HiRISE Science Team wrote:Active Gullies in Crater Dune Field, Southern Polar Region (ESP_022255_1095)
These dune gullies are located in an unnamed crater just north of the Richardson Crater, which also contain dune gullies.
HiRISE is monitoring the seasonal activity of gullies in this location and in other dune fields in the southern midlatitudes and northern polar region.
Dan Berman wrote:Lobate Flow Feature in Eastern Hellas (ESP_022494_1385)
This image captures a tongue-shaped lobate flow feature along an interior crater wall located in eastern Hellas Planitia.
The flow feature is several kilometers long and about 1 kilometer wide with a partial double inner ridge and raised outer margin. The flow feature’s surface is highly pitted and generally devoid of impact craters. Similar flow features are found in many other craters throughout the Southern mid-latitudes of Mars, particularly in this region east of Hellas.
Studies of these flow features have determined that this type of flow feature predominantly form on pole-facing slopes of crater walls in the southern mid-latitudes. This polar-facing preference has implications for the amount of solar isolation these slopes are receiving, which may be a result of recent climate change due to shifts from low to high obliquity. Degraded, potentially ice-rich mantling deposits can be seen throughout the image as well. …
Credit: NASA/JPL/University of ArizonaGinny Gulick wrote:Terraced Eastern Wall along the Middle Reach of Ma'adim Vallis (ESP_022848_1595)
This image was originally suggested as part of the HiRISE Quest Student Image Challenge by Ms. Kathleen Hartrum's after school science club at Conestoga Middle School in Beaverton, Oregon. Students were interested in learning whether this region of Ma'adim Vallis preserved any evidence for past water flow processes at HiRISE resolution.
Ma'adim Vallis is one of the largest ancient valley systems on Mars. Located in the Southern Highlands it extends southwards over 700 kilometers before terminating in Gusev Crater where the Spirit rover landed and explored. This HiRISE image provides a high resolution view of a portion of the eastern valley wall midway down the valley system.
In this HiRISE image, numerous trough-like channels on the lower wall and terrace region suggest that water flowed in Ma'adim Vallis in the ancient past. …
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HiRISE PDS Release: July 2011 (Orbits 22,300—22,699)