16 December 2009

The Science of Extraterrestrials

Posted by Michael McFadden

Astrobiology is an emerging multidisciplinary field that asks one large question: Are we alone? In a particularly thought-provoking session, P33C Astrobiology and Society: Challenges and Opportunities, scientists presented the search for extraterrestrial life from many perspectives. The first half of the session was devoted to scientific projects and data involved in this search.

Image from NASA/JPLNASA scientist Michael Meyer gave an overview of our ever-changing perspective of life on Mars. Back in 1975, the Viking Landers described Mars as a barren desert incapable of hosting life. But more recent missions have overturned this idea; Mars is now known to have had a wet and dynamic past and many scientists consider it plausible that fossil evidence for life may exist. Some even find it likely that life currently thrives in the planet’s subsurface. The upcoming Mars Science Laboratory mission (seen in the picture here) is scheduled to land on the red planet in 2012. It will be larger than any previous lander and will rove the planet in search of the signs of life.

David Koch from NASA Ames Research Center presented information on the Kepler mission, which is currently monitoring 100,000 stars for signs of Earth-like planets. Kepler hopes to answer the question of how common Earth-sized planets are in the universe. The mission observes the incremental decrease in light that occurs when a planet transits in front of its host star, currently considered the most likely way to find Earth analogs. Koch showed current data from Kepler, which has already discovered several Jupiter-sized planets and what may be a planet orbiting around a binary star system.

Finally, meteorologist Jacob Haqq-Misra of Penn State gave a talk about how the biosphere influences our Earth as a whole. Though man-made global warming is a crisis for us humans, Haqq-Misra pointed out that it would likely not be a catastrophe for microbial life. He looked at earlier epochs in the Earth’s history, when the planet was warmer despite the fact that the Sun was less bright. The paradox is explained by the presence of microbes, which pumped greenhouse gases, such as methane and carbon dioxide, into the atmosphere. In contrast, the Earth has also gone through long periods of cold, perhaps even being completely covered in ice. Through all these eras, bacteria thrived. In fact, though there is fossil evidence of mass extinctions of animals and plants, no corresponding bacterial extinctions can be found in the record. Haqq-Misra explained that, when looking for extraterrestrial life, we should consider environments that we think of as very hostile.

–Adam Mann, UC Santa Cruz Science Communication Graduate Student