Icy waters of Lake Ellsworth
Dr Henry Lamb holding a section of core from Lake Suigetsu, Japan.
14 December 2012
As a British team of scientists and engineers realise a 16 year ambition to drill down through over 3 km of Antarctic ice into an ancient buried lake this week, a small team of scientists at Aberystwyth University will be keeping a very close eye on proceedings.
Dr Henry Lamb from the Institute of Geography and Earth Sciences at Aberystwyth is an expert in analysing sections of mud taken from the floors of lakes around the world.
Detailed analysis of the mud using an x-ray scanner, a technique developed by Dr Lamb at Aberystwyth University, has enabled scientists to build a record of environmental change that extends back over thousands of years.
Dr Lamb was a leading member of an international team that recently analysed sediment cores from Lake Suigestu in Japan.
The work, which was published in Science, the journal of the American Association for the Advancement of Science (AAAS), in mid-October of this year, led to extending the accuracy of radiocarbon dating from 12,000 years or so to nearly 54,000 years.
Now Dr Lamb is hoping that the team drilling into Lake Ellsworth, which lies 3km below the ice in Antarctica, will successfully remove a section of mud from the lake’s floor.
“It will be fascinating to see what we get from the Ellsworth sediment core,” said Dr Lamb. “Aberystwyth’s X-ray fluorescence core scanner will show its geochemical composition in great detail. By matching the sediments to what we know of the rocks beneath the ice sheet, we should be able to gain some insight into the history of ice formation and movement in this part of Antarctica.”
If all goes well, the work of analysing the section of mud is expected to start in Aberystwyth in early in 2013.
The drilling of Lake Ellsworth
Using a high-pressure hot-water drill specially designed for the mission the 12-man team have started to bore a hole through solid ice into Lake Ellsworth on the West Antarctic Ice Sheet. The drilling started on Wednesday 12 December 2012.
It will be a race against time to keep the access borehole open long enough to lower and raise two state-of-the-art instruments that will collect water samples from the lake surface to the lake bed, and a core of mud from the lake floor.
The team can only keep the borehole open for 24 hours before it refreezes to an unusable size, ultimately sealing the lake off again.
Precision engineering and technology are at the heart of this scientific experiment. The hot-water drill, designed by British Antarctic Survey (BAS) engineers will take around five days of continuous drilling through the ice to reach the lake.
A titanium probe, designed by a team at the National Oceanography Centre (NOC) will collect water samples and data. A sediment corer developed by BAS with Austrian partners will capture lake-bed mud samples.
The science team thinks that unique forms of microbial life could have evolved in Lake Ellsworth’s extremely cold, pitch black and pristine environment and these may have been isolated for up to a million years.
If so the lake will provide clues about the potential origin of and constraints for life on Earth, and shape scientific thinking about the evolution of life on other planets. If no life is found this would be an equally valuable result that indicates the limits of life on Earth.
Sediment samples (mud) from the lake are expected to yield important insight in to the ancient history of the West Antarctic Ice Sheet and reveal vital secrets about the Earth’s past climate. This will have implications also for our understanding of future sea level rise.
It has taken the ‘Deep Field Team’ four weeks to set up living and working facilities at the camp; to prepare and test the drill rig; and ensure final sterility measures are in place before drilling commences.
The drilling mission is made up of four-stages:
1. Pump a high pressure jet of hot water slowly into the ice to create a borehole that is around 40cm wide
2. Create a chamber in the ice (the size of a caravan) 300 metres below the surface, fill with hot water, place a water pump inside to balance the pressure and prevent lake water rushing back up the borehole when the lake is penetrated. This should take around two days of constant drilling
3. Continue to drill the borehole for approximately three days more, going deep through the ice and into the lake
4. Lower and raise the instruments to retrieve water and sediments samples for analysis in UK laboratories – the team has just 24 hours to complete this stage before the hole re-freezes to an unusable size
To protect Lake Ellsworth’s pristine environment and to ensure that uncontaminated samples are brought back to the UK for analysis, space-industry-standard clean technology has been used to sterilise every piece of equipment.
This included a four-stage chemical wash followed by full exposure to hydrogen peroxide vapour (HPV) during the final assembly process. All equipment was transported from the UK in sterile packaging and will be treated with HPV again on site.
The water used for drilling undergoes a four-stage filtration process, down to 0.1 microns, before being passed under UV light and heated to 90 degrees C.
Lake Ellsworth Principal Investigator Martin Siegert from the University of Bristol said, “This British mission is part of an international effort to discover and explore sub glacial lake environments. We are about to explore the unknown and I am very excited that our mission will advance our scientific understanding of Antarctica’s hidden world. Right now we are working round the clock in a cold, demanding and extreme location – it’s testing our own personal endurance, but it is entirely worth it.”
Lake Ellsworth Programme Manager and Expedition Leader Chris Hill from British Antarctic Survey said,
“A major milestone last year was getting the bulk of the equipment and supplies to the site - the logistical effort alone to get 100 tonnes of equipment to Lake Ellsworth has been phenomenal. Now everything we’ve planned and prepared for is about to happen and it’s tremendously exciting – if not a little nerve-racking!”
Lead Hot-Water Drilling Engineer Andy Tait from British Antarctic Survey said,
“This is a huge, but delicate operation. Although hot-water drilling technology has been used extensively by scientists in the past, this is the first time we’ve ever attempted to go through 3km of solid ice - this will be the deepest borehole ever made this way. We’ve fired up the boilers to heat the water to 90°C. The water pressure coming out of the hose will be around 2,000 PSI – 15 to 20 times more powerful than the kind you wash your car with. It is the most effective way to obtain rapid, clean access to Lake Ellsworth.”
The Lake Ellsworth Consortium is funded by the Natural Environment Research Council. It features two of NERC’s Centres of Excellence – British Antarctic Survey and the National Oceanography Centre – and nine UK universities.