Hard work to uncover secrets

Lake Vostok is one of the most exciting places for scientists in the world today

This huge body of water has been cut off from the rest of the world for as many as 14 million years, though experts can’t put an exact figure on it. And the lake’s hidden under nearly four kilometres of ice, so it’s not easy to access.

Now, Russian scientists are working hard to uncover the secrets of Lake Vostok. They want to find out what might have been able to survive inside this extreme and sunless environment.

They believe that conditions in the lake are similar to those on Jupiter’s moon, Europa - where it’s thought that an ocean is concealed under an icy crust.

Finding out more about the lake may enable scientists to understand more about Europa.

In order to do that, they need to analyse the lake’s water.

A Russian team penetrated the lake in spring 2012, after decades of drilling through the ice.

Biologist Dr Sergei Bulat, who runs the cryo-astrobiology group at the Kurchatov Nuclear Physics Institute in St Petersburg, is at the forefront of efforts to find out what’s inside the lake.

He’s currently testing samples of frozen water retrieved by the Russian drillers.

Life, but not as we know it

Dr Bulat’s task is to find out whether the lake contains any forms of life, known or unknown – and this means microbes rather than large organisms.

I caught up with him at the Laboratory for Glaciology and Environmental Geophysics in Grenoble.

French and Russian scientists have been working together on Antarctic research since 1980.

The laboratory in Grenoble, like only a few in the world, has facilities that are ideal for working with ice.

“After last spring, after March 2013, we continue to carry out molecular DNA studies of on the water from Lake Vostok that was frozen in the borehole, by constructing numerous DNA libraries,” says Dr Bulat. DNA libraries, or gene banks, are collections of fragments of DNA which allow scientists to identify which species bacteria may belong to.

In this case, Dr Bulat needs to build DNA libraries in order to try to determine what’s inside Lake Vostok. The key problem is that all the samples taken from the lake so far are contaminated with drilling fluid. Even a tiny amount of contamination means that it is extremely difficult for scientists to understand whether the water sustains life, and if so, what kind.

Dr Bulat has been working with two different groups of samples. The first group of samples was collected in February 2012, when the Russian team first penetrated the lake. This is what Dr Bulat calls the ‘drill bit water,’ because it touched the end of the drill that was used to penetrate the lake.

Unfortunately this water was heavily contaminated with drilling fluid – the kerosene used to keep the borehole from closing up.

The second group of samples of frozen water was collected in spring 2013, when lake water rose up the borehole and froze. But it turned out that this water was also contaminated with drilling fluid.

“The main problem still is that we work with ‘dirty’ water,” says Dr Bulat. “When the [lake] water touched the drill, the drill-bit water - when I melted it, this frozen water, the sample was half and half water to kerosene. This means it was contaminated. It was frozen along with the kerosene.”

“And the new water [from 2013], it’s much cleaner, the borehole water. Much cleaner. But still it has - not plenty, but certainly it contains - drilling fluid. It smells a lot of kerosene and even contains some micro-droplets of kerosene. So it’s again mixed, not 50-50 but maybe 1000 to 1 or 10,000 to 1, but still, contaminated. That is why the problem is that we are always working on water from the lake that is not [perfectly] clean,” he says.

Photo: The Vostok station in 1990 (Russian Antarctic Expedition)

Building a library

Dr Bulat and his colleagues have built what they call a ‘contaminant library,’ or a gene database containing different kinds of contaminants.

By November this year it contained 255 species, or phylotypes, of bacteria, and the library is still growing.

The scientists can then use this library of data to compare Lake Vostok’s bacteria with other bacteria – in order to find out whether the lake water contains known contaminants.

As Dr Bulat says, the library is not full, because it would be impossible to classify all the contaminants in the world - but it will help to rule certain things out. “Our task now is to analyse these new DNA clones, to sequence them, and then to compare [them] with this contaminant library,” he explains.

“If the bacteria fits some stuff here, this new bacteria should be considered as contamination. But still the library is not full, because of course, we could not establish a full library which would include all contamination.

“Some could escape and the problem with new stuff is - how do we define contamination? Not all contaminants are present in our library, but still – 255 are.”

Frozen

Dr Bulat has already produced some results.

Earlier this year, he said that the first samples of frozen water from Vostok, obtained in 2012, contained a bacterium with no matches in any international databases. He said this bacterium was unidentified and unclassified.

But he was challenged by others in the scientific community, who said the bacterium was unlikely to be unknown or unique, and that scientists will not know more until they can test clean samples of lake water, uncontaminated by drilling fluid.

Dr Bulat has also been testing the second lot of samples collected in 2013. He has not yet found any unclassified bacteria in the samples, but he says he has identified a bacterium in them which is distantly related to those that live in water. This may be an indication of what lives inside the lake.

Dr Bulat thinks it is likely that the lake contains unknown bacteria. Because the lake was cut off for so long, there has been significant evolutionary pressure on it.

Feel the force

Evolutionary pressure is the force with which evolution enables new species to develop.

“We consider that the lake conditions are so extreme that the lake was covered - let’s say for 14 million years – the evolution pressure should be very hard, and the species should be considered completely new. I mean far from known earthly stuff,” says Dr Bulat.

He must test the lake samples at the laboratory in Grenoble because of its first-class facilities. It has a number of cold rooms of varying temperatures in which scientists can work on ice cores - large cylinders of ice removed by the drill - cutting off pieces of ice with electric saws, decontaminating it, and analysing its properties. The laboratory also has clean rooms where scientists can melt the ice and extract DNA without contaminating the samples.

For now, there are no such facilities in Russia – they are extremely costly to construct - though Dr Bulat says his institute plans to build similar facilities next year.

Don’t give up

There is no doubting the excitement within the scientific community about what might be discovered in Lake Vostok.

Vostok is the biggest of several hundred lakes buried under Antarctica, covering 15 square kilometres and with depths of 1,200 metres.

The British have been working to penetrate another sub-glacial lake, Lake Ellsworth in West Antarctica, using a hot water drill.

It’s also located deep under the ice, at a depth of over three kilometres, though it is much smaller than Vostok - it’s about 150 metres deep and covers about 29 square kilometres.

Drilling was called off in 2012 due to technical problems.

British scientists are working on ways to pierce the ice using hot-water drilling, which is seen as the only method that will avoid contamination of the lake, but it is technically challenging. It may be several years before work can be restarted.

Meanwhile, the United States penetrated Lake Whillans in early 2013. This lake is not as deeply buried as the other two, however – it’s located just 800 metres under the surface of the ice.

Summer nights

The Russian team is now in full swing at their research station, which is named Vostok, just like the lake.

A group of scientists and drillers arrived in early December and have just two months to carry out a long list of jobs before they must return to their home city of St Petersburg.

After that, the Antarctic summer ends – and the weather becomes so severe that it’s impossible to fly a plane out of the base.

It is unclear yet whether the Russian team will penetrate Lake Vostok again during this season, and bring new samples of lake water to Dr Bulat.

But Vostok isn’t only important to biologists.

Glaciologists have vital work to do here, looking at the ice below the surface of East Antarctica.

The Russians have been extracting ice cores at the Vostok station - long cylinders of ice - since the 1960s. Much of what is known about the last 400,000 years on earth comes from the study of these pieces of ice.

The glaciologists slice off small samples of the ice core and test them, extricating valuable information about the climate of the past. They also check the amount of snowfall around the base, analyse samples of snow, measure its temperature, and carry out many other essential tasks.

Photo: The polyarniki, or polar men, who work at Vostok displaying ice cores they have drilled from below the surface of Antarctica (Russian Antarctic Expedition)