To reply to Baker, it seems to me if there was widespread microbial life on Mars once, it'd still be there now. Do you believe that if Earth lost most of its atmosphere, its oceans, and became cold -- but gradually over a billion years -- that would extinguish all life? I do not. First, there actually were several "snowball Earth" eras where the whole planet was frozen over about 700 M years ago for around 20 M years or more. The equator in that era was as cold as modern-day Antarctica. Second, the so-called "deep biosphere" (estimated to contain anywhere from 1% to over 50% of all earth's biomass) would be virtually unaffected. And that is without any Darwinian adaption needed at all. With adaption, it gets more speculative, but there's a big free energy source on Mars with (1) the sun and (2) perchlorates near surface, and that's plenty of incentive for adaption to try to use it, with the deep biosphere providing a continually available reservoir of safeguarded life that can keep trying to find the right adaptions to handle the surface, no matter what. Hence: it still seems to me that the widespread unused surface perchlorates on Mars are a strong argument that (1) there is no life and (2) never was any. Why isn't everybody saying that? I can make some highly disparaging guesses related to (a) their psychology and (b) the fact they all want to keep the myth alive to get funding. -- Warren D. Smith http://RangeVoting.org <-- add your endorsement (by clicking "endorse" as 1st step)