Space pioneer: The ENDURANCE robot will dive to the bottom of an Antarctic lake this month. Such tests fuel research into future space-based robots that could one day explore oceans on other planets.
Credit: John Rummel, NASA
In May, 2007, working under the name Clementine, it reached the base of El Zacaton, a 319-metre sinkhole in Mexico's Yucatan Peninsula – too deep for any human cave diver to have found the bottom and survived. In addition to mapping the cave, Clementine took water measurements and scraped previously unknown bacteria from the walls, all while out of contact with its operators.
Then, in February 2008, it was tested under-ice in a frozen lake near Madison, Wisconsin, in the USA. It found its way back, and demonstrated that its electronics functioned perfectly well in cold water.
At Lake Bonney, ENDURANCE will not only map the lake and explore its biology, but also take a close look at the base of a feature called Blood Falls, where reddish, iron-containing salts spill out of the face of a glacier at the lake's upper end.
Probing a mystery
But while there's much to learn from Lake Bonney, all eyes are fixed on an even larger goal. Someday, Stone's crew hopes, ENDURANCE's robotic descendents will unlock the secrets of Lake Vostok, one of the world's largest, deepest, and most mysterious lakes.
Lake Vostok is also in Antarctica, but it's beneath 3.5 km of ice. It first came to light in the 1970s, when researchers noticed odd radar echoes bouncing off the bottom.
"Ice is transparent to radar at frequencies of megahertz," says Donald Blankenship, a University of Texas researcher who hopes someday to use radar to peer through the crust of Jupiter's icy moon Europa, also believed to have water beneath its surface.
But the radar of the '70s was primitive, and nobody was quite sure what was being seen. Then, in 1996, airborne and space-borne instruments were able to take a more detailed look.
What they found was an enormous body of water – approximately the size of America's Lake Ontario and hundreds of metres deep. Since then, about 140 more sub-glacial lakes have been found, but Vostok remains the largest.
Extreme life
Particularly interesting is the question of whether the lake might contain a functioning ecosystem.
By the 1990s, scientists had been finding life in the oddest of places: inside rocks, deep beneath the sea near hydrothermal vents – places seemingly cut off from the normal processes of the outside world.
But it wasn't clear how to peek into the lake without contaminating it, either with drilling fluids or microbes carried down from the surface.
Early drilling efforts were discontinued as too risky and, due to ongoing controversy, are still postponed. According to a recent report in Nature, the Russians will wait until at least 2009 to 2010 before attempting to reach into the lake.
