Geoscientist Martin Siegert says that drilling through 3 kilometres of ice to reveal the secrets of an entombed lake was never going to be easy
Why do you want to drill through 3 kilometres of ice to tap Lake Ellsworth, which has been undisturbed for half a million years?
We are trying to test two hypotheses: that life exists in ancient deepwater subglacial lakes, and that sediments on these lake floors contain important climate records, potentially revealing the history of the West Antarctic ice sheet.
Why did you have to stop the pioneering hot-water drilling on Christmas Day?
Our procedure was to drill down 300 metres with a short hose, and pause it there to create a cavity of water, which would then be pumped to the ice surface and used to supply water to the main hose, 3400 metres in length. Once the cavity was established, the main hose was drilled to 300 metres and should have connected to the cavity. This is necessary as the pump in the short hose could then be used to regulate the pressure in the main borehole - vital prior to lake entry. The problem was that the main hose did not connect to the cavity. Our attempts to do this reduced our fuel supply to the point where we could no longer reach the lake even if we did connect to the cavity.
How did it feel to make that decision, after many years of preparation?
It was a really sad moment, but the information we had was easy enough to interpret and the call to stop was unavoidable. The annoying thing is that despite our difficulties, we were very close to being successful. If we had linked the cavity, the drill to 3000 metres was not a technical challenge.
What happens next?
We are determined to learn from our experience, and to put the lessons learned to good use in a revised plan. Realistically, this is likely to take three to five years, as equipment needs to come back to the UK, be serviced and modified, and then installed back in Antarctica. We really do wish to see it through to completion. Science is often characterised by setbacks. Our challenge is to deal with these professionally and to make sure that when we try again we are successful.
What positives do you take home with you?
We've learned a great deal. No one has drilled this far before using the technique. We have trialled the whole system in Antarctica and it works well. Our field site and its logistics are well suited to the experiment. Our probe deployment system was field-trialled. Our sterility protocols work well. In fact, bar the issue with the cavity, the actual running of the experiment worked very well. We have much to be positive about, although of course we are hugely disappointed that we didn't do what we wished to this time.
Might your efforts inform plans to check the frozen oceans of icy moons in the solar system for signs of life?
Our need for cleanliness is certainly similar to that used in space science, and the experiment itself is comparable; using a remote device to measure and sample an extreme environment. I think there is a lot that future space missions might learn from our work, which is one of the reasons for us to be so open about things, both good and bad!
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