http://www.dlr.de/dlr/en/desktopdefault.aspx/tabid-10212/332_read-3409/year-... "Lichens from inhospitable parts of Earth have demonstrated their ability to survive even under the conditions on Mars – organisms that live at altitudes of up to 3500 metres, collected in Switzerland, and cyanobacteria and lichens from the Antarctic. "We observed these samples in a Martian climate for over a month in our Mars simulation chamber," says de Vera. The researchers recreated the Martian surface with various mineral constituents, using knowledge obtained from missions such as the NASA Mars rovers 'Opportunity' and 'Spirit'. In the chamber itself, they replicated the Martian atmosphere, which consists of 95 percent carbon dioxide, four percent nitrogen and trace gases such as argon and oxygen. A vacuum pump system then ensured six millibars of air pressure, which enabled the planetary researchers to simulate the Red Planet’s tenuous atmosphere. Special radiation sources ranging from the ultraviolet to the infrared replicated solar radiation on the surface of Mars. Finally, the organisms had to cope with temperatures that fluctuated between minus 50 degrees Celsius to plus 23 degrees Celsius." "We know that lichens and bacteria could survive and remain active on Mars for 34 days. But could the organisms continue to live in these conditions beyond this period, for years or even centuries? Unfortunately, this question will remain unanswered, as such lengths of time would exceed the scope of this experiment."