Europa in a Can

November 12, 2008

Back in 2005, Oscar-winning director James Cameron -- whose Hollywood blockbusters include the first two Terminator movies, True Lies, Aliens, The Abyss, and Titanic -- debuted a lavish, 3D IMAX movie called Aliens of the Deep at science centers and museums across the country. He took his film crew along for the ride when NASA scientists and marine biologists aboard the Russian research vessel Akademik Mstislav Keldysh dove deep into the Atlantic and Pacific Oceans to investigate hydrothermal vents. The Internet Movie Database offers a succinct description of why this is of scientific interest in its plot summary:

"These are violent volcanic regions where new planet is literally being born and where the interaction between ocean and molten rock creates plumes of super-heated, chemically-charged water that serve as oases for animals unlike anything ever discovered. Six-foot tall worms with blood-red plumes and no stomach, blind white crabs, and a biomass of shrimp capable of "seeing" heat all compete to find just the right location in the flow of the super-heated, life-giving water or to fry trying. Not dependent on sunlight (like all other life on earth), these ecosystems are as close to alien as anything ever imagined and provide one possible blueprint for the life that might exist beyond our world."

Hydrothermal vents are found at the spreading ridges between ocean plates. Molten rock oozes through the vents to create new ocean crust, amounting to deep-sea hot springs like those found at Yellowstone National Park. And somehow, living organisms thrive under these harsh conditions, although they are very different from the creatures that thrive elsewhere on Earth.

It's fitting that Cameron's film The Abyss explored the possibility of aliens inhabiting the dark recesses of the ocean depths, because the conditions at the hydrothermal vents are remarkably similar to those found on other planets and their moons -- most notably on Europa, one of the moons of Jupiter. Ergo, the life that thrives at these vents might give scientists a good idea of what to look for as we probe the atmospheres and surface characteristics of these distant worlds.

One of the featured scientists in Cameron's eye-popping IMAX extravaganza is Kevin Hand, a young astrobiologist at Jet Propulsion Lab in Pasadena, California. He was still a grad student when he got the chance to dive two miles down to the ocean depths to collect samples and images of the amazing creatures that somehow thrive in that hostile environment. He's been something of an Explorer for Science ever since. Granted, a large fraction of his research takes place in a lab, but he still travels all over the world for field work, even if oodles of practical considerations prevent him from exploring the distant moons of Jupiter firsthand.

In fact, when we met him for drinks earlier this week, he'd just returned from Africa, where -- among other activities -- he drew on his past mountaineering experience to rappel down the side of Mount Kilmanjaro to collect core samples. It was a low-budget improvisation, since he couldn't afford to bring the JPL-designed robotic probe halfway around the world to do it for him. So, Hand is young (early 30s); smart; successful; single; personable; athletic; and well-traveled. Did I mention his strong social conscience? On top of everything else, he founded a non-profit international group called Cosmos Education, to "inspire, empower, and engage [young African students] to become the future scientists, leaders, teachers of their village, country, Africa, or the world."

Sheesh. I advised him to work on developing a few personal flaws, just so he stops making the rest of us look bad. Anyway, Hand describes the hydrothermal vents he studied as "fantastic cauldrons of interesting chemistry," given the fact that the fluids contain crucial compounds like hydrogen sulfide, pyrite, iron, copper, and zinc. Those and other chemicals, combined with liquid water and the energy from all that volcanic activity, are pretty much prerequisites for the presence of life in the deep sea. They provide a food source of oxidized metals for extremophile microbes, for starters.

And if life can thrive near hydrothermal vents deep in our own ocean, it's possible that similar forms of life might be found within our solar system -- for instance, on Europa, with its thin wisp of an atmosphere, temperatures of -260 degrees Fahrenheit, and thick outer shell of ice that scientists believe covers an ocean more than 60 miles deep. Europa is roughly the size of our own moon, but if this hypothesis proves correct, it has more water than Earth. Comets hitting Europa would deliver the necessary chemical building blocks.

Hand's doctoral thesis research involved exploring the potential for life on Europa, specifically, the physics and chemistry that might come into play, and whether the process contains sufficient energy -- from, say, volcanic activity -- to drive an actual ecosystem. To do this, he recreates the conditions on Europa in a special experimental chamber in his lab -- what he has dubbed "Europa in a can" -- and then introduces various terrestrial microbes into that environment to see what happens. He now has two such chambers, in fact, so that one can serve as a "control" to compare and contrast.

In 2006, University of Colorado space scientist Robert Pappalardo said, "Europa, today, probably is a habitable environment." It's by no means certain, mind you: the point is that Europa appears to have "all the ingredients for life" -- not just for life billions of years ago, but life that could be thriving just beneath its icy surface right now. We just need to spend the cash to find some way of confirming this hypothesis.

So far, all we know about Europa comes from various fly-by missions -- most recently, the Galileo spacecraft, which beamed back some truly stunning images of the icy moon's surface. Ideally, scientists would like to send robotic landers (like the recently deceased Phoenix) to drill through the crust and look for signs of life in the underlying "ocean." That hasn't been NASA's top priority in the last few years, with all eyes focused on Mars and -- further afield -- the Cassini spacecraft currently orbiting Saturn.

But there's a very good chance that NASA will choose to send a satellite or probe to explore Europa, or the entire Jupiter system, as its next flagship mission. And then, I guess, we'll see if alien life really is out there.

Photos: (top) A "black smoker" at a mid-ocean ridge hydrothermal vent in the Atlantic Ocean (P. Rona). Source: U.S. National Oceanic and Atmospheric Administration. (bottom) Europa as seen by the Galileo spacecraft. Source: NASA/Jet Propulsion Lab.