Sunday, January 15, 2012

Looking For Life on Titan

For my final life on other worlds themed entry, no really, I promise, I have saved my favorite object within our own solar system, for last. And if for some reason it strikes as odd that I might actually have a favorite such object, well then you've clearly underestimated just how much of a geek I truly am. The alien world to which I am referring in this case is Saturn's sixth moon, Titan. Which, if you're unfamiliar, is an amazing place.

False color image of Titan's Sea of Ligeia

Like most objects in the outer solar system, Titan is a frigid place, one where surface temperatures regularly dip down to a frosty -300 degrees F. But unlike any other known planetary satellite, Titan is veiled in a thick atmosphere, a soupy, haze of methane and nitrogen that allows for the formation of, amongst other things, weather patterns. Titan's atmosphere is so dense, in fact, that it effectively shielded the moon's surface from the view of probes until the arrival of the Cassini spacecraft and it's companion Hyugens lander, in 2004. The data and images Cassini collected, as well as the images hyugens managed to return during its brief life on Titan's surface, revealed what is without a doubt the most spectacular and Earth-like features of Titan- standing lakes, rivers, and even seas, of what is believed to be liquid methane and ethane, and a landscape which seemed to bear clear evidence of liquid erosion.

It goes without saying, that there are obviously major fundamental differences between our own world and Titan, but the more we learn about it, the clearer it becomes that this distant moon really is, in many ways, a mirror-image of Earth. Which is why some scientists have begun to speculate that if so many other processes could be mirrored using alternative chemistry -such as methane and ethane taking the place of water in it's weather cycle- why couldn't life do the same?

To be clear, there is as of yet no confirmed evidence of life of any form on this distant moon. But several papers analyzing data collected by the Cassini craft emerged last year, which described the seeming disappearance of hydrogen from the moon's atmosphere, as well as a lack of acetylene on it's surface. Theories have suggested that methane-based life, if it were to exist, would likely consume both hydrogen and acetylene as part of it's natural biological process. Such a methanogenic life form is, of course, entirely theoretical at this point, and some as of yet unidentified chemical process is much more likely to proven as the ultimate source of the missing materials. But, as always, there remains a chance that these apparent chemical anomalies could be the sign of an entirely new form of life, on a world some 890 million miles away from our own.

Though all suggestion of life on any world other than our own remains entirely speculative at this point, Titan, along with all the other worlds I have mentioned in this series of entries, are just a few of the known places, even within our own solar system, that could potentially serve as home for some basic form of life. And with the continued discovery of exoplanets orbiting in the habitable zones of distant stars and even the still fairly recent revelation that oxygen and water are far more abundant on other worlds than was previously believed, the notion that life too -basic life anyway, intelligent life is a whole other story- will eventually prove to be equally common place, seems a reasonable conclusion. For now of course, we'll all just have to wait and see.


Image credit: NASA/JPL

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