St Petersburg

Lake Vostok lies thousands of metres below Vostok Station, the coldest recorded place on Earth. Credit: RIA NOVOSTI/SPL

Russia is postponing its controversial plans to drill into Antarctica's sub-glacial Lake Vostok. Russian scientists now hope to start probing the pristine environment almost 4,000 metres below the East Antarctic ice sheet in the 2009–10 drilling season.

“For technical and legal reasons, penetration is not yet possible this coming season,” Valery Lukin, director of the Russian Antarctic Expedition, told Nature last week at a meeting in St Petersburg of the Scientific Committee on Antarctic Research (SCAR).

Drilling, which got stuck last year in the accretion ice — lake water frozen onto the bottom of the ice sheet — some 80 metres above the lake surface, will be resumed in November, he says. But before attempting the final entry into the lake, Russia will submit a finalized environmental evaluation to the 46 members of the Antarctic Treaty at their April 2009 meeting in Baltimore, Maryland. The evaluation contains responses to concerns raised by scientists who are fearful that the drilling will contaminate the uniquely unspoiled environment.

Stopping the drill 30 metres or so above the lake surface, as SCAR recommended more than ten years ago, is not seen as an option: the Vostok project is central to the whole Russian Antarctic programme, and is a matter of national importance similar to the race to the Moon in the 1960s, says Lukin. “We will definitely drill into the lake in 2010, with Russian-developed drilling technology,” he says. “But most importantly, we'll do so in full compliance with all the rules of national and international law.”

The legitimacy of the drilling is undisputed, but concerns remain about possible biological and chemical contamination of the lake. “The Russians have met their obligations under the Antarctic Treaty,” says Chuck Kennicutt, the US delegate to, and a vice-president of, SCAR. “Ideally, they would first test the drilling technology at a less sensitive location. But there is no way of preventing them from going ahead.”

Lake Vostok lies 1,200 kilometres inland, beneath one of Russia's Antarctic stations, in one of the coldest parts of the continent. It is the largest and deepest of the 150 or so subglacial freshwater lakes that have been discovered by radar imagery beneath the Antarctic ice sheet. Similar in size to Lake Ontario, it contains more than 5,000 cubic kilometres of up to 1-million-year-old water. This water is super-saturated with oxygen and is liquid below its normal freezing point, because of the high pressure beneath the ice. Scientists believe that the sealed lake, if it is able to support microbial life, might offer a unique window into ancient DNA.

But accidental contamination could irretrievably spoil this potential ecosystem. Some contamination of the upper water layer is unavoidable when the lake is entered, says Sergey Bulat, a molecular biologist at the Petersburg Nuclear Physics Institute, where Vostok ice cores are being analysed, and where water probes will first arrive. “I don't believe the upper layer, which is basically glacier water, contains any life anyway,” he says.

To attempt contamination-free sampling of the middle and bottom layers of the lake, Russian scientists plan to release a small robotic vehicle through the transportation module in the drilling device. The Russian Academy of Sciences is expected to approve funding of around US$5 million for the 'hydrobot' programme.

Speculation about life in the virtually unexplored lake caught the attention of scientists and the public early on. But the discovery in the past few years of numerous other lakes beneath the Antarctic ice sheet, and of streams of subglacial water flowing rapidly between reservoirs, has deprived Lake Vostok of its unique status. Several proposals for drilling into moving water beneath the west Antarctic ice sheet are currently under review in the United States, for example.

“I'm not as stressed any more about Lake Vostok,” says geologist Robin Bell, of Columbia University's Lamont-Doherty Earth Observatory in Palisades, New York. “It's still special, but it is reassuring to know that there are other subglacial environments we can preserve by not probing them at all.”