In 1996 I was fortunate to be involved in the discovery of Antarctic subglacial lakes as deep isolated water bodies beneath vast ice sheets. I and several others hypothesised that these lakes were viable habitats for life, and that they contained unique and important records of ice sheet and climate change. Now, 16 years on, we stand at the threshold of testing these hypotheses, as we head off to explore subglacial Lake Ellsworth in West Antarctica.
Our aim is to send equipment into the lake to obtain samples of lake water and lake floor sediment, bring them back to the ice surface, and transport them to UK laboratories where they can be examined. The challenge we face is significant. The lake lies beneath approximately 3000 m of ice. We must first drill a hole from the surface sufficiently large that our instruments can be deployed. As the lake is pristine, we must do this in a way that does not contaminate or disturb it. Our instruments, which must be as clean as it is possible to be, need to work under immense pressure, and capture and preserve samples that will undergo significant pressure and temperature changes upon retrieval. When we are finished, our footprint must be minimal.
Meeting the challenges
To get to this threshold has itself been a significant achievement. The first meeting of the team configured to plan the project was in 2003. Since then we have undertaken two seasons of geophysical surveys, from which our knowledge of the size and shape of Lake Ellsworth, and its glaciological setting within West Antarctica, have been established. Logistical arrangements for the transport of around 100 tons of equipment to the middle of the ice sheet have been designed. A drill, which uses high pressured hot water, capable of melting a clean 36 cm wide hole to the base of the 3000 m thick ice sheet has been designed, built, tested and taken to Antarctica. We have designed, built and tested a probe capable of sampling and measuring the lake water, and a sediment corer to extract material from the lake bed.
Our drill melts glacier ice, which is then passed through a fine filter to remove particles and microbes and a bank of powerful UV radiators to kill any remaining bacteria. The water is heated to 90 degrees, pressured to 2000 psi, pumped into a continuous 3.4 km hose to a nozzle at the end, which disperses the water in a manner that shapes a perfectly circular hole.
The challenge of developing the probe has been considerable. It comprises over 3000 individual components, each of which have undergone strenuous cleansing, involving scrubbing in detergent, washing in biocide, bathing in ethanol and, finally, subjecting to hydrogen peroxide vapour. It is made largely from high grade titanium. It is around 5 m in length, and 20 cm wide. It has HD cameras looking upwards and downwards, and is fully controllable from the ice surface. We will, therefore, see the moment in which the probe enters the lake, and will view for the first time the underside of the West Antarctic ice sheet and the lake floor. Through testing, we are confident the probe will have a high probability of success. Just to make doubly sure, we are taking two identical probes.
Our sediment corer has also been fully tested. It uses a percussion technique to hammer into the sediment allowing even hard material to be covered. Once stuck in the sediment, a huge surface winch will pull the corer out and up through the drill hole back to the surface.
Leaving nothing behind
Once we have recovered the equipment we will allow the drill hole to freeze, leaving no trace of our entry and exploration, other than the samples we have taken.
To get to this stage has required huge efforts from many of our expert engineers and scientists from several UK Natural Environment Research Council institutions and UK universities. The probe has been built by staff at the National Oceanography Centre in Southampton; the drill and corer by the British Antarctic Survey in Cambridge, from where the project is also managed. I have been overwhelmed by the efforts of staff in these centres, and I offer my sincere gratitude to them.
We first thought about exploring subglacial lakes 16 years ago and now we are finally on the cusp of launching our plans and turning dreams of this exploration into a reality. While the journey getting to this point has been hard we realise we are still only at the beginning. I hope that you will follow our progress from here, as we head to Antarctica in the coming months, and undertake one of the most challenging and important
polar scientific exploration missions ever conducted. If we are successful, the samples will come back to the UK for full scientific examination. We are excited at what lies ahead yet fully aware of the challenge it presents.
Please follow our progress on this website, on Twitter and Facebook
And, finally, wish us good luck!