Antarctic lake drilling gets cleaner, more advanced
Lake Whillans lies underneath a wide and fast-moving ice stream embedded in the Antarctic ice sheet.
Mon, Jan 28, 2013 at 10:42 AM
Lake Whillans drilling base camp (Photo: WISSARD Project)
U.S. scientists successfully drilled into Lake Whillans, a subglacial expanse of water hidden deep beneath the Antarctic ice sheet, they reported on Jan. 27.
About a month ago, a similar British attempt to reach subglacial Lake Ellsworth had failed. Drilling operations for the WISSARD project (Whillans Ice Stream Subglacial Access Research Drilling), which is funded by the U.S. National Science Foundation's Office of Polar Programs, started on Jan. 21.
Over the next couple of days, equipment will be lowered down the 2,625-foot (800-meter)-deep hole to carry out measurements and to obtain water samples for further study on board container-based scientific laboratories on the surface. As of Sunday (Jan. 27), the WISSARD team said they may have penetrated the lake surface.
"Sensors on the hot water drill show a water pressure change, indicating that the borehole has connected with the lake," they write on the WISSARD blog. "Verification awaits visual images from a down-borehole camera this evening. We are excited about the latest developments at the lake!" [See Photos of Subglacial Lake Whillans Drilling Site]
The bottom of the world
On Dec. 9, I visited the WISSARD test site on the Ross Ice Shelf, just off the coast of the Antarctic continent and close to McMurdo Station, as a selected member of the NSF Antarctic media visit program. The test site resembled a small factory, with generators, water tanks, labs, workshops, data centers and, of course, the actual drilling platform – all mounted on giant skis. In the background were the tractors that would pull the whole installation to Lake Whillans, across hundreds of miles of solid ice.
"This is a first go," said Ross Powell of the University of Northern Illinois, one of WISSARD's 13 principal investigators. "Next year we hope to return to drill more holes."
Frank Rack, a geologic oceanographer of the University of Nebraska who leads the WISSARD drill team, explained how a powerful jet of pressurized hot water is used to melt a hole in the ice.
"Our hot water drill is state-of-the-art," Rack said. Part of the system, including two 225-kilowatt generators and the power distribution modules, had previously been used to drill the holes for the IceCube Neutrino Observatory at the South Pole. The technique is simple in principle, but prone to unexpected problems. "My biggest worry is that something might get stuck," Powell said. With the successful completion of the actual drilling at Lake Whillans, this worry has now been laid to rest.
A big concern for the WISSARD team has been to prevent contamination of samples from the subglacial lake with microorganisms. After all, an important goal of the project is studying the lake's ecosystem, if it exists at all. Even at 195 degrees Fahrenheit (90 degrees Celsius) — the temperature the pressurized water for drilling is heated to — water contains a lot of spore-forming bacteria. That’s why the drilling hose is fed through a collar of ultraviolet lamps: the energetic radiation kills 99.9 percent of all microorganisms.
In contrast, the Russian team that drilled into subglacial Lake Vostok last year used kerosene to lubricate the borehole – a technique significantly less clean than hot-water-drilling.
Microbiologist Jill Mikucki of the University of Tennessee is pretty sure there might be life under the ice: microorganisms that are able to thrive in the cold, dark, isolated subglacial lakes. She doesn't expect to encounter larger organisms, because there's so little energy available at 2,625 feet (800 m) below the icecap, but "microbes are everywhere," Mikucki said. "There's even potential to find new species."
Subglacial microbes could accelerate weathering of rocks, Mikucki explained, releasing silicon and iron that finds its way into the ocean and serves as nutrients for other life forms. "I want to find out how they help to run the planet." [Antarctica Album: Stunning Photos of IceBridge Mission]
Meanwhile, geologists and glaciologists are eager to learn more about water transport and ice dynamics beneath the frozen Antarctic surface. Lake Whillans lies beneath a 66-foot (20-meter) wide ice stream that moves about a meter per day, as opposed to something like a meter per year for the surrounding icecap. Little is known about the possible relation between ice streams on the surface and subglacial river systems, which have only been discovered — and charted through radar — over the past couple of decades.
"Lake Whillans is just one of a few hundred interconnected lakes," said Powell, "and radar observations have revealed that it fills and drains in a five-to-10-year cycle. We want to find out what causes these cycles. And knowing more about ice dynamics is important to better understand the effects global warming might have on the Antarctic continent. Thanks to WISSARD, we will be able for the first time to use real field data as input in our glacialogical models."
Even the 66-foot (80-m)-deep test drill through the Ross Ice Shelf, completed in mid-December, was of interest to scientists. An earlier program called ANDRILL (for Antarctic Drilling project), also led by Rack, encountered some unusual life forms beneath the ice, including giant anemones and previously unknown organisms looking like floating spring rolls. "Pretty surprising," Rack said. "I have a museum guy doing the taxonomy right now, and we are writing it up for Science magazine. At the WISSARD test site we could find similar — or very different — organisms. We'll have to see.” Results from the test drilling have not yet been released. [Life on Ice: Gallery of Cold-Loving Creatures]
Planetary scientist Britney Schmidt of the University of Texas at Austin has deployed a small, tethered robotic submersible through the test borehole. Known as SCINI (Submersible Capable of under Ice Navigation and Imaging), it is outfitted with a lamp and a camera. "It looks for everything under the ice," Schmidt told me at her temporary office at McMurdo Station. "There's no reason that I could think of why we would not find interesting organisms."
In the future, Schmidt hopes to use similar techniques to search for life in the subglacial ocean of Europa, one of the four large satellites of Jupiter. "I'm not 100 percent sure that there is life on Europa," she said, "but if it’s not there, I'd like to learn why it isn't there." Again, the SCINI results from the test site are not yet published, but it's clear that projects like WISSARD are already firing the imagination of planetary scientists and astrobiologists.
It will be a while before scientists succeed in drilling through the polar ice of Mars, or through the icy crust of Europa, but the success at Lake Whillans gives them a taste of things to come. Meanwhile, WISSARD will provide geochemists and microbiologists alike with a unique picture of an integrated subglacial ecosystem. "Other systems are much easier to study," said Mikucki, "but from Antarctica we only have limited samples so far. Since 10 percent of the Earth's land surface is covered with ice, we really need more data to understand our planet. Antarctica is an important piece of the puzzle."
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