mons, 1998 (color) sur le site de la NASA.
In the image above, north is to the top. The camera is viewing towards the west. The image is the composite of MOC frames P013_01 and P013_02. Because the MOC acquires its images one line at a time, the cant angle towards the sun-lit portion of the planet, the spacecraft orbital velocity, and the spacecraft rotational velocity combine to distort the image slightly. However, the wide angle cameras provide a fairly realistic portrayal of what one would see looking out across Mars from the Orbiter. Notable in this image are the late afternoon clouds and hazes that are concentrated within the Valles Marineris canyon system.
Launched on November 7, 1996, Mars Global Surveyor entered Mars orbit on Thursday, September 11, 1997. From the planned 400 km (248 mi) orbit altitude, MOC wide angle images will be 2-4 times higher resolution than these pictures.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Voir l'image PIA00991: Valles Marineris sur le site de la NASA.
Martian "fretted terrain" occurs in regions of buttes and mesas that stand at the erosional margin where northern low-lying plains meet the higher-standing cratered uplands. Found mostly in the mid-northern latitudes, some of the best examples of fretted terrain occur in Deuteronilus Mensae. Here, the interaction of the process that creates the mesas and buttes, the processes that modify these surfaces after they form, and the relationship of both of these processes with the "near-instantaneous" event that formed the large crater Lyot, provide us places to look to decipher this small but important piece of martian geological history. Part of that effort requires us to acquire compositional information--from the Mars Global Surveyor Thermal Emission Spectrometer (TES), from the Thermal Infrared Mapping Spectrometer (THEMIS) and Gamma Ray Spectrometer (GRS) on the 2001 Mars Odyssey mission, and from color images such as these taken by Mars Global Surveyor's Mars Orbiter Camera. Subtle and not-so-subtle color variations seen in this composite of MOC images M23-01279 and M23-01280 (acquired January 19, 2001) trace both the movement of dark sand of possible volcanic origin and fresh, dark outcrops of unweathered bedrock.
Voir l'image PIA03209: Lyot Crater and Northern Deuteronilus Mensae sur le site de la NASA.
This Mars Global Surveyor Mars Orbiter Camera narrow angle image (top) shows an intermountain valley floor in the Libya Montes region of Mars. Its regional setting is seen in the wide angle color mosaic (Figure A). The Libya Montes were formed by the giant impact that created the ancient Isidis basin. The Libya Mountains and valleys--like the one shown here--were subsequently modified and eroded by other processes, including wind, impact cratering, and flow of liquid water to make the small valley that runs across the middle of the scene. Until the mission was canceled, the Libya Montes region was among the top two candidates for the Mars Surveyor 2001 Lander. This image, illuminated by sunlight from the left, covers an area 3 kilometers (1.9 miles) wide and 19 kilometers (11.8 miles) long. The scene is located near 1.5°N, 278.4°W and was acquired on June 27, 1999. The high resolution color view (top) was created by combining the colors derived from Mars Orbiter Camera Wide Angle views of the region obtained in May 1999 (Figures A and B) with the high resolution view obtained in June 1999 (Figure C).
Voir l'image PIA02395: A Valley in the Libya Montes sur le site de la NASA.
Hundreds of layers of similar thickness, texture, and pattern have been exposed by erosion in a 64 kilometer-wide (40 mile-wide) impact crater in western Arabia Terra at 8°N, 7°W. In other words, these layers provide a record of repeated, episodic changes that took place at some time far in the martian past, when this particular impact crater was the site of sediment deposition. Layers toward the center of the crater are nearly horizontal, but those closer to or draping over the crater walls are tilted (geologist use the term dipping) toward the basin center. These relationships suggest that the sediments that created these layers were deposited from above--perhaps by settling out of the martian atmosphere, or perhaps by settling out of water that might have occupied this crater as a lake.
The context view (above) was taken by the Viking 1 orbiter in 1978; in it, north is up and sunlight illuminates the scene from the right. The three Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) narrow angle (high resolution) views (PIA02840, PIA02841, PIA02842) sample layer outcrops that were previously not known to exist in this crater. Each MOC image is illuminated from the left. Dark material in PIA02841 and PIA02840 (this release) is windblown sand; in PIA02840 (this release), this sand enhances the appearance of the layers.Note: In the context image above, the boxes marked A, B, and C refer to PIA02842, PIA02841, and PIA02840 (this release) respectively.
Voir l'image PIA02840: Layered Material in West Arabia Terra Crater sur le site de la NASA.
In October 2006, Northern Mars is near the middle of its summer, and the continued southern movement of the sun will have two main impacts on imaging: The illumination will get worse as eventually the entire polar region will be in darkness during winter, and northern hemispheric dust storms and polar cloudiness will obscure the surface. Because now is the best time to be imaging the north polar region until 2008, the team using the Context Camera on NASA's Mars Reconnaissance Orbiter is devoting much of its imaging resources to acquiring images of the polar region. This image shows a north polar mosaic from the orbiter's Mars Color Imager inscribed with rectangles indicating the coverage acquired by Context Camera in less than two weeks of September and October, 2006. Following conjunction (when Mars is nearly behind the sun from Earth's perspective), the team will devote as much of November as the atmosphere permits to imaging the polar region.Marked in red on this map is the footprint of the Context Camera image shown at PIA01930.
Early spring typically brings dust storms to northern polar Mars. As the north polar cap begins to thaw, the temperature difference between the cold frost region and recently thawed surface results in swirling winds. The choppy dust clouds of at least three dust storms are visible in this mosaic of images taken by the Mars Global Surveyor spacecraft in 2002. The white polar cap is frozen carbon dioxide.
Voir l'image PIA10789: Early Spring Dust Storms at the North Pole of Mars sur le site de la NASA.
Twelve orbits a day provide the MOC wide angle cameras a global "snapshot" of weather patterns across the planet. Here, bluish-white water ice clouds hang above the Tharsis volcanoes. The map is a mosaic of 24 images taken on a single northern summer day in April 1999.
The above color composite images, obtained by Mars Global Surveyor's camera on June 4, 1998, illustrate this Martian "weather report." Most of the thick, white clouds seen here occur north of latitude 35°N (roughly equivalent to Albuquerque NM, Memphis TN, and Charlotte, NC). Fog (seen as bright orange because it is lighter than the ground but some of the ground is still visible) occupies the lowest portions of the Kasei Valles outflow channel around 30°N and at 25°N.
Several different types of cloud features are seen. The repetitious, wash-board pattern of parallel lines are "gravity wave clouds". These commonly form, in the lee--downwind side-- of topographic features such as mountain ranges (on Earth) or crater rims (on Mars), under very specific atmospheric conditions (low temperatures, high humidity, and high wind speeds). In this area, the wave clouds are lower in the atmosphere than some of the other clouds. These other clouds show attributes reflecting more the regional weather pattern, occasionally showing the characteristic "slash" shape (southwest to northeast) of a weather front. These clouds probably contain mostly crystals of water ice but, depending on the temperature at high altitude (and more likely closer to the pole), some could also contain frozen carbon dioxide ("dry ice").
MOC images 34501 (the red wide angle image) and 34502 (the blue wide angle image) were obtained on Mars Global Surveyor's 345th orbit about the planet. The pictures were taken around 5: 34 p.m. PDT on June 4, 1998. Winter in the northern hemisphere began in mid-February, 1998, and continues to mid-July, 1998.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.
Voir l'image PIA01436: Detailed Cloud Patterns in Martian Northern Hemisphere sur le site de la NASA.
1 October 2006
These images capture what Mars typically looks like in mid-afternoon at Ls 121°. In other words, with the exception of occasional differences in weather and polar frost patterns, this is what the red planet looks like this month (October 2006).
Six views are shown, including the two polar regions. These are composites of 24-26 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global mapping images acquired at red and blue wavelengths. The 'hole' over the south pole is an area where no images were obtained, because this polar region is enveloped in wintertime darkness.
Presently, it is summer in the northern hemisphere and winter in the southern hemisphere. Ls, solar longitude, a measure of the time of year on Mars. Mars travels 360° around the Sun in 1 Mars year. The year begins at Ls 0°, the start of northern spring and southern autumn. Northern summer/southern winter begins at Ls 90°, northern autumn/southern spring start at Ls 180°, and northern winter/southern summer begin at Ls 270°.
Ls 121° occurs in the middle of this month (October 2006). The pictures show how Mars appeared to the MOC wide angle cameras at a previous Ls 121° in February 2001. The six views are centered on the Tharsis region (upper left), Acidalia and Mare Eyrthraeum (upper right), Syrtis Major and Hellas (middle left), Elysium and Mare Cimmeria (middle right), the north pole (lower left), and the south pole (lower right).
This is a wide angle view of the martian north polar cap as it appeared to the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) in early northern summer. The picture was acquired on March 13, 1999, near the start of the Mapping Phase of the MGS mission. The light-toned surfaces are residual water ice that remains through the summer season. The nearly circular band of dark material surrounding the cap consists mainly of sand dunes formed and shaped by wind. The north polar cap is roughly 1100 kilometers (680 miles) across.
Voir l'image PIA02800: The Martian North Polar Cap in Summer sur le site de la NASA.
Figure 1:
White boxes indicate
location high resolution views
Figure 2:
Context in THEMIS IR
mosaic of Eberswalde Crater;
North is Down
Voir l'image PIA04293: Eberswalde Delta in High Resolution sur le site de la NASA.
10 November 2004
This is a perspective view of the Charitum Montes, the mountain range that bounds southern Argyre Planitia, created by combining red and blue Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle images with topography from the MGS Mars Orbiter Laser Altimeter (MOLA). Carbon dioxide frost coats some of the hills, craters, and mountainsides in this southern springtime image. The picture is located near 57°S, 43°W. North is toward the top, south toward the bottom. Sunlight illuminates the scene from the upper left. The area shown is about 355 km (220 miles) wide. A smaller portion of this image was previously released in July 2003 as "Frosty Mountains."
