It is cold down in Antarctica. And to drill into the ice one needs lot of heat. In December 2012 a team of British scientists, engineers and support staff, led by Professor Martin Siegert of the University of Bristol, planned to drill through 3km of solid ice into subglacial Lake Ellsworth in Antarctica. Their mission is to search for life forms in the water and clues to past climate in the lake-bed sediments. The Bristol-led team attempting to drill 3.5 km beneath the ice of Antarctica in a search for undiscovered life have aborted their mission. Work had to be abandoned on December 15, when the field team encountered a serious problem with the main boiler that is used to generate the hot water required for drilling down to the lake. But after spare parts were flown in before Christmas, drilling seemed to be proceeding well. However the team found they were unable to properly form the water-filled cavity that needed to be created 300 meters beneath the ice. The cavity was to link the main borehole with a secondary borehole used to recirculate drilling water back to the surface.
Lake Ellsworth is a subglacial lake located in West Antarctica under approximately 3.4 km (2.1 mi) of ice. It is approximately 10 km long and is estimated to be 150 m (490 ft) in depth.
Lake Ellsworth was discovered in 1996 by British scientist Professor Martin Siegert; it is one of 387 known subglacial Antarctic lakes and it is a target site for exploration due to the speculation that new forms of microbial life could have evolved in the unique habitats of Antarctica’s sub-glacial lakes after half a million years of isolation. Life in subglacial lakes must adapt to total darkness, low nutrient levels, high water pressure and isolation from the atmosphere. Subglacial lakes thus represent unique biological habitats. The lake remains liquid deep below the Antarctic surface because the pressure exerted by thousands of meters of ice drives down the freezing point of water.
Professor Siefert said: “We have taken the decision to cease our efforts to directly measure and sample subglacial Lake Ellsworth. Although circumstances have not worked out as we would have wished, I am confident that through the huge efforts of the field team, and our colleagues in the UK, we have done as much as we possibly could have done, and I sincerely thank them all.”
“Sixteen years ago, we hypothesized that deep-water subglacial lakes are viable habitats for life, and contain important records of ice and climate history. For now, these hypotheses remain untested. Once back in the UK I will gather our consortium to seek ways in which our research efforts may continue. I remain confident that we will unlock the secrets of Lake Ellsworth in coming seasons.”
The first borehole was drilled to a depth of 300m and then left at that depth for 12 hours to create the initial cavity. The second, main borehole (located two meters away from the first) was then drilled to 300m depth and should have immediately connected with this cavity.
This main borehole would then continue through the cavity and down to the lake while the first borehole would be used to circulate water back to the surface using a submersible pump. In this way there would be an intermediate hole to relive sudden pressure and to limit contamination with surface waters.
For reasons that are yet to be determined the team could not establish a link between the two boreholes at 300m depth, despite trying for more than 20 hours.
Bowing to the problems of no connection, and running low on fuel, the drilling attempt was stopped.
Professor Siegert said: “This is of course, hugely frustrating for us, but we have learned a lot this year. By the end the equipment was working well, and much of it has now been fully field tested. A full report on the field season will be compiled when the engineers and program manager return to UK.”
For further information see Drilling.
Article by Andy Soos, appearing courtesy Environmental News Network