Martian landform observations fill special journal issue
Mon Jan 11, 2010 at 20:25 UTC
Martian landforms shaped by winds, water, lava flow, seasonal icing and other forces are analyzed in 21 journal reports based on data from a camera orbiting Mars.
The research in a January special issue of Icarus testifies to the diversity of the planet being examined by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter.
Examples of the findings include:
- Valleys associated with light-toned layered deposits in several locations along the plateaus adjacent to the largest canyon system on Mars suggest low-temperature alteration of volcanic rocks by acidic water both before and after formation of the canyons.
- The youngest flood-lava flow on Mars, found in the Elysium Planitia region and covering an area the size of Oregon, is the product of a single eruption and was put in place turbulently over a span of several weeks at most.
- New details are observed in how seasonal vanishing of carbon-dioxide ice sheets in far-southern latitudes imprints the ground with fan-shaped and spider-shaped patterns via venting of carbon-dioxide gas from the undersurface of the ice.
High resolution image
The image comes from an observation made by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter on May 2, 2007.
Researchers have found that these bright layered deposits contain opaline silica and iron sulfates, consistent with low-temperature, acidic aqueous alteration of basaltic materials. They conclude that aqueous activity affected this plateau after formation of the nearby canyons. Although the source of water and sediment remains uncertain, the strong correlation between fluvial landforms and bright layered deposits in this region argues for sustained precipitation, surface runoff, and fluvial deposition occurring during Mars' Hesperian Era on the plateaus adjacent to Valles Marineris and along portions of canyon walls.
This image is one product from HiRISE observation PSP_003579_1755, centered at 4.7 degrees south latitude, 296.4 degrees east longitude. Other image products from this observation are available at http://hirise.lpl.arizona.edu/PSP_003579_1755.
Credit: NASA/JPL-Caltech/University of Arizona
On the left, color coding indicates relative elevation, based on three dimensional modeling from stereo pairs of images taken by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. The scale bar is 1 kilometer (0.62 mile). The reference key to the color coding is in meters relative to a zero index altitude for Mars (negative numbers, so lower elevations than the zero index). The range from highest (red) to lowest (dark blue) is about 170 meters (558 feet). The labels "A" and "B" indicate the locations of the two images on the right.
The images on the right are made from stereo-paired HiRISE observations and appear three dimensional when viewed through red-blue glasses. The features evident here are "phreatovolcanic cones" related to lava-water interactions. They can be used as indicators of where the lava flowed. The difference in elevation between "A" and "B" is more than 100 meters (328 feet), so the lava flow reached a peak depth of more than 100 meters in this area. It is also interesting that the cones are small where the lava was thin (B) and big where the lave was deeper (A). The scale bars are 50 meters (164 feet).
Credit: NASA/JPL-Caltech/University of Arizona
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