Astrobiology: The Search for Life on Mars
by azmanam on Feb 26 2010 (10481 Views)
Photo: Techchee.com
(for other entries in the Chemistry in Space series, click here)
This doesn't exactly fit in with the direction I was planning on taking with the posts on space science, but a story on MSNBC.com on Wednesday got my attention. The story discusses NASA's long endeavor into the search for life outside of Earth. It used to be called exobiology (which I find to be an awesome name), but is now referred to as astrobiology.
NASA has previously attempted to find life on Mars with the Viking program in the 1970s. Probes were sent to Mars to look for life... Earth life, that is. The tests the probes ran attempted to find life that would exist at physiological conditions on Earth, a supposition that perhaps seems silly in hindsight.
An option in line with NASA's recent change in direction could have the potential to bring Martian samples back to Earth for another attempt to find life on Mars. The program - still in theoretical infancy - would last some 3-4 years and could begin in 2018 with sending a joint US/European rover to Mars to collect samples. In 2020, a return vessel would go to Mars, get the samples, and return.
The story talks about the potential hazards of bring unknown astrobiological samples to Earth and the need to handle them in the equivalent of a Biosafety Level 4 Lab.
Anyway, my point in bringing this up is to share with you a short story - a commentary, really - by one of my favorite science fiction writers ever: Isaac Asmiov. Asimov (also a former biochemist at Boston University) developed the Three Laws of Robotics and is the author of the original robot series that inspired movies such as I, Robot and Bicentennial Man. If you haven't read any of his work, I highly recommend one of his collections of short stories, such as The Complete Robot.
The commentary you should read is titled "Not as We Know It: The Chemistry of Life" and outlines what NASA scientists should keep in mind: life outside of Earth probably won't look like life on Earth.
(in talking about life on Jupiter): An objection that might, however, be raised against the whole concept of an ammonia background for life, rests on the fact that living organisms are made up of unstable compounds that react quickly, subtly and variously. The proteins that are so characteristic of life-as-we-know-it must consequently be on the edge of instability. A slight rise in temperature and they break down.
A drop in temperature, on the other hand, might make protein molecules too stable. At temperatures near the freezing point of water, many forms of non-warm-blooded life become sluggish indeed. In an ammonia environment with temperatures that are a hundred or so Centigrade degrees lower than the freezing point of water, would not chemical reactions become too slow to support life?
The answer is twofold. In the first place, why is "slow" to be considered "too slow?" Why might there not be forms of life that live at slow motion compared to ourselves? Plants do.
He continues on to describe, in his opinion, what life might look like under the natural conditions of the various planets. What the background medium would have to be and what the life-sustaining molecules would have to look like. A fascinating read and a must read, in my opinion.
