Reconnaissance Orbiter finds more evidence of water on the planet Mars

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Saturday, February 17, 2007

Tectonic fractures within the Candor Chasma region of Valles Marineris, Mars, retain ridge-like shapes as the surrounding bedrock erodes away. This points to past episodes of fluid alteration along the fractures and reveals clues into past fluid flow and geochemical conditions below the surface.

NASA's Mars Reconnaissance Orbiter has discovered more evidence on the Planet Mars that water may have flowed beneath the surface and that "cracks" that lead below the surface may have, at one time, been "habitable" for "microbial life," according to the head investigater for the orbiter's camera, Dr. Alfred McEwen. The location of the find is near the Candor Chasma canyon and images of the cracks were taken in September of 2006.

"This result shows how orbital observations can identify features of particular interest for future exploration on the surface or in the subsurface or by sample return. The alteration along fractures, concentrated by the underground fluids, marks locations where we can expect to find key information about chemical and perhaps biologic processes in a subsurface environment that may have been habitable," said McEwen.

According to NASA scientists, "mineralization" was found on the surface of the cracks and the crack's fractures. Scientists say the minerals became visible after layers of sand and dirt eroded away from the cracks. The minerals were likely placed on the rocks after dissolving in water and then evaporating onto the rocks, causing the minerals to become rock. Another possibility on how the minerals were placed there is that the "fluid" circulating on the rock was a gas, which might or might not have contained water.

"What caught my eye was the bleaching or lack of dark material along the fracture. That is a sign of mineral alteration by fluids that moved through those joints. It reminded me of something I had seen during field studies in Utah, that is light-tone zones, or 'haloes,' on either side of cracks through darker sandstone," said University of Arizona, Tucson geologist, Dr. Chris Okubo.

"The haloes visible along fractures seen in the Candor Chasma image appear to be slightly raised relative to surrounding, darker rock. This is evidence that the circulating fluids hardened the lining of the fractures, as well as bleaching it. The harder material would not erode away as quickly as softer material farther from the fractures," said a statement on NASA's website.

It is not clear how long the minerals might have been present or how long it took them to get on the rocks.

"It is hard to say how long ago the fluids were there - hundreds of millions or perhaps a billion years ago. But the fact that we see evidence for chemical reactions between the fluids and the rock means that the fluids were sitting there for quite a long time ... that's perhaps good if you want to look for any habitable areas that might support any biological activity," added Okubo.

"This publication is just the first of many, many to come. The analysis is based on test observations taken even before the start of our main science phase. Since then, Mars Reconnaissance Orbiter has returned several terabits of science data, sustaining a pace greater than any other deep space mission. This flood of data will require years of study to exploit their full value, forever increasing our understanding of Mars and its history of climate change," added Okubo.

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