The conversation at AAAS today about the search for life on Mars was, well, pretty much the same thing we always hear. Follow the water! NASA scientists, and others, looking for that elusive organic matter are fired up about possible subsurface oceans and ice fields that *could be* teeming with aliens. There is evidence of mineralization, the polar regions have sedimentary deposits similar to those that exist at the base of glaciers on earth, and topography of the planet suggests rain flow.
At the same time, researchers are talking about what, exactly, fossilized alien life would look like. Their bet is that if we do find something it will be microbial. In other words, it will look just like fossilized versions that gooey green stuff that grows around sulfuric ponds at Yellowstone. Searching the fossil record for traces of life that look like fossils here on earth may be our only chance at identifying life that's now long gone.
But, no matter how excited I get when I think about life on other worlds, there are a few questions that I just can't get away from. First, why are we so sure that life on an alien world will look exactly the same as life here on earth? Should we really be looking for microbes that we recognize? Are we painting ourselves into a corner by assuming that the fossil record might not be something completely new that exceeds our wildest imaginations?
The other thing I've got to ask, and it's a bit of a downer really, is how blinded are we by our desperation to find life? How much of this evidence is real and how much is created by a deep-seeded need for there to be something bigger then ourselves?
I'll leave you pondering one last note, brought up by Tori Hoehler, an Astrobiologist at NASA's Ames Research Center: Water is only a binary indicator of life. To have life you must also have raw materials, energy to feed those materials, and the clement conditions to support it. The search for life on Mars is much bigger then simply proving that water flows below the dry red dust on the surface above.
