Many of the sounding flights passed near the Vostok base—when flying over the featureless landscape, pilots liked using the Soviet flagpole and radio mast to orient themselves—and the “water reflections” recorded there suggested the presence of a particularly large subglacial lake. But not much was made of all this; scientists at the time were less interested in water than in the ice thickness. “People chatted,” Priscu says. “No one took it seriously.”

Their chat turned more serious in 1994, when images from the European ERS-1 satellites were added to the earlier radio-echo soundings and even earlier seismic readings. What had been thought to be frozen sediment on the seismograms was pronounced to be water, and thus it was officially confirmed that beneath Vostok Station lies a huge lake, smaller in area than Lake Ontario but with more than three times the volume. Reviewing the surveys from all the sources, Martin Siegert—then a graduate student, now head of the school of geosciences at the University of Edinburgh—counted 76 lakes besides Vostok scattered around the continent. Also in the mid-1990s, another group of scientists proposed the now widely accepted mechanism for how lakes can form under glaciers: Heat radiating from Earth’s interior is trapped under the thick, insulating ice sheet, and pressure from the weight of all the ice above it lowers the melting point of the ice at the bottom.

The Soviets chose the site for Vostok Station because the ice there is thicker than anywhere else in the world—12,280 feet—and they needed thick ice. They planned to drill out ice cores to study past climates. Ice keeps a record of environmental changes as it accumulates over thousands of years, so the longer the core, the better. Soviet researchers also planned to keep the base operating year-round, even in the deep cold and dark of winter. In his account of the drilling, Russian physicist Igor A. Zotikov often invokes Murphy’s Law. Drills got stuck, pumps failed, boreholes closed. It took 30 years for the men to drill a borehole to the bottom of the ice. But over the years, first as Soviets, then as Russians, and sometimes with help from non-­Russians, Zotikov and his colleagues extracted several useful ice cores, including a landmark one that held 420,000 years of climate data, through four full ice age cycles.

In 1998, while boring near the bottom of that long core, expecting to hit bedrock, the drillers brought up ice with crystals that were startlingly different from those usually found in glacial ice. The crystals were large, for one thing, some of them three feet long. Apparently the drillers had hit meltwater from the top of Lake Vostok that had slowly refrozen and accreted onto the bottom of the overlying glacial ice sheet. After taking out 275 feet of it, the Russians stopped drilling, leaving another 150 feet of ice as a barrier to the lake in case drill and fuel contaminants should leak downward. “We can think of the Vostok drill as a 65-ton enrichment culture,” says Brent Christner, a microbiologist at Louisiana State University. “I wouldn’t be surprised if there wasn’t a booger on it.”

The Russians shared samples of the accreted ice with their French and American collaborators, who came up with wildly contrasting findings. After removing the outside (presumably contaminated) parts of their samples, all the researchers cleaned and melted the (presumably uncontaminated) center ice and looked for signs of microbial life. Working in separate labs, Americans David M. Karl at the University of Hawaii at Honolulu and Priscu found strong signs; both detected hundreds, in some cases thousands, of bacterial cells per milliliter of ice. Some of the bacteria had intact membranes, so “they were alive fairly recently,” Priscu says. They concluded that Lake Vostok may support a viable population of microbes.

In contrast, Sergey Bulat, a molecular biologist at Petersburg Nuclear Physics Institute in Russia, and his French colleague Jean-Robert Petit, a glaciologist at the University of Grenoble (and lead author of the classic paper on the 420,000-year Vostok climate record), detected only a few cells per milliliter; in some specimens they found none at all. The ice was essentially “germ free.” One difference might have been in the samples: “It’s not like a mammoth bone where you saw it in half,” says Christner, a former student of Priscu’s. “Every centimeter of accreted ice represents a different zone of the lake.” More likely, the reason for the conflicting results was a difference in lab techniques. Resolution has to wait until biologists get hold of samples of the Lake Vostok water itself. There was one life-form that Petit and Bulat did consider a plausible lake resident: a thermophile, or heat-loving microbe. In the Vostok core sample, they found a DNA sequence related to a bacterium that thrives in hot springs, like those in Yellowstone Park. Hot spots under the cold of Lake Vostok, they suggested, could come from deep tectonic faults in its bed.

The Russians held off drilling into the accreted ice for seven years, while they went through the long process of preparing a comprehensive environmental evaluation detailing their drilling plans and inviting comment, as required by the Antarctic Treaty, an environmental-protection agreement signed by nations with a presence in the Antarctic. (The treaty is unenforceable, of course; Antarctica has no army.) They also held a competition for the cleanest method for drilling into the lake. The winner was a thermal drill, which uses heated water to melt the ice, and would replace the mechanical one when the team gets close to water. The quantity of drill fluid would then be reduced, causing denser underlying water to flood upward into the borehole and freeze there, forming a plug. “It should work, if they do everything correctly,” Priscu says.

Vostok is the best-known subglacial lake and probably the largest that will ever be found, but there are plenty of others, and satellite and radar surveys keep turning up more. Recently, Siegert updated the inventory and came up with 155 lakes. “There are probably hundreds of them,” he says. “Much of the continent is unsurveyed.” In one area, so many lakes are clustered that Antarctic researchers call it the Lake District. The total amount of water in all these lakes, according to Priscu, is 10 percent of what’s in all the surface lakes of the world. Another way to look at it: The volume of water in all subglacial lakes combined would be enough to cover the entire Antarctic continent to a depth of three feet.

Since the discovery of Lake Vostok and the first explorations of its microbiology, international meetings have been held regularly so scientists can share information and make plans. The most recent meeting, organized by SALE, took place this spring in Big Sky, Montana. Ten countries participated, including, for the first time, Japan.

Valery Lukin of Russia, sporting a gray, Lenin-style goatee, brought everybody up to date on the drilling that had resumed at Vostok. “We had a very interesting season last year,” he reported. “We got 27 meters [90 feet] of new ice.” But in January this year, they suffered a setback. “Our drill jammed in the bottom of the borehole,” he said. “The cable snapped. It was a very serious problem for the Russian Antarctic Expedition.” By the time of the Big Sky meeting, however, the “drilling masters” had recovered the drill with a hook and were once again bringing up ice. Next year, they should bring up more ice, and then in 2009, “using Russian technology,” Lukin said, “we will have ice penetration to the water body.” Tapping his chest with his fingertips repeatedly, he added, “we hope, we hope.”

There seemed to be a sense among the SALE scientists that even if there is a risk of the lake’s being polluted—the new equipment hadn’t been field-tested, for instance—nothing can be done now to stop the Russian plan. “They will go,” Petit remarked during a coffee break. “They are doing what they wish. It’s not an international decision but a national one. Even with dirty hands, they want to be the first.”

While the Russians were rushing in, U.S. agencies were standing back. In Lukin’s opinion that’s because Americans realize they cannot be first to reach a subglacial lake, and, he says, “they don’t like to be second, in any activity.” Actually, the Americans were standing back out of caution. “The bugaboo holding things up has been: How clean is clean?” explains Peter T. Doran, an earth scientist at the University of Illinois at Chicago. Doran had been invited to Big Sky to present a new National Academies of Science/National Research Council (NRC) report (pdf) setting standards for good environmental stewardship in the study of subglacial environments. Unlike space probes, which pass through sterile space, ice drills must pass through thousands of feet of glacial ice loaded with microbes before they reach their target; therefore a microbial buildup on equipment and drilling fluids is “inevitable.” Accepting imperfection, one of the NRC’s recommendations is that the number of cells added to the lake during drilling not exceed the “minimum concentration” of microbes in the glacial ice just above it.

Another NRC recommendation is that projects be multinational. “We don’t want everybody popping their own holes,” Doran says. Scientists want to explore several different lakes because they are in various settings, are of different sizes, and maybe have different ages and origins; all of this suggests each may have its own unique set of life-forms. Probably the next hole to be drilled after Vostok will be into Lake Ellsworth, a small lake in the middle of the West Antarctic ice sheet, with seven countries represented on the British-led team. “Ellsworth is easier to get into than Vostok,” Siegert says. “It’s small and comprehensible. The simpler, the better. We’ll figure it out in one season.” The team doesn’t expect to reach the lake until 2012. None of them thinks it means they have lost a race.

Some of the most unexpected findings presented at the Big Sky sessions described the dynamic effect of the water beneath Antarctica’s ice. Robin Bell, a geophysicist at the Lamont-Doherty Earth Observatory at Columbia University, reported on satellite images indicating that a region of four subglacial lakes at the head of a glacier had initiated an ice stream, a fast-moving feature within an ice sheet that carries ice to the sea. The ordinary meter-or-two-a-year speed of the glacier’s flow increased roughly tenfold as it passed over the lakes. Subglacial lakes are affecting ice sheets, it seems, not just the other way around. “Water is turning out to be the grease that makes the whole system work,” Kennicutt says. “It’s an important player in many processes fundamental to Antarctica.”

Frank Pattyn, a Belgian glaciologist who jokingly wished for a removable ice lid to make lake study easier, mentioned in his presentation other evidence that lake water beneath the glacier moves—far, often, and a lot at a time. When Duncan J. Wingham and his colleagues from University College London reviewed archived satellite records, they noticed that over a period of 16 months, the surface above an unnamed subglacial lake in the center of the East Antarctic ice sheet was sinking. The researchers interpreted the sink (pdf) as the lake discharging water, which it did at a prodigious rate, equal to three-quarters the flow of the Thames River. The water from the first lake spilled into a couple of smaller ones, which themselves drained.

“It’s quite intriguing that these lakes can drain,” Pattyn says. Such sudden flows are probably common events, with feedbacks allowing for drainage “on decadal timescales.” It’s possible that the entire subglacial watershed may be regularly flushed. “At first we thought the lakes were crucibles, museums for ancient life,” Bell says. “They formed 35 million years ago and didn’t change.” Now it’s known that they are not isolated and can change rapidly. Still, any life-forms that may exist in the lakes could have spent millions of years somewhere in the watery network, enough time for them to develop, as Priscu puts it, “some interesting strains.” In other words, there may be life-forms down there that have never existed anywhere else on Earth.

On a day in early June, it started to snow at Big Sky. Several large, brave, warm-blooded organisms from the SALE meeting jumped into the outdoor hot pool and drank beer as the flakes came down. It was a (far-fetched) analogue of what they find in their professional lives engrossing and significant: pools of meltwater under the ice.