There's an interesting article at PhysOrg about the possibility of life on Saturn's moon Titan. Since the 1940s humans have known that Titan has an atmosphere rich in complex carbon compounds, and that fueled (heh) speculation about living beings there. Kurt Vonnegut put a civilization there in The Sirens of Titan, and Robert Heinlein made it the home of The Puppet Masters.
As we've learned more about conditions on Titan, our ideas about what might live there have gotten stranger. Life on Titan wouldn't be anything like life on Earth -- water is a rock there, and the lakes are full of liquid methane. In that cold environment life chemistry could be based on chains of hydrocarbons.
The Huygens probe dropped through Titan's murky atmosphere and found a dry surface with no Titanian beings peering back at the camera -- but it didn't land near any of the methane lakes where scientists now want to look for life. At present nobody's planning a new Saturn probe, though there is hope that NASA and the ESA could collaborate on one (possibly a hot-air balloon!) a couple of decades down the road.
Why bother? If looking for life on Mars could teach us something about Earthly life by studying the similarities, looking for life on Titan would teach us what kinds of other life might exist in the universe. It would also give us information on how common life is in the Galaxy -- Earth and Mars are close and similar enough to "infect" each other, but life on Titan would be an entirely separate evolution. That would mean we could expect life to be common in other star systems.
That, of course, brings up the question of the Fermi Paradox -- if life is so common, where are they? Which in turn leads to the idea of the "Great Filter." If life is common and technological civilizations are rare, something must act as a "filter." It would be nice to know if some huge bottleneck is looming in our future ready to filter us out.
So, in short: we should look for life on Titan to find out if something is going to kill us all. Is that important enough?
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