Field camp at Lake Ellsworth.
Is there life in Lake Ellsworth?
13 January 2012
From November 2012, Martin Siegert from the University of Edinburgh, and Chris Hill and David Pearce from the British Antarctic Survey, will be part of one of the most ambitious Antarctic projects ever undertaken, drilling through the ice to sample the lake. Richard Hollingham met them in Cambridge to find out how they're going to do it.
Richard: I'm at the test site for the project and it looks like a series of giant yellow paddling pools with the largest garden hoses you have ever seen, connected to a series of shipping containers. Martin, just set the scene for us: where and what is Lake Ellsworth?
Martin: Lake Ellsworth is at the bottom of the West Antarctic Ice Sheet under about 3km of ice. The lake is roughly 10km long, 2 or 3km wide, and the water depth is about 150m - so it's like a rather large Scottish loch under the ice.
Richard: Why is it water?
Martin: Very simple: it's just background levels of geothermal heat that you get everywhere on the planet and that's sufficient to melt the ice - we know of about 400 subglacial lakes in various parts of Antarctica.
Richard: What do you want to find out at Lake Ellsworth?
Martin:Two main things really: is there life in subglacial lakes and what does the sediment record tell us about ice history in Antarctica? We want to understand what life exists in these places, whether it's thriving or on the edge of extinction. And the sediments on the lake floor may give us very important information about past climate change and ice-sheet change in Antarctica.
Hot-water drilling in the Antarctic.
Our plan is to access and sample the lake water without disturbing the lake unduly. To do that is rather difficult because we have to get all the way through that 3km of ice in a very clean way, and get those samples back to the surface where they can be analysed in laboratories.
Richard: Is that because there might be life there - you don't want to contaminate it?
Martin: Absolutely right. We don't want to disturb this very likely pristine environment, and we're likely to be encountering very low concentrations of the microbes and chemicals that we want to measure. If we don't keep the experiment really clean all we will measure are the things we take down with us.
David: The lake might not have been touched for 500,000 to a million years depending on the rate of accretion of ice on top of it. Subglacial lakes are the one place in the cryosphere where we really don't know what's happening; they are very likely to contain life but we just don't know what it might be.
Richard: And Chris, you're actually using hot water to drill?
Chris: That's right. Traditional drilling techniques would take a long time; hot-water drilling is the cleanest, quickest and most efficient way of accessing the lake. All the water in Antarctica is solid so we need to melt a large amount of snow, and that's what these pools are for - we need some 90,000 litres of water to start the drilling process; once we're drilling there's no problem as we'll generate lots of melted snow which we can recirculate.
We filter the water first, then heat it to approximately 97°C and run it through a bank of high-pressure pumps to get some 200,000lb per square inch. Then we can basically push the water through a 3.4km hose with a jet nozzle on the end, which melts through the ice incredibly fast.
Richard: Once you've got your hole, what do you do then?
Martin: We send down a probe which has sample chambers and measuring devices, that will be lowered down the water column taking measurements. As it does so it will scrape the sediments on the floor of the lake and take samples as it comes up. Then we'll take a 3m-long core of the sediments, pack it up and transport it back to the laboratories. We'll have high-definition cameras on the probe and the corer, so we will be seeing it in real time at the surface.
Richard: What sort of life are you expecting to find? You're not talking giant octopuses or anything like that?
The hot water drill will be used to make a 3km borehole through the ice and in to Lake Ellsworth.
David: Almost certainly not, no. It's likely to be micro life. The key organisms from our perspective are going to be bacteria because they're small enough, they proliferate enough and they're diverse enough to cope with these types of stresses and environments. We might see organisms that have adapted to survive in new ways, and we might see remnants of populations that have gone extinct elsewhere on the globe. But it's very unlikely we will see completely new things we haven't seen before.
Richard: It sounds almost like a space mission ...
Martin: There are some analogies with space science. It is a remote experiment and this type of work has never been done, so we're having to develop a lot of technology and solve a lot of problems that we hadn't imagined when we first started.
David: One of the primary requirements we know for life anywhere is liquid water, and for that reason there's been a lot of interest generated in places like Jupiter's ice-covered moon, Europa - because we know there's likely to be liquid water underneath and the conditions that are found there are likely to be conducive to life. To test that hypothesis will require more or less the experiment that we're going to do in Antarctica.
Professor Martin Siegert is principal investigator for the Subglacial Lake Ellsworth project.
E-mail: email@example.com www.ellsworth.org.uk
This Q&A is adapted from the Planet Earth Podcast 24 July 2011.
The full podcast and transcript are on Planet Earth Online:
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