Tuesday, February 7, 2012

Race Against Time for Raiders of the Lost Lake by Quirin Schiermeier

Arguably the most exciting — and certainly the most controversial — scientific endeavor in Antarctica's history is close to a breakthrough.

A Russian drilling team is just metres away from reaching the water surface of Lake Vostok, the largest and deepest of the freshwater lakes hidden beneath Antarctica's massive ice sheet.

The ambitious project, launched more than 20 years ago, has been repeatedly delayed by technical glitches and funding problems (see Nature 464, 472–473; 2010). But Russian researchers, who on 2 January resumed drilling at a depth of 3,650 metres, believe that just 20–40 metres or so of accretion ice — frozen lake water — now separate them from the lake's liquid surface. "We can make it this time," Valery Lukin, director of the Russian Antarctic programme, told Nature

 But time is short. Although the drill can advance by about 3 metres each day, the team must call a halt by 6 February, when the last aircraft of the summer research season is due to leave the Vostok research station, about 1,300 kilometres from the South Pole (see 'Drill for victory'). If they haven't reached the lake by then, they will have to wait until December to continue, Lukin says.

The chance of sampling one of the last uncharted environments on Earth has excited researchers ever since the lake's existence was first mooted in the 1970s. Many are thrilled by the possibility of discovering evidence of unique life forms in the lake, which is thought to have formed as much as 35 million years ago. But others worry that the drilling effort could contaminate an untouched environment. The lake may hold traces of ancient microorganisms that could reveal how life on Earth has adapted to extreme conditions.

At the Vostok station, tension is rising with every passing day. The team hopes that a sensor attached to the drill head will signal contact with liquid water in the next few weeks. At that point, the drill will be stopped and extracted from the bore hole, thereby lowering the pressure beneath it and drawing water into the hole. This should prevent any of the silicone drilling lubricant from entering the lake, explains Lukin. The rising water will rapidly freeze in the borehole, where drillers can extract it without penetrating the pristine lake. "If everything goes according to plan, we will re-core the hole in December and retrieve the frozen sample without polluting the lake water," he says

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