Starship Asterisk*

Alfred McEwen wrote:

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Cataracts in Kasei Valles (PSP_003513_2055)

Obviously these are not the kind of cataracts that can develop in the lenses of your eyes, but large erosional scallops that form in river channels, like the Niagara Falls draining the Great Lakes of North America.

Cataracts are large landforms, and this oblique image covers only a small area of the innermost channel. The ridged material on the channel floor may be a lava flow that followed this channel after it was initially carved by giant floods of water.

This is a stereo pair with PSP_002814_2055.

Christy Caudill wrote:

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Crater Rim Layers, Rubble, and Gullies (ESP_015984_1335)

This is a close view of the rim and upper wall of an impact crater on the Martian surface. The layers in enhanced color are exposed subsurface strata that are relatively resistant to erosion. Boulder-like rubble beyond the crater rim is scattered down the wall of the crater (down-slope is toward the lower left of the image).

Another feature of interest to Mars scientists is a large gully roughly 100 meters across. These gullies may have formed when water from melted ice on the crater walls, or from groundwater within the walls, assisted in transporting eroding material downslope.

Alfred McEwen wrote:

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A View of the Painted Desert Near Mawrth Vallis (ESP_016394_2045)

The clay-rich terrain surrounding Mawrth Vallis is one of the most scenic regions of Mars, a future interplanetary park. Here, we cut a long, oblique view into strips to see the full color coverage in more compact form.

The origin of these altered layers is the subject of continued debates, perhaps to be resolved by a future rover on the surface. We do know that these layers are very ancient, dating back to a time when the environment of Mars was wetter and more habitable, if there were any inhabitants.

This is a stereo pair with PSP_008245_2045.

Kristin Block wrote:

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Along the Floor of Coprates Chasma (ESP_018347_1660)

This image shows a small portion of the floor of Coprates Chasma, a large trough within the Valles Marineris system of canyons.

Although the exact sequence of events that formed Coprates Chasma is unknown, the ripples, mesas, and craters visible throughout the terrain point to a complex history involving multiple mechanisms of erosion and deposition. The main trough of Coprates Chasma ranges from 60 to 100 kilometers in width.

This is a stereo pair with ESP_026417_1660.