This false-color image shows the volcano Sapas Mons, which is located in the broad equatorial rise called Atla Regio (8 degrees north latitude and 188 degrees east longitude). The area shown is approximately 650 kilometers (404 miles) on a side. Sapas Mons measures about 400 kilometers (248 miles) across and 1.5 kilometers (0.9 mile) high. Its flanks show numerous overlapping lava flows. The dark flows on the lower right are thought to be smoother than the brighter ones near the central part of the volcano. Many of the flows appear to have been erupted along the flanks of the volcano rather than from the summit. This type of flank eruption is common on large volcanoes on Earth, such as the Hawaiian volcanoes. The summit area has two flat-topped mesas, whose smooth tops give a relatively dark appearance in the radar image. Also seen near the summit are groups of pits, some as large as one kilometer (0.6 mile) across. These are thought to have formed when underground chambers of magma were drained through other subsurface tubes and lead to a collapse at the surface. A 20 kilometer-diameter (12-mile diameter) impact crater northeast of the volcano is partially buried by the lava flows. Little was known about Atla Regio prior to Magellan. The new data, acquired in February 1991, show the region to be composed of at least five large volcanoes such as Sapas Mons, which are commonly linked by complex systems of fractures or rift zones. If comparable to similar features on Earth, Atla Regio probably formed when large volumes of molten rock upwelled from areas within the interior of Venus known as'hot spots.' Magellan is a NASA spacecraft mission to map the surface of Venus with imaging radar. The basic scientific instrument is a synthetic aperture radar, or SAR, which can look through the thick clouds perpetually shielding the surface of Venus. Magellan is in orbit around Venus which completes one turn around its axis in 243 Earth days. That period of time, one Venus day, is the length of a Magellan mapping cycle. The spacecraft completed its first mapping cycle and primary mission on May 15, 1991, and immediately began its second cycle. During the first cycle, Magellan mapped more than 80 percent of the planet's surface and the current and subsequent cycles of equal duration will provide complete mapping of Venus. Magellan was launched May 4, 1989, aboard the space shuttle Atlantis and went into orbit around Venus August 10, 1990.

Voir l'image PIA00203: False Color Image of Volcano Sapas Mons sur le site de la NASA.

PIA00102: Venus - 3D Perspective View of Estla Regio

A portion of western Eistla Regio is displayed in this three-dimensional perspective view of the surface of Venus. The viewpoint is located 1,100 kilometers (682 miles) northeast of Gula Mons at an elevation of 7.5 kilometers (4.6 miles). Lava flows extend for hundreds of kilometers across the fractured plains shown in the foreground to the base of Gula Mons. The viewpoint is to the southwest with Gula Mons appearing at the left just below the horizon. Gula Mons, a 3 kilometers (1.8 miles) high volcano, is located at approximately 22 degrees north latitude, 359 degrees east longitude. Sif Mons, a volcano with a diameter of 300 kilometers (180 miles) and a height of 2 kilometers (1.2 miles), appears to the right of Gula Mons. The distance between Sif Mons and Gula Mons is approximately 730 kilometers (453 miles). Magellan synthetic aperture radar data is combined with radar altimetry to develop a three-dimensional map of the surface. Ray tracing (rays as if from a light source are cast in a computer to intersect the surface) simulate a perspective view. Simulated color and a digital elevation map developed by Randy Kirk of the U.S. Geological Survey, are used to enhance small scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. The image was produced at the JPL Multimission Image Processing Laboratory by Eric De Jong, Jeff Hall and Myche McAuley, and is a single frame from a video released at a March 5, 1991, JPL news conference.

Voir l'image PIA00102: Venus - 3D Perspective View of Estla Regio sur le site de la NASA.

PIA00105: Venus - Simulated Color of Leda Planitia

This false color Magellan image shows a portion of Leda Planitia (plains) in the northern hemisphere of Venus, centered at 41 degrees north latitude, 52 degrees east longitude. The area is 220 kilometers (135 miles) wide and 275 kilometers (170 miles) long. This image was produced from Magellan radar data collected in Cycle 2 of the mission. Cycle 2 was completed January 15, 1992. The area was not imaged during the first cycle because of superior conjunction when the sun was between the Earth and Venus, preventing communication with the spacecraft. This image contains examples of several of the major geologic terrains on Venus and illustrates the basic stratigraphy or sequence of geologic events. The oldest terrains appear as bright, highly-fractured or chaotic highlands rising out of the plains. This is seen in the upper left, or northwest, quadrant of the image. The chaotic highlands, sometimes called tessera, may represent older and thicker crustal material and occupy about 15 percent of the surface of Venus. The circular ring structure in the lower left of the image is probably an impact crater. This 40 kilometer (25 miles) diameter crater has been given a proposed name, Heloise, after the French physician who lived from about 1098 to 1164 A.D. The crater was formed by the impact of an asteroid sometime before the plains lavas embayed and covered the region. The plains surround and embay the fractured highland tessera. Plains are formed by fluid volcanic flows that may have once formed vast lava seas which covered all the low lying surfaces. Plains comprise more than 80 percent of the surface of Venus. The most recent activity in the region is volcanism that produced the radar bright flows best seen in the upper right quadrant of the image. Those flows are similar to the darker plains volcanics, but apparently have more rugged surfaces that more efficiently scatter the radar signal back to the spacecraft. Thus the geologic sequence is early fracturing of the tessera, flooding by extensive plains lavas and scattered, less extensive individual flows on the plains surface. Impact cratering occurs throughout geologic history and provides a rough estimate of the time scale. Craters larger than a few kilometers in diameter form on Venus, as they do on Earth, at the rate of about one per million years, with smaller impacts much more frequent than larger ones. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft.

Voir l'image PIA00105: Venus - Simulated Color of Leda Planitia sur le site de la NASA.

PIA00220: Venus - Comparison of Initial Magellan Radar Test and Data Acquired in 4/91

This image compares Magellan data acquired in August 1990 during the initial test of the radar system (black and white insets) with data acquired by the spacecraft in April 1991 (color background). The area is in the southern hemisphere of Venus, and represents an area about 540 kilometers (330 miles) on a side, centered on latitude 35 degrees south and longitude 294 degrees east. The Magellan radar illuminates the surface from the left. The northern and eastern parts of the area consist of plains which appear moderately dark to dark on the radar image because they are relatively smooth at a scale comparable to the wavelength of the radar, 12.5 centimeters (about 5 inches). The bright terrain in the southwestern part of the image is about 500 to 700 meters (1640 to 2300 feet) higher than the plains; it is characterized by abundant faults and fractures, which appear as straight to gently curved bright lines. Many of these linear features are large enough to infer that they are grabens, which are troughs bounded on both sides by faults. However, many of them are too narrow to determine if they are faults or simply fractures that have roughened the surface. This elevated faulted and fractured region is part of a large east-west elongated ridge mapped by the Pioneer Venus radar altimeter; the portion shown here is about midway between Themis Regio and Tefnut Mons. The plains are probably underlain by volcanic lavas. The various shades indicate that minor differences in surface roughness are present, and these may be used to map out the distribution of different lavas. The small, bright patches on the plains represent places where the lava surfaces are relatively rough. Just left of the center of the image is a sharply defined volcanic crater about 15 kilometers (9 miles) in diameter. Immediately north of this crater are numerous round spots about 204 kilometers (102 miles) across that are small volcanic domes.

Voir l'image PIA00220: Venus - Comparison of Initial Magellan Radar Test and Data Acquired in 4/91 sur le site de la NASA.

PIA00481: Venus - Three-Dimensional Perspective View of Alpha Regio

A portion of Alpha Regio is displayed in this three-dimensional perspective view of the surface of Venus. Alpha Regio, a topographic upland approximately 1300 kilometers across, is centered on 25 degrees south latitude, 4 degrees east longitude. In 1963, Alpha Regio was the first feature on Venus to be identified from Earth-based radar. The radar-bright area of Alpha Regio is characterized by multiple sets of intersecting trends of structural features such as ridges, troughs, and flat-floored fault valleys that, together, form a polygonal outline. Directly south of the complex ridged terrain is a large ovoid-shaped feature named Eve. The radar-bright spot located centrally within Eve marks the location of the prime meridian of Venus. Magellan synthetic aperture radar data is combined with radar altimetry to develop a three-dimensional map of the surface. Ray tracing is used to generate a perspective view from this map. The vertical scale is exaggerated approximately 23 times. Simulated color and a digital elevation map developed by the U. S. Geological Survey are used to enhance small scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. The image was produced at the JPL Multimission Image Processing Laboratory by Eric De Jong, Jeff Hall, and Myche McAuley, and is a single frame from the movie released at the March 5, 1991, press conference.

Voir l'image PIA00481: Venus - Three-Dimensional Perspective View of Alpha Regio sur le site de la NASA.

PIA00254: Venus - 3D Perspective View of Maat Mons

Maat Mons is displayed in this three-dimensional perspective view of the surface of Venus. The viewpoint is located 560 kilometers (347 miles) north of Maat Mons at an elevation of 1.7 kilometers (1 mile) above the terrain. Lava flows extend for hundreds of kilometers across the fractured plains shown in the foreground, to the base of Maat Mons. The view is to the south with Maat Mons appearing at the center of the image on the horizon. Maat Mons, an 8-kilometer (5 mile) high volcano, is located at approximately 0.9 degrees north latitude, 194.5 degrees east longitude. Maat Mons is named for an Egyptian goddess of truth and justice. Magellan synthetic aperture radar data is combined with radar altimetry to develop a three-dimensional map of the surface. The vertical scale in this perspective has been exaggerated 22.5 times. Rays cast in a computer intersect the surface to create a three-dimensional perspective view. Simulated color and a digital elevation map developed by the U.S. Geological Survey, are used to enhance small-scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. The image was produced at the JPL Multimission Image Processing Laboratory.

Voir l'image PIA00254: Venus - 3D Perspective View of Maat Mons sur le site de la NASA.

PIA00266: Venus - Oblique View of Crater Riley

This Magellan full resolution radar mosaic centered at 14 degrees north latitude, 72 degrees east longitude, shows an oblique view of the impact crater Riley, named for Margaretta Riley, a 19th Century botanist. This view was prepared from two left-looking Magellan radar images acquired with different incidence angles. Because the relief displacements of the two images are different, depths from the crater rim to the crater floor and heights of the crater rim and flanks above the surrounding plains can be measured. The crater is 25 kilometers (15.5 miles) in diameter. The floor of the crater is 580 meters (1,914 feet) below the plains surrounding the crater. The crater's rim rises 620 meters (2,046 feet) above the plains and 1,200 meters (3,960 feet) above the crater floor. The crater's central peak is 536 meters (1,769 feet) high. The crater's diameter is 40 times the depth resulting in a relatively shallow appearance. The topography is exaggerated by 22 times to emphasize the crater's features. This oblique view was produced from two left-looking radar stereo image mosaics utilizing photogrammetric software developed by the Solar System Visualization Project and the Digital Image Animation Laboratory at JPL's Multimission Image Processing Laboratory.

Voir l'image PIA00266: Venus - Oblique View of Crater Riley sur le site de la NASA.

PIA00103: Venus - 3D Perspective View of Lavinia Planitia

Three impact craters are displayed in this three-dimensional perspective view of the surface of Venus. The center of the image is located at approximately 27 degrees south latitude, 339 degrees east longitude in the northwestern portion of Lavinia Planitia. The viewpoint is located southwest of Howe Crater, which appears centered in the lower portion of the image. Howe is a crater with a diameter of 37.3 kilometers (23.1 miles) located at 28.6 degrees south latitude, 337.1 degrees east longitude. Danilova, a crater with a diameter of 47.6 kilometers (29.5 miles), located at 26.35 degrees south latitude, 337.25 degrees east longitude, appears above and to the left of Howe in the image. Aglaonice, a crater with a diameter of 62.7 kilometers (38.9 miles), located at 26.5 degrees south latitude, 340 degrees east longitude, is shown to the right of Danilova. Magellan synthetic aperture radar data is combined with radar altimetry to develop a three-dimensional map of the surface. Rays cast in a computer intersect the surface to create a three-dimensional perspective view. Simulated color and a digital elevation map developed by the U.S. Geological Survey are used to enhance small-scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. The image was produced at the JPL Multimission Image Processing Laboratory and is a single frame from a video released at the May 29, 1991, JPL news conference.

Voir l'image PIA00103: Venus - 3D Perspective View of Lavinia Planitia sur le site de la NASA.

PIA00268: Venus - 3D Perspective View of Latona Corona and Dali Chasma

This computer-generated perspective view of Latona Corona and Dali Chasma on Venus shows Magellan radar data superimposed on topography. The view is from the northeast and vertical exaggeration is 10 times. Exaggeration of relief is a common tool scientists use to detect relationships between structure (i.e. faults and fractures) and topography. Latona Corona, a circular feature approximately 1,000 kilometers (620 miles) in diameter whose eastern half is shown at the left of the image, has a relatively smooth, radar-bright raised rim. Bright lines or fractures within the corona appear to radiate away from its center toward the rim. The rest of the bright fractures in the area are associated with the relatively deep (approximately 3 kilometers or 1.9 miles) troughs of Dali Chasma. The Dali and Diana Chasma system consist of deep troughs that extend for 7,400 kilometers (4,588 miles) and are very distinct features on Venus. Those chasma connect the Ovda and Thetis highlands with the large volcanoes at Atla Regio and thus are considered to be the "Scorpion Tail" of Aphrodite Terra. The broad, curving scarp resembles some of Earth's subduction zones where crustal plates are pushed over each other. The radar-bright surface at the highest elevation along the scarp is similar to surfaces in other elevated regions where some metallic mineral such as pyrite (fool's gold) may occur on the surface.

Voir l'image PIA00268: Venus - 3D Perspective View of Latona Corona and Dali Chasma sur le site de la NASA.

PIA00259: Venus - False Color of Bereghinya Planitia

This false color Magellan image shows a portion of Bereghinya Planitia (plains) in the northern hemisphere of Venus, centered at 31 degrees north latitude, 43 degrees east longitude. The area is 260 kilometers (160 miles) wide and 330 kilometers (200 miles) long. This image was produced from Magellan radar data collected in Cycle 2 of the mission. Cycle 2 was completed January 15, 1992. The area was not imaged during the first cycle because of superior conjunction when the sun was between the Earth and Venus, preventing communication with the spacecraft. This image contains examples of several of the major geologic terrains on Venus and illustrates the basic stratigraphy or sequence of geologic events. The oldest terrains appear as bright, highly-fractured or chaotic highlands rising out of the plains. This is seen in the upper right and lower left quadrants of the image. The chaotic highlands, sometimes called tessera, may represent older and thicker crustal material and occupy about 15 percent of the surface of Venus. Plains surround and embay the fractured highland tessera. Plains are formed by fluid volcanic flows that may have once formed vast lava seas which covered all the low lying surfaces. Plains comprise more than 80 percent of the surface of Venus. The most recent activity in the region is volcanism that produced the radar bright flows best seen in the lower right quadrant of the image. The lava flows in this image are associated with the shield volcano Tepev Mons whose summit is near the lower left corner of the image. The flows are similar to the darker plains volcanics, but apparently have more rugged surfaces that more efficiently scatter the radar signal back to the spacecraft. The geologic sequence is early fracturing of the tessera, flooding by extensive plains lavas and scattered, less extensive individual flows on the plains surface. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft.

Voir l'image PIA00259: Venus - False Color of Bereghinya Planitia sur le site de la NASA.

PIA00147: Venus - False Color Image of Alpha Regio

This Magellan radar image shows Alpha Regio, a topographic upland approximately 1,300 kilometers (806 miles) across which is centered on 25 degrees south latitude, 4 degrees east longitude. In 1963 Alpha Regio was the first feature on Venus to be identified from Earth based radar. The radar bright area of Alpha Regio is characterized by multiple sets of intersecting trends of structural features such as ridges, troughs and flat floored fault valleys that together form a polygonal outline. Circular to oblong dark patches within the complex terrain are local topographic lows that are filled with smooth volcanic lava. Complex ridged terrains such as Alpha, formerly called "tessera" in the Soviet Venera 15 and 16 radar missions and the Arecibo radar data, appear to be widespread and common surface expressions of Venusian tectonic processes. Directly south of the complex ridged terrain is a large ovoid shaped feature named Eve. The radar bright spot located centrally within Eve marks the location of the prime meridian of Venus. Magellan radar data reveals that relatively young lava flows emanate from Eve and extends into the southern margin of the ridged terrain at Alpha. The mosaic was produced by Eric de Jong and Myche McAuley in the JPL Multimission Image Processing Laboratory.

Voir l'image PIA00147: Venus - False Color Image of Alpha Regio sur le site de la NASA.

PIA00109: Venus - 3D Perspective View of Idem-Kuva

A corona is displayed in this computer-simulated view of the surface of Venus. The viewpoint is located 150 kilometers (93 miles) north of Gula Mons at a height of 1.6 kilometers (1 mile) above the corona. The corona has a diameter of 97 kilometers (60 miles). The proposed name for the corona is Idem-Kuva, a Finno-Ugraic harvest spirit. Lava flows extend for hundreds of kilometers across the fractured plains shown in the background. The viewpoint is to the north with Gula Mons to the south. Magellan synthetic aperture radar data is combined with radar altimetry to produce a three-dimensional map of the surface. Rays cast in a computer intersect the surface to create a three-dimensional perspective view. Simulated color and a digital elevation map developed by the U.S. Geological Survey are used to enhance small-scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 124 spacecraft. The image was produced at the JPL Multimission Image Processing Laboratory and is a single frame from a video released at a March 5, 1991, JPL news conference.

Voir l'image PIA00109: Venus - 3D Perspective View of Idem-Kuva sur le site de la NASA.

PIA00265: Venus - False Color of Volcanic Plains

This Magellan full-resolution mosaic of Venus, centered at 10 degrees north latitude, 301 degrees east longitude, shows an area replete with diverse volcanic features. The image, of an area 489 kilometers long by 311 kilometers wide (303 by 193 miles), is dominated by volcanic plains which appear mottled because of varying roughnesses of each solidified lava flow. The rougher the terrain the brighter it appears in the radar image. The small, bright bumps clustered in the left portion of the image are a grouping of small volcanoes called a shield field. Each shield volcano is approximately 2 to 5 kilometers (1.2 to 3.1 miles) in diameter and has very subdued relief. It is believed that the lava flows that make up each shield originates from a common source. To the right of the shield field is another type of volcano, called a scalloped dome. It is 25 kilometers (16 miles) in diameter and has a central pit. Some of the indistinct lobe-shaped pattern around the dome may either be lava flows or rocky debris which has fallen from the scalloped cliffs surrounding the domes. The small radial ridges characteristic of scalloped domes are remnants of catastrophic landslides. To the right of that feature is a large depression called a volcanic caldera. The caldera was formed when lava was expelled from an underground chamber, which when emptied, subsequently collapsed forming the depression. The feature furthermost to the east (right) is another scalloped dome, 35 kilometers (22 miles) in diameter. That feature is unusual in that lava came out through the southeastern margin, rafting a large portion of the dome for 20 kilometers (12 miles). The lava continues into the lower right portion of the area in the image. Its steep rounded boundaries suggest it was a very sticky, oozing lava. That same type of lava is what scientists propose formed the steep-sided domes such as the bright, round feature, slightly northeast of center. It is highly likely that the features are all part of a single volcanic complex, where a large body of molten rock formed beneath the surface feeding each of the volcanoes above. The presence of fractures in the west, partially surrounding the volcanoes supports this theory.

Voir l'image PIA00265: Venus - False Color of Volcanic Plains sur le site de la NASA.

PIA00107: Venus - 3D Perspective View of Sapas Mons

Sapas Mons is displayed in the center of this computer-generated three-dimensional perspective view of the surface of Venus. The viewpoint is located 527 kilometers (327 miles) northwest of Sapas Mons at an elevation of 4 kilometers (2.5 miles) above the terrain. Lava flows extend for hundreds of kilometers across the fractured plains shown in the foreground to the base of Sapas Mons. The view is to the southeast with Sapas Mons appearing at the center with Maat Mons located in the background on the horizon. Sapas Mons, a volcano 400 kilometers (248 miles) across and 1.5 kilometers (0.9 mile) high is located at approximately 8 degrees north latitude, 188 degrees east longitude, on the western edge of Atla Regio. Its peak sits at an elevation of 4.5 kilometers (2.8 miles) above the planet's mean elevation. Sapas Mons is named for a Phoenician goddess. The vertical scale in this perspective has been exaggerated 10 times. Rays cast in a computer intersect the surface to create a three-dimensional perspective view. Simulated color and a digital elevation map developed by the U.S. Geological Survey are used to enhance small-scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. The image was produced by the Solar System Visualization project and the Magellan Science team at the JPL Multimission Image Processing Laboratory and is a single frame from a video released at the April 22, 1992 news conference.

Voir l'image PIA00107: Venus - 3D Perspective View of Sapas Mons sur le site de la NASA.

PIA00246: Venus - 3D Perspective View of Eastern Edge of Alpha Regio

A portion of the eastern edge of Alpha Regio is displayed in this three-dimensional perspective view of the surface of Venus. The viewpoint is located at approximately 30 degrees south latitude, 11.8 degrees east longitude at an elevation of 2.4 kilometers (3.8 miles). The view is to the northeast at the center of an area containing seven circular dome-like hills. The average diameter of the hills is 25 kilometers (15 miles) with maximum heights of 750 meters (2,475 feet). Three of the hills are visible in the center of the image. Fractures on the surrounding plains are both older and younger than the domes. The hills may be the result of viscous or thick eruptions of lava coming from a vent on the relatively level ground, allowing the lava to flow in an even lateral pattern. The concentric and radial fracture patterns on their surfaces suggests that a chilled outer layer formed, then further intrusion in the interior stretched the surface. An alternative interpretation is that domes are the result of shallow intrusions of molten lava, causing the surface to rise. If they are intrusive, then magma withdrawal near the end of the eruptions produced the fractures. The bright margins possibly indicate the presence of rock debris or talus at the slopes of the domes. Resolution of the Magellan data is about 120 meters (400 feet). Magellan's synthetic aperture radar is combined with radar altimetry to develop a three-dimensional map of the surface. A perspective view is then generated from the map. Simulated color and a process called radar-clinometry are used to enhance small-scale structures. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. The image was produced by the JPL Multimission Image Processing Laboratory by Eric De Jong, Jeff Hall, Myche McAuley, and Randy Kirk of the United States Geological Survey, and is a single frame from the movie released at the May 29, 1991 Magellan news conference.

Voir l'image PIA00246: Venus - 3D Perspective View of Eastern Edge of Alpha Regio sur le site de la NASA.

PIA00233: Venus - 3D Perspective View of Eistla Regio

A portion of western Eistla Regio is displayed in this three-dimensional perspective view of the surface of Venus. The viewpoint is located 1,310 kilometers (812 miles) southwest of Gula Mons at an elevation of 0.78 kilometer (0.48 mile). The view is to the northeast with Gula Mons appearing on the horizon. Gula Mons, a 3 kilometer (1.86 mile) high volcano, is located at approximately 22 degrees north latitude, 359 degrees east longitude. The impact crater Cunitz, named for the astronomer and mathematician Maria Cunitz, is visible in the center of the image. The crater is 48.5 kilometers (30 miles) in diameter and is 215 kilometers (133 miles) from the viewer's position. Magellan synthetic aperture radar data is combined with radar altimetry to develop a three-dimensional map of the surface. Rays cast in a computer intersect the surface to create a three-dimensional perspective view. Simulated color and a digital elevation map developed by the U.S. Geological Survey, are used to enhance small-scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. The image was produced at the JPL Multimission Image Processing Laboratory and is a single frame from a video released at the March 5, 1991, JPL news conference.

Voir l'image PIA00233: Venus - 3D Perspective View of Eistla Regio sur le site de la NASA.

PIA00234: Venus - 3D Perspective View of Gula Mons

Gula Mons is displayed in this computer-simulated view of the surface of Venus. The viewpoint is located 110 kilometers (68 miles) southwest of Gula Mons at the same elevation as the summit, 3 kilometers (1.9 miles) above Eistla Regio. Lava flows extend for hundreds of kilometers across the fractured plains. The view is to the northeast with Gula Mons appearing at the center of the image. Gula Mons, a 3 kilometer (1.9 mile) high volcano, is located at approximately 22 degrees north latitude, 359 degrees east longitude in western Eistla Regio. Magellan synthetic aperture radar data is combined with radar altimetry to produce a three-dimensional map of the surface. Rays cast in a computer intersect the surface to create a three-dimensional perspective view. Simulated color and a digital elevation map developed by the U.S. Geological Survey are used to enhance small-scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. The image was produced by the JPL Multimission Image Processing Laboratory and is a single frame from a video released at the March 5, 1991, JPL news conference.

Voir l'image PIA00234: Venus - 3D Perspective View of Gula Mons sur le site de la NASA.

PIA00106: Venus - 3D Perspective View of Maat Mons

Maat Mons is displayed in this computer generated three-dimensional perspective of the surface of Venus. The viewpoint is located 634 kilometers (393 miles) north of Maat Mons at an elevation of 3 kilometers (2 miles) above the terrain. Lava flows extend for hundreds of kilometers across the fractured plains shown in the foreground, to the base of Maat Mons. The view is to the south with the volcano Maat Mons appearing at the center of the image on the horizon and rising to almost 5 kilometers (3 miles) above the surrounding terrain. Maat Mons is located at approximately 0.9 degrees north latitude, 194.5 degrees east longitude with a peak that ascends to 8 kilometers (5 miles) above the mean surface. Maat Mons is named for an Egyptian Goddess of truth and justice. Magellan synthetic aperture radar data is combined with radar altimetry to develop a three-dimensional map of the surface. The vertical scale in this perspective has been exaggerated 10 times. Rays cast in a computer intersect the surface to crate a three-dimensional perspective view. Simulated color and a digital elevation map developed by the U.S. Geological Survey are used to enhance small-scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. The image was produced by the Solar System Visualization project and the Magellan Science team at the JPL Multimission Image Processing Laboratory and is a single frame from a video released at the April 22, 1992 news conference.

Voir l'image PIA00106: Venus - 3D Perspective View of Maat Mons sur le site de la NASA.

PIA00216: Venus - False Color of Sacajawea Petera

This Magellan image reveals Sacajawea Patera, a large, elongate caldera located in western Ishtar Terra on the smooth plateau of Lakshmi Planum. The image is centered at 64.5 degrees north latitude and 337 degrees east longitude. It is approximately 420 kilometers (252 miles) wide at the base. Sacajawea is a depression approximately 1.2 km (0.6 1.2 miles) deep and 120 by 215 km (74 by 133 miles) in diameter; it is elongate in a southwest northeast direction. The depression is bounded by a zone of circumferential curvilinear structures interpreted to be graben and fault scarps. These structures are space 0.5 to 4 km (0.3 to 2.5 miles) apart, are 0.6 to 4 km (0.4 to 2.5 miles) in width and up to 100 km (62 miles) in length. Extending up to 140 km (87 miles) in length from the southeast of the patera is a system of linear structures thought to represent a flanking rift zone along which the lateral injection and eruption of magma may have occurred. A shield edifice 12 km (7 miles) in diameter with a prominent central pit lies along the trend of one of these features. The impact crater Zlata, approximately 6 km (4 miles) in diameter is located within the zone of graben to the northwest of the patera. Few flow features are observed in association with Sacajawea, possibly due to age and state of degradation of the flows. Mottled bright deposits 4 to 20 km (2.5 to 12 miles) in width are located near the periphery and in the center of the patera floor within local topographic lows. Diffuse patches of dark material approximately 40 km (25 miles) in width are observed southwest of the patera, superimposed on portions of the surrounding graben. The formation of Sacajawea is thought to be related to the drainage and collapse of a large magma chamber. Gravitational relaxation may have caused the resultant caldera to sag, producing the numerous faults and graben that circumscribe the patera. Regions of complex, highly deformed tessera like terrain are located north and east of the patera and are seen in the upper portion of the image. Color has been added to this image to simulate the appearance of the Venus surface.

Voir l'image PIA00216: Venus - False Color of Sacajawea Petera sur le site de la NASA.

PIA00108: Venus - 3D Perspective View of Sif Mons

Sif Mons is displayed in this computer-simulated view of the surface of Venus. The viewpoint is located 360 kilometers (223 miles) north of Sif Mons at a height of 7.5 kilometers (4.7 miles) above the lava flows. Lave flows extend for hundreds of kilometers across the fractured plains shown in the foreground to the base of Sif Mons. The view is to the south. Sif Mons, a volcano with a diameter of 300 kilometers (186 miles) and a height of 2 kilometers (1.2 miles), appears in the upper half of the image. Magellan synthetic aperture radar data is combined with radar altimetry to produce a three-dimensional map of the surface. Rays, cast in a computer, intersect the surface to create a three-dimensional perspective view. Simulated color and a digital elevation map developed by the U.S. Geological Survey are used to enhance small-scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. The image was produced at the JPL Multimission Image Processing Laboratory and is a single frame from a video released at the March 5, 1991, JPL news conference.

Voir l'image PIA00108: Venus - 3D Perspective View of Sif Mons sur le site de la NASA.

PIA00258: Venus - False Color of Eistla Regio

This false color Magellan image shows a portion of Eistla Regio (region) in the northern hemisphere of Venus, centered at 1 degrees south latitude, 37 degrees east longitude. The area is 440 kilometers (270 miles) wide and 350 kilometers (220 miles) long. This image was produced from Magellan radar data collected in Cycle 2 of the mission. Cycle 2 was completed January 15, 1992. The area was not imaged during the first cycle because of superior conjunction when the sun was between the Earth and Venus, preventing communication with the spacecraft. This image contains examples of several of the major geologic terrains on Venus and illustrates the basic stratigraphy or sequence of geologic events. The oldest terrain appears as bright, highly fractured or chaotic highlands rising out of the plains. This is seen in the right half of the image. The chaotic highlands, sometimes called tessera, may represent older and thicker crustal material and occupy about 15 percent of the surface of Venus. The fractured terrain in this region has a distinctly linear structure with a shear-like pattern. Plains surround and embay the fractured highland tessera. Plains are formed by fluid volcanic flows that may have once formed vast lava seas which covered all the low lying surfaces. Plains comprise more than 80 percent of the surface of Venus. The most recent activity in the region is volcanism that produced the radar bright flows best seen in the upper left quadrant of the image. The flows are similar, in their volcanic origin to the darker plains volcanics, but apparently have more rugged surfaces that more efficiently scatter the radar signal back to the spacecraft. The geologic sequence is early fracturing of the tessera, flooding by extensive plains lavas, and scattered less extensive individual flows on the plains surface. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft.

Voir l'image PIA00258: Venus - False Color of Eistla Regio sur le site de la NASA.

PIA00272: Venus - Simulated Color of Ushas Mons

Ushas Mons, a 2-kilometer-high (1.25 mile) volcano in the southern hemisphere of Venus is shown in this Magellan radar image. The image is centered at 25 degrees south latitude, 323 degrees east longitude, and shows an area approximately 600 kilometers (360 miles) on a side. The volcano is marked by numerous bright lava flows and a set of north-south trending fractures, many of which appear to have formed after the lavas were erupted onto the surface. In the central summit area, however, younger flows remain unfractured. An impact crater can be seen among the fractures in the upper center of the image. The association of faulting and volcanism is common on this type of volcano on Venus, and is believed to result from a large zone of hot material upwelling from the Venusian mantle, a phenomenon known on Earth as a "hot spot." Simulated color is used to enhance small-scale structures. The simulated hues are based on color images recorded by the Venera 13 and 14 landing craft. The data were acquired during the third eight-month cycle of Magellan's radar mapping, which ended in September 1992. Several narrow gaps in the Magellan coverage are filled with low-resolution radar data obtained by the Earth-based Arecibo radio telescope. The image was produced by the Solar System Visualization Project and the Magellan Science Team at the Jet Propulsion Multimission Image Processing Laboratory. The Magellan mission is managed by JPL for NASA's Office of Space Science.

Voir l'image PIA00272: Venus - Simulated Color of Ushas Mons sur le site de la NASA.

PIA00200: Venus - False Color Perspective of Sif and Gula Mons

A portion of western Eistla Regio is shown in this three dimensional, computer-generated view of the surface of Venus. The viewpoint is at an elevation of 1.2 kilometers (0.75 mile) at a location 700 kilometers (435 miles) southeast of Gula Mons, the volcano on the right horizon. Gula Mons reaches 3 kilometers (1.8 miles) high and is located around 22 degrees north latitude and 359 degrees east longitude. Sif Mons, the volcano on the left horizon, has a diameter of 300 kilometers (186 miles) and a height of 2 kilometers (1.2 miles). Magellan imaging and altimetry data are combined to develop a three-dimensional computer view of the planet's surface. Simulated color based on color images from the Soviet Venera 13 and 14 spacecraft is added to enhance small-scale structure. This image was produced at JPL's Multimission Image Processing Laboratory by Eric De Jong, Jeff Hall and Myche McAuley. Magellan is a NASA spacecraft mission to map the surface of Venus with imaging radar. The basic scientific instrument is a synthetic aperture radar, or SAR, which can look through the thick clouds perpetually shielding the surface of Venus. Magellan is in orbit around Venus which completes one turn around its axis in 243 Earth days. That period of time, one Venus day, is the length of a Magellan mapping cycle. The spacecraft completed its first mapping cycle and primary mission on May 15, 1991, and immediately began its second cycle. During the first cycle, Magellan mapped more than 80 percent of the planet's surface and the current and subsequent cycles of equal duration will provide complete mapping of Venus. Magellan was launched May 4, 1989, aboard the space shuttle Atlantis and went into orbit around Venus August 10, 1990.

Voir l'image PIA00200: Venus - False Color Perspective of Sif and Gula Mons sur le site de la NASA.