Mars Dry Areas More Extensive than Thought

If Mars had oceans or lakes, it wasn’t for long, at least in the Syrtis Major region.  Results of observations of the thermal emission imaging system (THEMIS) aboard the 2001 Mars Odyssey reveal about four times as much olivine as previously recognized in the Nili Fossae adjacent to the Syrtis volcanic shield.  Olivine quickly degrades in the presence of water.  Philip R. Christensen, principal investigator, who published the results in the June issue of Geology,¹ believes eruptive volcanoes were the primary source of the olivine-rich basalts, not intrusive processes like dikes or sills.
    The report on Mars Daily says the area studied is 11 times larger than the big island of Hawaii.  Co-author Victoria Hamilton said that finding this much olivine in a “very old region of Mars” was intriguing, and suggests that this area of Mars, at least, “has not seen much water.”
    Nevertheless, other areas look like something flowed.  Mars Express released an image of Ares Valles (near where the Mars Pathfinder rover landed) that looks like an extensive flood plain.  Perhaps volcanic heat melted frozen groundwater for a brief flooding episode some time long ago.
Update 06/06/2005: News@Nature reported that this could explain the methane.  Rather than coming from living organisms, the methane could emerge from the olivine in a process called serpentinization.  Chris Oze (Dartmouth) said, “I’d love to see bugs, but you can’t just go on hope.  You have to consider the geological options.”  Apparently, it would not require that much olivine to do the job, and now there’s probably more around than first expected.

¹Hamilton and Christensen, “Evidence for extensive, olivine-rich bedrock on Mars,” Geology, Vol. 33, No. 6, pp. 433�436, doi: 10.1130/G21258.1.

Even if Mars had lots of water, and even if its atmosphere was able to shield out the harmful radiation reaching the surface, it would not necessarily have had life.  This just erodes the hopes of astrobiologists even further.  About the only lively thing going on is the occasional dust devil passing by (see movie taken by Spirit).