Exploration of Ellsworth Subglacial Lake: a concept paper on the development, organisation and execution of an experiment to explore, measure and sample the environment of a West Antarctic subglacial lake |
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Authors: | MJ Siegert A Behar M Bentley D Blake S Bowden P Christoffersen C Cockell H Corr D C Cullen H Edwards A Ellery C Ellis-Evans G Griffiths R Hindmarsh D A Hodgson E King H Lamb L Lane K Makinson M Mowlem J Parnell D A Pearce J Priscu A Rivera M A Sephton M R Sims A M Smith M Tranter J L Wadham G Wilson J Woodward |
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Institution: | (1) School of GeoSciences, University of Edinburgh, Grant Institute, West Mains Road, Edinburgh, EH9 3JW, UK;(2) Jet Propulsion Laboratory, NASA, Pasadena, USA;(3) Department of Geography, Durham University, Durham, UK;(4) British Antarctic Survey, Cambridge, UK;(5) Department of Geology and Petroleum Geology, University of Aberdeen, Aberdeen, UK;(6) Scott Polar Research Institute, University of Cambridge, Cambridge, UK;(7) CEPSAR, Open University, Milton Keynes, UK;(8) Cranfield Biotechnology Centre, Cranfield University, Cranfield, UK;(9) Division of Chemical and Forensic Sciences, Bradford University, Bradford, UK;(10) Surrey Space Centre, University of Surrey, Guildford, UK;(11) National Oceanography Centre, Southampton, University of Southampton, Southampton,, UK;(12) Institute of Geography and Earth Sciences, University of Wales, Aberystwyth, Aberystwyth, UK;(13) Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, USA;(14) Centro de Estudios Cientificos, Valdivia, Chile;(15) Department of Earth Science and Engineering, Imperial College, London, London, UK;(16) Space Research Centre, University of Leicester, Leicester, UK;(17) Bristol Glaciology Centre, University of Bristol, Bristol, UK;(18) Department of Geology, University of Otago, Dunedin, New Zealand;(19) Division of Geography, Northumbria University, Newcastle, UK |
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Abstract: | Antarctic subglacial lakes have, over the past few years, been hypothesised to house unique forms of life and hold detailed
sedimentary records of past climate change. Testing this hypothesis requires in situ examinations. The direct measurement
of subglacial lakes has been considered ever since the largest and best-known lake, named Lake Vostok, was identified as having
a deep water-column. The Subglacial Antarctic Lake Environments (SALE) programme, set up by the Scientific Committee on Antarctic
Research (SCAR) to oversee subglacial lakes research, state that prior exploration of smaller lakes would be a “prudent way
forward”. Over 145 subglacial lakes are known to exist in Antarctica, but one lake in West Antarctica, officially named Ellsworth
Subglacial Lake (referred to hereafter as Lake Ellsworth), stands out as a candidate for early exploration. A consortium of
over 20 scientists from seven countries and 14 institutions has been assembled to plan the exploration of Lake Ellsworth.
An eight-year programme is envisaged: 3 years for a geophysical survey, 2 years for equipment development and testing, 1 year
for field planning and operation, and 2 years for sample analysis and data interpretation. The science experiment is simple
in concept but complex in execution. Lake Ellsworth will be accessed using hot water drilling. Once lake access is achieved,
a probe will be lowered down the borehole and into the lake. The probe will contain a series of instruments to measure biological,
chemical and physical characteristics of the lake water and sediments, and will utilise a tether to the ice surface through
which power, communication and data will be transmitted. The probe will pass through the water column to the lake floor. The
probe will then be pulled up and out of the lake, measuring its environment continually as this is done. Once at the ice surface,
any water samples collected will be taken from the probe for laboratory analysis (to take place over subsequent years). The
duration of the science mission, from deployment of the probe to its retrieval, is likely to take between 24 and 36 h. Measurements
to be taken by the probe will provide data about the following: depth, pressure, conductivity and temperature; pH levels;
biomolecules (using life marker chips); anions (using a chemical analyzer); visualisation of the environment (using cameras
and light sources); dissolved gases (using chromatography); and morphology of the lake floor and sediment structures (using
sonar). After the probe has been retrieved, a sediment corer may be dropped into the lake to recover material from the lake
floor. Finally, if time permits, a thermistor string may be left in the lake water to take time-dependent measurements of
the lake’s water column over subsequent years. Given that the comprehensive geophysical survey of the lake will take place
in two seasons during 2007–2009, a two-year instrument and logistic development phase from 2008 (after the lake’s bathymetry
has been assessed) makes it possible that the exploration of Lake Ellsworth could take place at the beginning of the next
decade. |
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Keywords: | Subglacial lakes Extreme environments Exploration Antarctica |
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