Life on Mars?

The discovery that a saltwater sea once existed on the surface of Mars - and the continued presence of subsurface water - greatly increased the chances that life may once have existed there, and that's all very exciting. But now comes much more suggestive evidence that life may exist there right now. Multiple groups have independently confirmed the presence of methane in the Martian atmosphere. Due to the thin atmosphere of Mars, any supply of methane would have be constantly replenished or disappear within a couple hundred years.

On Earth, there are organisms called methanogens - microbes that produce methane from hydrogen and carbon dioxide. These organisms do not need oxygen to thrive, and they are thought to be the type of microbes that could possibly live on Mars.

Scientists caution that the methane could be the result of volcanic activity, but none of the many spacecraft orbiting and analyzing Mars have seen any signs of active volcanism. However, active volcanic vents would also produce enough heat to melt some of the vast quantities of sub-surface ice, providing another favorable habitat for microbial life. The rovers, designed for geological work, do not have the proper equipment to test for the presence of microbes, though the failed Beagle project did. Hopefully, this will put a brake on the gathering momentum of the horribly shortsighted notion of terraforming Mars.

The important question, then, is whether life originated on one of the two planets and seeded the other through impacts or if it arose independently on both planets. If it's the latter, that is compelling, though not decisive, evidence that life is common throughout the universe. Next year, the Huygens probe will descend through the thick, methane-rich atmosphere of the Saturnian moon, Titan. Here's a fairly technical exploration of the possible sources for Titanic methane. Titan seems a poor model for harboring life, though I suspect that our current notions of "life" may be a little too focused on forms similar to terrestrial life.

Who knows? Regardless, this has turned out to be a pretty heady time to be an astronomer, hasn't it? For all my abiding interest in the subject, I took only one astronomy class during college - during my first semester at UNC, at 8:00 am MWF. Unfortunately, the intro class consisted largely of the professor turning off the lights to show slides, followed shortly by the thud of my head landing on the desk. I gave up the fight and just showed for the exams, passing the class by the skin of my teeth. Had it been an afternoon class (and had I not been so slavishly dedicated to the path of least resistance), my entire academic career might have been vastly different.