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Tuesday, June 23, 2009

Oceans of Europa: Will the Solar Systems' 1st Extraterrestrial Life be Found There?

Jupiters Europa Jupiter's Europa. One of the most interesting non-Earth locations in the solar system. Never mind ice and occasional puddles, this moon has entire oceans - and where there's water, we can't help but hope there's life. Recent results show that there are heat sources to drive evolution of such as well, but there's still debate over what's actually going on in there.

Europa has been of interest since we started to suspect it hid water under its frozen crust, attracting the interest of everyone from NASA to Arthur C. Clarke. The widely accepted picture has Europa's rocky core stressed by the Jupiter's gravity. Which is a lot, by the way - at two times ten to the power of twenty-seven kilograms, Jupiter is so massive the SI system doesn't even have a prefix that goes that high.

A hidden ocean, sealed under kilometers of ice, far off in space. That image is so utterly calm you might have fallen asleep while reading it (in which case we apologize for stealing hours of your life), and according to Robert Tyler of the University of Washington it's entirely wrong. He's made mathematical models showing that the secret seas are hugely violent bodies thrown around by the immense mass of Jupiter.

Tyler's model, however, has those massive gravitational forces acting on the oceans directly. The result is truly titanic tides, waves so gigantic they make the Titanic itself look like a speck of sand. His models put the minimum kinetic energy of the flow at seven point three exaJoules. In the standard unit for ridiculous amounts of energy, that's one hundred thousand times the atom bomb dropped on Hiroshima, or 100 kiloLittleBoys.

The theory is meeting with some resistance, as papers effectively titled "Everything all y'all were saying up to now was wrong" usually do. We won't know either way until we get a closer look at this most interesting of interplanetary destinations. Until then we know one thing: with a theory that involves incredible undersea upheaval, super-nuclear natural disasters and energy sources for potential alien life, if it turns out he isn't right about the science Prof Tyler can always work with Michael Bay.

The key point of contention is the moon's crunchy ice covering. We know that the Jovian moon is coated in kilometers of frozen material, but that sort of handwaving figure can get you in trouble - exactly how many kilometers there are can make all the difference. We believe that the European core is heated by the massive tidal forces applied by Jupiter - but how does that heat radiate into space?

Most scientists believe that the subEuropan seas are locked under tens of kilometers of ice. Heat is then conducted from the warm core by bulk convective motion of ice - huge chunks of frozen material literally carrying the heat away with them as they move up through the icy layer, shuffling and refreezing as they dump heat into space.

Richard Greenberg, a professor of planetary sciences at the University of Arizona's Lunar and Planetary Laboratory, believes that the crust is thin, only a kilometer or so, and heat is carried out by simple conduction - much slower, but providing a constant flow of energy through a relatively fixed underwater region bordering the immense cliffs of ice.

Greenberg does weaken his case by accusing a "Big Ice" cabal of scientists of suppressing his results, holding back his views to favor their own established model. The thing is, when you start talking about a conspiracy against you it doesn't matter if you're right or wrong: you sound a bit crazy. Especially when that "cabal" isn't a hidden core of ultra-billionaires, but probably about twenty guys with tenure who meet twice a year to talk about space moons.

On the upside, it seems the shadowy Europa lobby can't keep him silent and he's published a book, "Unmasking Europa", putting forward his views and setting up the mother of all "I told you so"s if it turns out he's right. Again, he slightly weakens his case by fantasizing an entire Europan ecosystem based on a few flybys of the Galileo probe, and it's not as if popular opinion will actually sway the scientists investigating the issue.

What is important is that such issues do now percolate to the public, one way or another. Science is no longer the preserve of those either rich enough to afford it or trying to build missiles out of it. Beside the cook books and crime novels you can find imaginings of the stars, controversies of the cosmos, and books about the entire universe. Which are slightly more interesting than "Five things you can do with leftovers" by Dolores Housewife.

Posted by Luke McKinney.

Unmasking Europa

Europa 1 - Titan 0