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The team will have just 24 hours to access the lake before the borehole refreezes. Although hot-water drilling technology has been used extensively by Antarctic scientists on previous experiments, at 3 km this will be the deepest borehole ever made this way.
The hot water drill is designed to cope with extraordinary environmental conditions. It needs to operate continuously for 3 days to create a 360 mm wide borehole through the ice into the lake. At -20°C freezing inside the borehole reduces its diameter by 0.6 cm per hour. Ice and water from the hole need to be recycled as drilling fluid to minimize the potential for contamination.
Not only must the drill penetrate 3 km of ice, it must also be free from contamination. It's a major challenge to design, source and manufacture the specialized equipment and components required for this project. And of course, all of this gear had to make the long journey from the UK to Antarctica in containers that can fit inside an aircraft.
Adavanced Insulation Manufacturing Ltd Technical Director Les Johnson designed an insulation system to protect the all-important drill head using components provided by NMC UK for the polyethylene foam insulation, and Pentair Thermal Management for the Thermal Heat Trace.
Les had this to say on his contribution to the project: "This is a fascinating project and we would be very pleased to play a small part in helping it reach its objectives.
"When the hot water drill is in use, a filtration and UV system remove any bacteria and viruses present in the melted water for drilling and a stainless steel heat exchanger, connected to the boiler heats water as it flows through. Gravity guides the hot water drill, forming a very straight hole as it moves down through the surface into the lake. A winch system controls the descent of the hose and drill into the lake pressurized to 2,000 PSI, and heated to 90°C, water melts a hole in the ice at a rate of ½-1 m per minute. The hot water drill uses a nozzle that works a bit like a jet spray used to clean your car.
"While on location at Lake Ellsworth the engineering team are constructing a continuous 3.4 km hose that is strong enough to support its own weight and that of the drill nozzle, an industrial-sized 1.5MW boiler to heat 30,000 litres of hot water (90°C) for the drill, three large surface tanks (each with a 5 metre diameter) to store water above freezing point in temperatures as low as -20°C and several large-scale generators to provide electrical power to the boiler and drill."
