BOX 1.2

An Eight-Year Plan for the Exploration of Subglacial Lake Ellsworth

The comprehensive geophysical survey of Lake Ellsworth is planned to occur in two seasons during IPY 2007-2009 and will include RES, seismic surveying, and a variety of surface measurements. Discussion of the feasibility of a U.K.-led subglacial lake exploration program began at the British Antarctic Survey in April 2004. Currently, a consortium of more than 30 scientists from seven countries and 14 institutions is planning to access Lake Ellsworth using hot-water drilling. The project will involve a geophysical survey; instrument development; hot-water drilling and fieldwork; biological and geochemical analysis of water samples; and sedimentological analysis of lake floor deposits.

Phase 1—Geophysical Exploration (3 years): The size and shape of Lake Ellsworth, flow of the ice sheet over the lake, and subglacial topography surrounding the lake will be measured. Objectives include measuring water depth, sediment thickness across the lake floor, and dimensions of the lake’s drainage basin.

Phase 2—Instrument and Logistic Development (2 years): Equipment will be assembled and logistics for physical exploration will be planned. Probes will be built and tested to measure the physical and chemical properties of the lake’s water and to sample lake water and sediment. Objectives include developing a means of communication between the probe and the ice surface; building and testing a hot-water drill; and acquiring and testing a sediment corer capable of extracting a 2- to 3-m core from the floor of Lake Ellsworth to recover climate records.

Phase 3—Fieldwork (1 year): A hot-water drill will be used to bore a 30-cm-wide hole to gain access to the lake from the ice sheet surface. It is anticipated that the borehole will be held open for 24-36 hours. Just before the drill enters the lake, the water generated during drilling will be removed to ensure that the borehole water does not enter the lake. Once the lake is reached and lake water floods into the borehole, a probe capable of measuring the lake’s biology, chemistry, and physical environment will be deployed through the water column to the lake floor and subsequently retrieved. A sediment corer will be used to retrieve a 2- to 3-m sediment core.

Phase 4—Data Analysis and Interpretation (2 years): Data, sediment, and samples acquired by the probe will be analyzed to comprehend the physical and chemical structure of the lake; ascertain the form, level, and distribution of microbial life in the water column and water-sediment interface; undertake geochemical analysis; and if a sediment core is acquired, analyze sedimentary records.

SOURCE: Michael Studinger, Lamont-Doherty Earth Observatory of Columbia University.

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