After 20 million years below the Antarctic ice, Lake Vostok will finally reveal its secrets
At the bottom of the Earth, two miles below Antarctica’s ice sheet, scientists have broken a 20-million-year silence. A Russian team has drilled 3,770 metres (2.3 miles) through the polar ice to a vast freshwater lake, called Lake Vostok. It has lain undisturbed for four times as long as human beings have been separate from apes.
It has taken the team 22 years to drill through, and the day after they achieved their goal they had to leave, before the brief Antarctic summer came to an end and the air became too cold for aeroplanes to fly. So it will not be until December that any frozen samples can be retrieved, and not until the end of next year that liquid water from the vast lake, as large as Lake Ontario, will be examined.
As well as the physical peril for the researchers, there is the risk of contaminating this most untouched of wildernesses – so the team are going to extraordinary lengths to avoid bringing the germs and chemicals of the outside world into Vostok’s black depths.
When they do bring samples to the surface, what do they hope to find? Dr Lewis Dartnell, an astrobiologist at University College London, says that for the study of life, both on Earth and elsewhere in the universe, it could be a breakthrough. “It’s a pristine environment,” he says. “It’s like discovering a lost world – we have no idea what’s in there, after 20 million years sealed off from the rest of the biosphere. Even if it’s only microbial life we find, it’s a completely new habitat.”
Its self-contained nature will also help us. Fully understanding the carbon and nitrogen cycles, and the behaviour of other nutrients and elements, should give a clue to how they work on Earth as a whole. Yet it is as a mirror of other worlds that Vostok is most exciting. There are a few places on Earth – the Atacama Desert in Chile, or the McMurdo Dry Valleys in Antarctica – that are analogues of Mars: cold, dry and harsh. Lake Vostok and the other sub-surface lakes of Antarctica are analogues for Europa, Jupiter’s ice-moon, which is considered the most likely place in the solar system for life to be found.
“The Europan ocean is also miles deep below solid ice and doesn’t have any sunlight,” says Dr Dartnell. “So life in Lake Vostok would be in a very similar environment. You don’t get to rely on plants, or the oxygen or food they produce.” Instead, life would be geothermal, relying on the heat of the planet, or chemo-autotrophic, relying on energy from inorganic ions.
This world will be one of utter dark, incredible cold, and crushing pressure: more than two and a half tons per square inch. But, weirdly, it’s not impossible that there will be complex life down there. “The pressure isn’t a problem, because you find animal life at very high pressures at the bottom of the ocean,” says Dr Dartnell. Crabs and fish live in the Challenger Deep, seven miles below the surface of the Pacific, at pressures of well over 10 tons per square inch. Similarly, the cold isn’t a problem: there are insect-like creatures called ice crawlers that live on frozen mountaintops at -20C (-4F), with natural antifreeze in their bodies.
What may limit the size and complexity of the life that exists in Vostok’s pressure-freezer is the amount of energy and oxygen. “There probably isn’t enough energy in the system for animal life,” says Dr Dartnell. “And Vostok is almost certainly anoxic – there’s no oxygen dissolved there. Until a year or so ago, there was not a single example of an animal that could spend its life cycle without oxygen.”
The discovery of an anaerobic animal, in the sediment at the bottom of the Mediterranean last year, overturned a lot of what was thought to be known about animal life, but the odds against it happening again are high. But as Dr Dartnell says, whatever we find, “it’s going to be special stuff, unique stuff, lifeforms we’ve never enountered before”. And it will shed new light on distant worlds.