Wednesday, June 9, 2010

Titan as seen from Cassini: an abode of life?

Recent discoveries about Titan, Saturn's largest moon, have led to increased speculation that we may not be alone in the universe. All of the new findings come courtesy of the Cassini spacecraft, launched on its mission to Saturn and Titan over five years ago.

The discovery? An unexpected absence of hydrogen on Titan's surface. The implications: anything from life to natural processes. Life first.

The findings concerning hydrogen on Titan are interesting to say the least. First, hydrogen has been detected high up in Titan's atmosphere. However, as one gets closer to the surface of the moon, hydrogen decreases. So where is it all going? One possibility is that it is being used by living organisms.

So far as we know, all life requires liquid in some form. On Titan, it is far too cold (-290 degrees Fahrenheit) for any life to use water. However, liquid methane lakes have been detected on Titan. Now, this is an educated guess, but it is possible. Models for methane-based (rather than carbon based) life have been proposed. Now think about it: humans use oxygen to breathe. The human body is also made up, in large part, of oxygen, as the human body is mostly water. Now if life on Titan follows a similar path, it is very possible that methane-based life would use part of the methane molecule (the hydrogen) for respiration.

Now the other possibilities.

Some unknown chemical reaction could be going on that converts bare hydrogen into something else, such as methane. Sunlight reacting with chemicals on Titan could be doing something to make the hydrogen form into something else in the atmosphere. In short, there are a lot of possible chemical reactions going on that could account for the unexpected absence of hydrogen.

When searching for life on other worlds, there are a lot of things that can give false positives. What scientists need to look for is some life-hinting signature that cannot explained by any natural phenomenon.

Stay tuned.

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