The effort to understand conditions on Mars leads researchers to
some of the most extreme environments on Earth, including
Chile's Atacama Desert. Although no plants or animals live in
the desert's super-dry core, microscopic organisms exist beneath
a crusty varnish on some rocks, which may be like some rocks on
Mars. Studying the Atacama rocks will help scientists design
experiments to look for microscopic life in Mars rocks. [Kim
Kuhlman] If you've ever hiked across a desert, you've probably
seen them -- reddish-brown or black rocks that look like they
have a glossy coating -- almost like they've been varnished.
Well, it turns out that some of them have. They're coated with
clay and manganese -- a mixture known as rock varnish. Similar
rocks may have been seen in pictures from the surface of Mars.
That could have important implications for life there, because
rock varnish could be formed by bacteria. KUHLMAN: Because it
has so much manganese in it, people like to think that it's got
to be formed by biology,