July 17, 2007
Dr. Ralph Harvey studies rocks, especially ones that aren’t originally from Earth, and his talk focused on a collection of meteor rocks found around the world that have been shown to be from Mars. The rocks, combined with data from telescopes and probes sent to Mars, suggest just how much water was probably once on Mars and about how long ago that was. Harvey described how the meteors’ composition, mineral deposits, and evidence of stress in the meteors could be read to find out about the history of the Mars environment and the circumstances under which the rock came to Earth. Martian geology also shows strong evidence of ancient water flows, although those riverbeds and deltas could also have come from lava flows.
Harvey advocates caution and skepticism when addressing the possibilities of water and life on Mars, and described other likely explanations for the data we have. Mars could have been covered in ice instead of water, for example, or the methane found in Martian rocks could have come from lifeless reactions between water and rocks instead of biological reactions. He also has a sense of humor about working with space rocks, and there were plenty of Martian beavers and especially cows in his PowerPoint, illustrating that we really don’t know what’s out there until we go and see for ourselves.