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Mineralogical Diversity in Nili Fossae (PSP_009138_2025) August 26, 2008

Posted by jtintle in Planets, Space Fotos.
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Mineralogical Diversity in Nili Fossae

Credit:

NASA/JPL/University of Arizona

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Explanation:

There is evidence of phyllosilicate material (clays) throughout this region, named Nili Fossae. The evidence comes from the OMEGA experiment on the European Space Agency’s Mars Express spacecraft and CRISM on the Mars Reconnaissance Orbiter, infrared spectrometers that can identify minerals on the surface of Mars.

In the Nili Fossae region, the spectrometers have found remarkable diversity in surface composition. Because of the evidence for clays and other interesting geology, Nili Fossae is also being considered as a landing site for the Mars Science Laboratory rover.

HiRISE has targeted several places where OMEGA and CRISM show extreme diversity, with this being one example. In this specific area, low-calcium pyroxene (LCP) materials are adjacent to these clays. The cracked terrain regions evident at the highest resolution provide clues to the sequence of events which occurred in Nili Fossae.

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Fresh Double-Layered Ejecta Crater (PSP_009160_2350) August 25, 2008

Posted by jtintle in Planets, Space Fotos.
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Fresh Double-Layered Ejecta Crater

Credit:

NASA/JPL/University of Arizona

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Explanation:

This scene features a high latitude, northern hemisphere crater with double-layered ejecta. The sharp rim and lack of small superposed craters indicates that this crater is relatively young.

The semi-circular feature that parallels the crater rim is a terrace that probably formed as part of the crater wall collapsed into the center. The circular mound in the center likely formed at the same time as the crater itself. Large craters on Mars can have central peaks; this crater looks like it was on the cusp of having one. The linear features surrounding the crater on its ejecta are striations that formed during the impact as material and wind exploded out from the center.

At the bottom of the scene is a very distinct ejecta flow lobe (lobate ejecta). Lobate ejecta is thought to form when an impact occurs on a surface with lots of volatiles—ices that quickly turn to gas when they are heated. The gases help make the ejecta flow like a fluid.

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