Question

What are the latest advances in finding life on Mars? Which would be the most appropriate extremophiles to leave in Mars so that they can survive?

The most recent advances are indirect. Our spacecraft at Mars, particularly the two highly successful orbiters that have been mapping the planet for many months, continue to improve our understanding of Mars, particularly whether the "gullies" in the high-resolution orbiter images are recent and due to liquid water. There are many websites that discuss various interpretations of the gullies. You might start by looking at
http://www.solarviews.com/cap/mgs/PIA01033.htm and http://www.msss.com/mars_images/moc/e7_e12_captioned_rel/. On Earth, scientists continue to study terrestrial organisms that live in environments that are very cold and dry, such as the Atacama Desert in the Andes (see stories at http://astrobiology.arc.nasa.gov/). So far we have not found any extremophile from our planet that could survive and grow at the surface of Mars. The apparent requirement for all terrestrial life is liquid water, so it is unlikely that any of our lifeforms will grow on Mars unless we can get them to some place where the water is occasionally liquid (probably underground). That is why NASA search for life on Mars has the motto "Follow the water".

David Morrison
NAI Senior Scientist
June 24, 2003