Science

Monster Machines: This Drill Will Expose An Antarctic Lake Buried For 500,000 Years

Lake Ellsworth lies buried under 3.4km of Antarctic ice, cut off from the rest of the world since before the dawn of man. Who know what sort of exotic life has evolved in the frigid darkness over those hundreds of thousands of years? A British exploration team aims to find out. And this drill will get them there.

Lake Ellsworth is 11km long, 1.6km wide and 150m deep. It’s one of 387 such sub-glacial lakes already discovered in Antarctica and is thought to be completely pristine, having been isolated under the ice sheet for as long as 500,000 years. The microbial life that a team from the British Antarctic Survey hope to find may have taken a radically divergent evolutionary approach to their extreme environment. So, in order to protect the lake’s environment while exploring it, the team is utilising a specialised water drill — the largest of its kind — to bore through the ice without contaminating it with modern bacteria.

“The Drill nozzle assembly is a metre long and weighs 200kg. It consists of a single forward facing jet and a lower annulus in the body of the nozzle assembly, which produces a horizontal curtain of water,” Andy Webb, a BAS Mechanical Engineer who helped design and build the assembly told Gizmodo. “The Nozzle is connected to a 3.4km single-length 1.25-inch (31.75mm) hose, which is stored on a containerised hydraulically powered reeler. Water is fed to this at high pressure (2000psi) and high temperature (90C). The water is heated in a 1.5MW oil fired containerised boiler. The water that feeds this is stored in three 30,000-litre storage tanks before it is passed through a four-stage filter system and then UV stage making the drilling water exceptionally pure and clean.”

In addition, all of the drilling equipment and probes have been sterilised with extreme prejudice as well. They go through a four-stage cleaning process that involves being scrubbed with detergent, washed in biocide, bathed in ethanol and then blasted with hydrogen peroxide vapour. “Making equipment that is going to be robust enough to work in the environment at -20C is certainly a challenge. Many of the components that you need to create a system aren’t designed for such low temperatures,” Andy Tait, an engineer on the project, told the BBC. “Many of the companies that provide equipment won’t provide guarantees. Cold testing is of great issue in order that we have the confidence that this equipment, having been transported half way round the world, will work the first time that we use it.”

The team will arrive at Ellsworth this November during Antarctica’s short-lived summer, hopefully reaching the lake with three days of the start of drilling and returning samples by mid-December. Once they break through to Ellsworth’s geothermicaly heated waters, they’ll have just 24 hours to send probes down before the 36cm-wide bore hole refreezes closed. A single probe is made up of two pressure cases packed with instruments, power and communications systems. It will collect water samples at set depths.

A separate probe will be sent down to collect sediment samples. “We’ll get a pretty good understanding straight away whether there’s life in the lake.” Martin Siegert, the principal investigator on the project, said.

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Image: BAS

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