NASA MAGELLAN MISSION (1989-1994)
Maat mons (8,000 m- 26,246ft)
Venus
photographed in 1990-92 in Alta Regio V236 and Stanton V 38 Quadrangle
The mountain
Maat Mons (8,000 m - 26,246ft or 8 km - 5.mi according to the way to measure mountains outside Earth planet) is a massive shield volcano located on the solar system planet Venus. Maat Mons, named for an Egyptian goddess of truth and justice, is the second-highest mountain, and the highest volcano, on the planet Venus.
Venus, named for the ancient Roman goddess of love and beauty, is the second planet from the sun and the closest planetary neighbor of Earth. Similar in structure and size to Earth, Venus spins slowly in the opposite direction most planets do. Its thick atmosphere traps heat in a runaway greenhouse effect, making it the hottest planet in our solar system with surface temperatures hot enough to melt lead. Glimpses below the clouds reveal volcanoes and deformed mountains.
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 has a large summit caldera, 28x31 km in size. Within the large caldera there are at least five smaller collapse craters, up to 10 km in diameter. A chain of small craters 3–5 km in diameter extends some 40 km along the southeast flank of the volcano, but rather than indicating a large fissure eruption, they seem to also be formed by collapse: full resolution imagery from the Magellan probe reveals no evidence of lava flows from these craters.
At least two large scale structural collapse events seem to have occurred in the past on Maat Mons.
Radar sounding by the Magellan probe revealed evidence for comparatively recent volcanic activity at Maat Mons, in the form of ash flows near the summit and on the northern flank.
Intriguingly for planetary geologists, atmospheric studies carried out by the Pioneer Venus probes in the early 1980s revealed a considerable variation in the concentrations of sulfur dioxide (SO2) and methane (CH4) in Venus' middle and upper atmosphere. One possible explanation for this was the injection of volcanic gases into the atmosphere by Plinian eruptions at Maat Mons.
Although many lines of evidence suggest that Venus is likely to be volcanically active, present-day eruptions at Maat Mons have not been confirmed.
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The image capturer
The Magellan spacecraft, named after the 16th century Portuguese explorer whose expedition first circumnavigated the Earth, was launched May 4, 1989, and arrived at Venus on August 10, 1990. Magellan's solid rocket motor placed it into a near-polar elliptical orbit around the planet. During the first 8-month mapping cycle around Venus, Magellan collected radar images of 84% of the planet's surface, with resolution 10 times better than that of the earlier Soviet Venera 15 and 16 missions. Altimetry and radiometry data also measured the surface topography and electrical characteristics.During the extended mission, two further mapping cycles from May 15, 1991 to September 14, 1992 brought mapping coverage to 98% of the planet, with a resolution of approximately 100m.
Precision radio tracking of the spacecraft will measure Venus' gravitational field to show the planet's internal mass distribution and the forces which have created the surface features. Magellan's data will permit the first global geological understanding of Venus, the planet most like Earth in our solar system.
Magellan Synthetic Aperture Radar (SAR) 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.
Source: - NASA Jet Propulsion Laboratory / CalTech