US designed hot-water drill reaches subglacial lake
ISO ski kits were used to transport the drill modules across the Ross Ice Shelf by tractor (Credit: Frank Rack)
A cutting-edge hot-water drill designed by US engineers has broken through 800-metres of ice above a subglacial Antarctic lake.
Following more than a decade of planning and three and a half years of project preparation the team successfully drilled through the ice sheet above Lake Whillans, at the Southeastern edge of the continent, near the Ross Sea.
The Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) team used a powerful jet of pressurized hot water to melt a hole in the ice, reaching the lake yesterday.
Dr. Frank Rack, from the University of Nebraska, Lincoln, led the team that designed and operated the drill, the construction of which was funded by the U.S. National Science Foundation.
He said: “At the University of Nebraska-Lincoln, we are very happy to have accomplished this milestone after spending the past 20 months building the WISSARD hot water drill system and having it traverse over 600 miles to the drilling location on the Whillans Ice Stream. Everyone involved in the project has done a great job.”
They are only the second team to achieve the feat after a British Antarctic Survey mission to drill through two miles of ice to reach Antarctica’s Lake Ellsworth ended in failure last month. The first country to do so was Russia, whose scientists drilled to Lake Vostok last February.
Scientists hope data collected from the drilling will give them insights into subglacial microbial life, climate history and contemporary ice sheet dynamics.
The engineering team were given the task of designing and producing a modular system able to travel over ice and made largely from commercial off the shelf components to make replacements easier – no mean task considering the hostile environment it operates in.
Contamination of the lake’s pristine environment with microbes from above created an extra challenge, a problem countered by feeding the drilling hose through a collar of ultraviolet lamps to kill 99.9% of all microorganisms.
The system consists of a melt tank with a recirculating glycol loop carrying waste heat from generators to melt snow connected to a 3,700 gallon capacity water supply tank
A water decontamination and filtration unit purifies the water as it passes through the system before it is heated to 90°C and pressurized to 2000 psi by six heater-pump units.
A hose reel unit is then used to feed the main and return drill hoses down into the ice, with the entire operation orchestrated from a separate command and control module.
Dr Rack said: “We designed and built the WISSARD hot water drill as a containerized system to protect it from the elements, but it still had to be integrated with the work decks and science lab infrastructure and traversed over the ice shelf to reach the drill site.
“All the pieces of the system didn't come together until the testing phase in Antarctica in December. We were constantly racing the clock to get everything pulled together and shipped, assembled, and tested in time to traverse out to the site to accomplish the drilling.”
The team were able to draw on equipment and experience gained from the IceCube neutrino observatory at the Amundsen-Scott South Pole Station in Antarctica which was created using a hot-water drill.
Mr Rack said: “We benefited significantly by having access to some of the equipment and modules from the IceCube Project, especially the two 225 kW generators and the power distribution module.
“We also hired key personnel from the IceCube Project who played significant roles in designing the WISSARD drill and operating it in the field. Their experience helped us to build a system that worked well and allowed the drillers to do what they needed to do the first time it was used.”
With the bore hole completed the engineers will now handover to the science team but Dr Rack hopes the drill will be back in action soon.
He said: “We are hoping to go back to Subglacial Lake Whillans next season to drill at a number of sites to complete the original science plan for this project. There are proposals being submitted to use the drill at other locations, such as the grounding line of the Ross Ice Shelf to explore that subglacial environment.”
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