STEVE INSKEEP, host:
Now, it may feel like Antarctica across much of the United States, but at least our ice is not two miles thick. Russian scientists have been drilling in a spot near the South Pole where the ice is that thick and they are close to breaking through to something extraordinary - a vast Antarctic lake, liquid water under all that ice.
If the Russians break through, they may tap into a primitive ecosystem that's been undisturbed down there for millions of years. Of course that might not be a good thing for the ecosystem. NPR's Richard Harris reports.
RICHARD HARRIS: Lake Vostok is actually the third largest lake in the world, measured by the amount of water it holds. And if you're surprised to learn that there could be a vast pool of liquid water under two miles of ice, so were the Soviets. In fact, they had no idea there was a lake there when they built a camp at Vostok, Antarctica more than 50 years ago.
Robin Bell from the Lamont-Doherty Earth Observatory says the Soviets picked the spot because it was the earth's magnetic South Pole.
Professor ROBIN BELL (Senior Research Scientist, Lamont-Doherty Earth Observatory): The Russians went to the magnetic South Pole in 1958 because they missed the race to the rotational South Pole.
HARRIS: The U.S. claimed that prime real estate. And it turns out the south magnetic pole isn't fixed in one place. In fact, it wandered off from Camp Vostok, leaving the Soviet base seemingly in the middle of nowhere.
Undaunted, the Russians drilled down through the ice at their feet to sample tiny air bubbles trapped inside. And in the early 1990s, they recreated a history of the Earth's atmosphere throughout the last 400,000 years.
Bell says the hole they drilled was more than two miles deep.
Prof. BELL: When they got to the bottom, they suddenly found this ice that didn't seem to be the same - giant crystals, it was a different acidity, and there were no gas bubbles in it.
HARRIS: Gradually, scientists realized that this odd layer of ice was actually from the roof of an enormous lake, buried directly beneath them.
Prof. BELL: And right about then, the satellite imagery came out, and you could see this area the size of New Jersey was in dead flat, and there was a lake.
HARRIS: Ever since, Russians have been dying to complete their hole into the lake.
Prof. BELL: So the real question is: Is there life in Lake Vostok?
HARRIS: And if there is, how old would it be?
Prof. BELL: Well, as I like to think of it, this lake hasn't had the wind blow across it for maybe 35 million years, but the water has changed every tens of thousands of years. So the water is relatively new. The lake is old.
HARRIS: But getting a sample was no simple matter. It took Russian scientists more than a decade to come up with an acceptable plan for drilling into the lake without disturbing it. They started drilling down again in early January.
Jim Barnes has been watching this process closely, as head of a non-governmental organization called the Antarctic and Southern Ocean Coalition.
Mr. JIM BARNES (Executive Director, Antarctic and Southern Ocean Coalition): Well, to be perfectly honest, we are not very happy about it.
HARRIS: Of major concern is the Russians have filled the hole they're drilling with more than 14,000 gallons of kerosene and Freon, in order to prevent it from freezing shut. The Russians have engineered their system so that when they break through into the lake, water pressure from below is supposed to push the drilling fluids up the hole, rather than letting them pour into the lake and contaminating it. But Barnes is nervous.
Mr. BARNES: Nobody needs to go into this particular lake, or any particular lake, tomorrow. There's no driving need for it. Why take risks that are unnecessary?
HARRIS: Another worry is that the lake water could come rushing up the hole.
John Priscu from Montana State University says the water in the lake is gassy, and if the Russians aren't careful, the lake water could spew out like a shaken bottle of soda.
Professor JOHN PRISCU (Department of Land Resources and Environmental Sciences, Montana State University): That would be a very bad thing if they did it. You'd geyser out through the top, and you would drain the lake into the atmosphere. I mean there's 5,400 cubic kilometers of water in that lake.
HARRIS: So you think it would all come out?
Prof. PRISCU: A lot. Yeah, it would just keep blasting out until it degassed.
HARRIS: Priscu isn't expecting a disaster. But if there is one, he says it could set back plans by U.S. scientists, including himself, and British scientists to drill into two other buried Antarctic lakes in the coming years.
Robin Bell from Lamont-Doherty says it's a matter of Russian pride to get this right.
Prof. BELL: They didn't get to the Moon first. They really, really want to be the first people to drill into a sub-glacial lake. And they want to do it right.
HARRIS: And this story, for now, is probably going to end as a cliffhanger. The head of the Russian program told NPR on Wednesday that they have about 100 feet left to drill. But this cold place is about to turn even colder, as the seasons change, so the drilling crew needs to fly out on Sunday and they're unlikely to be done by then.
Richard Harris, NPR News.