Sunday, December 15, 2013

Water Vapor From Europa's South Pole

PART I: Europa has water vapor plumes at its south poles, consistent with tidal heating (Science paper here.) These are more easily understood but no less exciting than the water vapor plumes seen last year over the south pole of Saturn's moon Enceladus, which turned out to contain organics.


The reason this is so interesting is not just the possibility of life in these alien oceans, but the broader implications for the spread of chemical replicators on water-containing low-gravity bodies. Increasingly it seems that many asteroids are just dried-out comets that last their external volatiles, like we just watched in accelerated fashion with ISON. It's now well-established that both asteroids and comets contain amino acids and nucleobases (PNAS paper there), both from samples of fallen meteors as well as sample return missions like Stardust, which brought back material from comet Wild-2, which turned out to have an extra-solar origin (as well as carrying the amino acid glycine). If there are replicators - either natively evolved, or von Neumann probes, mutant or otherwise - it is likely they'll be composed of easily available building blocks in low gravity environments, and spread during Oort cloud exchange between adjacent solar systems.

Another implication is that the answer to the Fermi paradox may be that we're a little premature in saying there's no evidence of life. This is especially true since humans haven't even made 50 soft landings on other bodies in our own solar system. The Dawn mission to Ceres arrives in 2015 and the findings will be interesting no matter what.

As an aside, replicators that spread between stars would ideally avoid gravity wells like Earth, because we're dead-ends, at least without expending huge amounts of energy to get back out. That said, if you think simple life at the scale of a virus or prokaryote couldn't survive re-entry simply by sheltering in a crack on a rock, try again. The C. elegans worms carried aboard the Columbia were found alive in a Texas swamp 3 weeks after the shuttle broke up on re-entry. And they're multicellular.

(Of note for amateur astronomers: here's a Twitter feed for a quick check of the positions of Jupiter's moons relative to Earth. If it's cold and clear where you live, take advantage and get out there with a telescope!)

PART II: Movie Review, Europa Report

Fittingly enough I watched Europa report about two weeks before this news came out. It's on Netflix, and if you have Netflix, go watch it right now. (Trailer) It's a recently released independent and I'd count it among the better science fiction movies I've seen. A la 2001 and other hard science fiction works, there's not a lot of screwing around with normal filmy conventions; although maybe too much character development for my taste, because character development is not what this film is for. It's a technically accurate, very un-wild-eyed tale about the first manned landing on Europa, told mostly in raw video logs from the spacecraft with occasional after-the-fact narration from the mission chief on the ground. Beyond that I can't tell you too much without spoiling the movie, but you don't need me to. My only criticism, and it's not really a criticism, is that at times I felt like it was made as a trick to get more young people excited about the next phase of space exploration. If that's true, they still made an excellent movie. (Like I said, not a criticism.)

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