Nothing to see here – at least not yet. Lake Vostok, the vast body of water hidden beneath the Antarctic ice sheet, has so far shown no signs of life.
Isolated from the rest of the planet for 14 million years, Lake Vostok might be the only body of water on Earth to contain no life whatsoever. However, if life is found, it will be a big boost for researchers hoping to find microorganisms on icy moons like Europa.
A Russian team became the first to breach Lake Vostok on 5 February, after drilling down through over 3.5 kilometres of ice. To avoid contaminating the lake, their drill bit automatically withdrew as soon as it struck water. That water rose 30 to 40 metres up the borehole, forcing the drilling fluid away from the lake. The water then froze.
Sergey Bulat of the Petersburg Nuclear Physics Institute in St Petersburg, Russia, and colleagues have now analysed the water – contaminated with some drilling fluid – that froze onto the drill bit at a depth of 3714 metres. He counted cells and looked for traces of DNA.
In preliminary results, reported at last week’s 12th European Workshop on Astrobiology in Stockholm, Sweden, Bulat says there were only about 10 cells in every millilitre. There was also DNA from four species of bacteria, three of which were known to exist in the drilling fluid. The fourth was able to degrade the hydrocarbons within fluid to release energy, suggesting it had adapted to life inside the fluid. Bulat thinks none of the bacteria came from the lake.
He cautions that we cannot yet be sure that the upper layers of Lake Vostok are devoid of life, as microorganisms could be living at low densities that he could not reliably detect. “The concentrations expected for indigenous stuff are very low,” Bulat says.
It will not be possible to draw firm conclusions until the team returns to the area in December. They should be able to pull up more ice from the depths of the borehole, most of it uncontaminated by the drilling fluid.
Lake Vostok is one of many subglacial lakes in Antarctica. There are plans to drill into two others, Ellsworth and Whillans.
Ellsworth could yet become the first Antarctic lake to yield life. A British team plans to drill into it within the next few months, and will lower in a probe that will collect samples of sediment from the bottom.
That gives them an advantage over the Russian team. Lake sediments are the most promising places to find life, but the Russians do not have a firm plan to drill into them as yet.
The sediments are produced as the ice sheet grinds slowly over the underlying rocks, and will contain mineral nutrients from the rocks that could sustain microorganisms. The pitch-black water will contain little for the bugs to eat, so it’s unlikely there is much life there.
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