Mars has methane, which implies the presence of volcanic or tectonic out-gassing or microbial life. We know Mars has been geologically inactive for hundreds of millions if not billions of years, so that’s leaving the methane looking decidedly like an organic by-product. This is one of the things NASA’s Curiosity Rover is going to investigate when it lands on Mars in 2012.
Methane, or CH4 as it’s known to its friends, is simple molecule, but it cannot survive in the Martian atmosphere for any significant length of time because…
- The lack of a planetary magnetic core leaves it vulnerable to ultraviolet radiation that breaks the molecule apart
- The lack of substantial gravity and lack of protection from solar wind, means the thin Martian atmosphere gets stripped off into space quite easily
It’s interesting to note that micro-organisms, on Earth, at least, produce methane through a simple process known as methanogenesis, an anaerobic reaction (that doesn’t require oxygen). It’s a reaction that’s perfectly suited to the red planet as the principle pathway required for this chemical reaction is carbon dioxide and the result is methane and water. With all three molecular suspects and one element present on Mars, there’s a good case to go looking for bugs.
CO2 + 8 H+ + 8 e– → CH4 + 2 H2O
Methane has also been detected on Titan, although this may be from geological activity.
Titan, on the other hand, has its own peculiar mysteries. Hydrogen, which is abundant in the upper atmosphere, is curiously absent lower down, which implies it has probably been absorbed by something, something that just might be alive.
If this bears out under more scrutiny, it would raise the fascinating prospect that there could be lifeforms using hydrogen as we use oxygen.
If Mars and Titan both have life, and I know it’s a big ask, but if they do, then we would have the remarkable prospect of living in a solar system that has three habitable environments and two, possibly three, distinctly different types of lifeforms. If that turns out to be the case, then the prospect of finding life elsewhere in the universe, and possibility of there being intelligent extraterrestrial life, would leap up exponentially.
Now, there’s plenty of other avenues for methane production to consider before the champagne corks get popped, but what a tantalising possibility. These are exciting times in which we live.
I’m intensely curious about what Curiosity will uncover on the red planet, aren’t you?