Aug 8 2008
From The Space Library
A team of scientists led by Janice L. Bishop of the SETI (Search for Extraterrestrial Intelligence) Institute announced in the journal Science that they had found geological evidence that water, and possibly microorganisms, had been present in Mars’s Mawrth Vallis region in the past. Using NASA’s MRO’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), the scientists had studied the layers of sediment comprising the 4 billion-year-old clay deposits of that region. The top layer of clay, which contained many aluminum deposits, had probably formed in a wet environment when other minerals were leached from the soil leaving large amounts of aluminum behind. Immediately below the top layer containing aluminum-rich clay was a layer of silica opal. Clay rich in reduced iron formed a still lower layer. A large body of water interacting with a lakebed of basaltic ash or rock probably formed the lowest layer, which is composed of iron and magnesium smectites. Bishop’s team noted that, on Earth, the actions of microorganisms frequently cause iron reduction in the soil. However, the team also stated that other forces could have been responsible, on Mars.
Andrea Thompson, “Clays Shed Light on History of Mars Water and Possibly Life,” Space.com, 7 August 2008, http://www.space.com/5709-clays-shed-light-history-mars-water-possibly-life.html (accessed 20 July 2011); see also Janice L. Bishop et al., “Phyllosilicate Diversity and Past Aqueous Activity Revealed at Mawrth Vallis, Mars,” Science 321, no. 5890 (8 August 2008): 830-833.
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