Explorers seeking signs under Anatarctica
BY JAMES GORMAN
NEW YORK -- Three major scientific projects set out this season to seek evidence of life in lakes deep under the Antarctic ice — evidence that could provide clues in the search for evidence of life elsewhere in the solar system, perhaps in Mars’s past, or even now under the surface of Enceladus, one of Saturn’s moons. But only one of the projects, a $10 million expedition from the United States, has a chance of identifying long-hidden microbes before the weather on the frigid continent puts an end to drilling in about a month.
One of the projects, a British effort, ran into technical trouble and had to be called off for this season. An expedition from Russia will be returning samples to be analyzed later.
The American effort, financed by three federal agencies and a private foundation, is about to start drilling into a lake half a mile below a glacier called the Whillans Ice Stream and will analyze samples on the spot in a field laboratory. An announcement of what it finds could come in the next few weeks.
John C. Priscu of Montana State University, a leader of the project, said there was no guarantee. “We don’t know; there are going to be surprises,” he said in a conference call in December with the two other members of the project’s executive committee, Ross D. Powell of Northern Illinois University, and Slawek Tulaczyk of the University of California, Santa Cruz. Dr. Priscu and Dr. Tulaczyk were getting ready to fly to Antarctica; Dr. Powell was already at McMurdo Station, the American scientific base there.
Dr. Priscu is hopeful, he said, given that “10 years of circumstantial evidence” suggest that “there should be a viable microbial community that’s living in the dark and the cold.” The project is called Wissard, for Whillans Ice Stream Subglacial Access Research Drilling.
Both the Russian and British projects aimed to reach waters under two or more miles of ice. Lake Whillans lies under a half-mile of ice. For all three, there is no sun to power living cells, only minerals and heat from the earth’s interior. While life is known to survive in the deep ocean without photosynthesis, nothing like these cold, freshwater depths have ever been explored. Robin Bell, a senior research scientist at Columbia University’s Lamont-Doherty Earth Observatory, who studies the behavior of ice sheets with radar and other techniques, said the subglacial Antarctic lakes hold “whole ecosystems that have never really been looked at.”
Chris McKay, an astrobiologist at NASA Ames Research Center, said that exploring extreme environments offered practical lessons for efforts on other planets, “learning how to make measurements in places where there’s not much life.” And, he said, of the possible candidates for past or present microbial life in the solar system, “none of them have environments near the surface that are habitable.”
The Lake Whillans research is also aimed at understanding the flow of water beneath glaciers into the Southern Ocean and the rate of melting of Antarctic ice, which could provide important information for climate studies.
The Russian project, at Lake Vostok, breached its surface last February after a decade of struggling to get through more than two miles of ice to water that had been sealed away for millions of years. That was at the very end of the Antarctic field season, and weather at Vostok, the site of the coldest temperature ever recorded on Earth (minus 128.6 Fahrenheit), forced a quick departure.
The Russians are back at Lake Vostok this year to retrieve samples of the water that flowed from the surface of the lake up the drill’s bore hole, but they will not know what they have until they return with it to Russia for analysis there. One limitation of the project is that the samples are from only one spot on the surface of a body of water that is the size of Lake Ontario.
The British project also intended to retrieve water samples for later studies, from another, smaller body of water, Lake Ellsworth. But researchers called off that attempt on Christmas Day because the drilling process ran into difficulty at about a thousand feet. The water they had hoped to reach lay almost two miles deep.
The American project is different in several ways. Lake Whillans is smaller and not as deep, and is replenished more quickly from other water sources under the Antarctic ice shelf. It is a basin in a subglacial river where water accumulates to form a lake but keeps flowing, eventually reaching the ocean.
Dr. Priscu said that while the water in Lake Vostok was replaced about every 10,000 years, and the water in Lake Ellsworth every 700 years or so, the replacement rate for Lake Whillans was more on the order of a decade.
The scientific approach is different as well. The Wissard project involves the use of a remote torpedo-shaped submersible, about two and a half feet long. It will operate on a tether about a mile long and will be used to map the three-dimensional space of the underground lake, including its inlets and outlets. Dr. Tulaczyk said that understanding the shape of the lake, and how the water moves in and out, is important for knowing how and why the glaciers above these deep lakes move, “why parts of Antarctica are gaining, and others losing” ice cover.
Glaciologists have a good understanding of how the ice sheets on the surface of Antarctica move, he said, but the nearly 400 known buried lakes affect the movement of ice above them. They can serve as a kind of lubricant between the mountains and valleys of the Antarctic continent’s land mass, and the vast amounts of ice under which it is buried.
The Wissard team will also be taking samples from the sediments at the bottom of the lake, to look for living microbes or chemical evidence of past activity. Subglacial microbes may, for instance, be changing the mineral composition of the water, freeing iron that then flows into the ocean around Antarctica. Of the variety of approaches the team is taking, Dr. Bell said, “If you’re going to pop a hole through an ice sheet like this, you want to do everything you can.”
The project involved not only developing and testing a hot-water drill with a filtering system to prevent contamination of the buried lake, but transporting the drill — along with the submersible and a laboratory capable of on-site analysis of water and sediment samples — over 500 miles of ice, from McMurdo Station to the Lake Whillans site. Thirteen tractors hauled the equipment from the McMurdo research station over the course of two weeks, arriving at the site on Jan. 12.
Speaking from McMurdo on Sunday morning (McMurdo is 18 hours ahead of New York), Dr. Priscu said flights were planned over the next few days to bring the scientists, drillers and other team members out to the field site. By Jan. 21, when he hopes drilling will begin, there will be about 50 people at the camp.
The cold has not posed any logistical problems so far. Instead, unseasonably warm weather has left the runways so mushy that wheeled airplanes cannot take off. Dr. Priscu said planes that land and take off on skis could be used.
The New York Times