Clays Shed Light on Water, Suggest Past Mars Microbes

By Andrea Thompson Senior Writer posted: 07 August 2008 02:00 pm ET

Clay deposits found in one of the oldest riverbed-like channels on Mars shows some unusual signatures that may shed light on the history of water — and possibly life — on the red planet.

Observations made by an instrument onboard NASA's Mars Reconnaissance Orbiter (MRO), currently circling the planet, already have shown substantial clay deposits that formed about 4 billion years ago in two regions of Mars, Mawrth Vallis and Nili Fossae, that indicate that water was more widespread in those areas than was initially thought. Those findings were detailed in the July 17 issue of the journal Nature.

Now, a new study, detailed in the Aug. 8 issue of the journal Science, took a closer look at the clays in the Mawrth Vallis region and found that they lie in a uniform sequence of layers that indicates that the chemistry of water there changed over time.

""We see different clays, but the way we see them there, it's kind of like ... a layer cake, where we, every time we, every place we get a glimpse of what's there, it's the same order," said study leader Janice Bishop of the SETI Institute in Mountain View, Calif.

More at www.space.com