- A subglacial lake is a body of liquid water located in between an ice sheet and the continental land mass. The water remains liquid because the ice sheet above the water acts as an insulator and traps geothermal heat from the Earth’s crust.
- 379 lakes are thought to exist beneath the Antarctic ice sheet.
- Many of the lakes are interconnected with water flowing from one lake to another other via streams and wetlands.
- Some lakes like Lake Vostok under the East Antarctic Ice Sheet retain water on the order of the 10,000 years, while others like Mercer Subglacial Lake only retain water on a decadal scale.
- The presence of liquid water beneath the ice sheet can affect its movement, therefore understanding a subglacial waterway is crucial to understanding ice sheet stability.
- Subglacial lakes are permanently cold and dark environments that could add to our understanding of the evolution of life in these extreme environments on earth and other celestial bodies.
Mercer Subglacial Lake
- Lake Mercer is about 4,000 feet below the ice surface (Just over the height of 3 Empire State Buildings).
- Lake Mercer is considered to be an active lake that goes through periodic filling and draining cycles, retaining its water on only a decadal scale.
- Lake Mercer rests at the confluence of the Whillan’s Ice Stream that flows from West Antarctica and the Mercer Ice Stream that flows from East Antarctica.
- 25 percent of Lake Mercer’s water flows from the East and 75 percent flows from the West.
- The water present in Lake Mercer is thought to flow directly to the Ross Sea, making the lake a direct link between the unexplored subglacial environments of Antarctica and the global oceans.
- SALSA has 11 principal investigators from eight different institutions across the US.
- During the Antarctic summer of 2018-2019, the SALSA camp will be home to about 50 scientists, drillers, and support staff. They will sleep, eat, and work on the ice cover above Subglacial Lake Mercer for about three weeks time.
- A hot water drill will melt through the ice to the Subglacial Lake Mercer two-thirds of a mile below the surface.
- This is only the second time scientists have been able to study one of the planet’s last frontiers. The first occurred from 2009-2014 during the WISSARD project.
- After an estimated 3-4 days of drilling, the science team will have about 8 days to collect water and sediment samples and conduct experiments in the SALSA field labs.
- Water and sediment samples will be retrieved from the lake by lowering sampling devices attached to a winch carefully through the hole in the ice into the estimated 20m deep water column.
- Robotic tools will capture 4k video and explore the physical characteristics of the lake cavity, while other instruments will collect physical and chemical measurements directly in the water column.
- Building from what WISSARD started, the project is likely to discover new types of microbial life in the lake water and sediments, will provide new knowledge on subglacial carbon cycling, will uncover new information on earth’s history and will provide information on the importance of the flow of subglacial water under the surface of Antarctica.
Hot Water Drilling
- Drilling operations are conducted and monitored from a command and control module.
- Water is supplied by melting snow in a melt tank. From there it is stored in a 4,500 gallon holding tank.
- The drill hole contains enough water to fill 62,400 8 oz. drinking glasses.
- The hole we drill is 4,000 feet deep, that is so deep we could stack three Empire State buildings and still be 250 feet away from the bottom.
- The drill puts as much energy through a spray nozzle the size of a pencil as a railroad locomotive.
- When drilling, the amount of the ice we melt weighs 500,000 lbs.
- 225 k Watt generators supply power for drilling, camp, and science operations (they generate enough energy to power Scott’s Base, the New Zealand research station).
- The water used for drilling is heated by 6 Alkota power units (984 kilowatts of thermal energy), all housed in two, 40 foot shipping containers.
- A third shipping container holds the main hose reel, return water system, instrumentation manifold and hose washing system.
- A fourth container houses the clean access filtration unit than uses UV radiation and filtration to kill and remove micro and sub-micron particles (biotic and abiotic).
- As part of clean access, all instruments and cables are washed with 3% hydrogen peroxide.
- The top of the borehole is protected by a UV radiation collar through which all instruments and cable travel.
- In December 2017 three tractors, each capable of pulling 100,000 lbs., drove 650 miles from McMurdo to Lake Mercer.
- The journey took two months and carried an estimated 1,000,000 pounds of material.
- The tractors drive at an average speed of 7mph and pull 35,000 gallons of fuel.
- The traverse successfully dropped off drilling equipment, science labs, and several camp structures at the study site in January 2018.
- In November 2018, a different traverse will shuttle remaining equipment to Lake Mercer and prep the camp site and runway for scientists to arrive in December.