An airborne survey of a presumably dry Antarctic valley revealed a stunning and unexpected interconnected subsurface briny aquifer deep beneath the frozen tundra, a finding that not only has implications for understanding extreme habitats for life on Earth, but the potential for life elsewhere in the solar system, particularly Mars.
The briny liquid -- about twice as salty as seawater -- was discovered about 1,000 feet underground in a region known as Taylor Valley. The aquifer is widespread, extending from the Ross Sea's McMurdo Sound more than 11 miles into the eastern part of valley. A second system was found connecting Taylor Glacier with the ice-cover Lake Bonney.
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But the survey, which covered 114 square miles, may have just uncovered the proverbial tip of the iceberg.
"It suggests that this ecosystem is extensive and connected. There could be a very, very large subsurface habitable environment throughout the Antarctic regions," Ross Virginia, an ecosystem ecologist at Dartmouth College, told Discovery News.
"One of the big questions now is is this finding regionally specific, or are there many locations in Antarctica where we have conditions that have created these subsurface environments for life," Ross Virginia, an ecosystem ecologist at Dartmouth College, told Discovery News.
In a paper published in Nature Communications, lead researcher Jill Mikucki, with the University of Tennessee, and colleagues note that while few subsurface aquatic environments have been sampled, all were found to be teeming with life.
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Earlier this month, scientists using temperature and humidity measurements taken by NASA's Mars rover Curiosity realized that conditions were right for salty liquid water to exist close to the planet's surface. On Mars, perchlorates in the soil lower the freezing temperature of water, a different chemistry than what exists in Antarctica.
"The subsurface aquifers that we've been looking at in the (Antarctic) are potential analogs to understanding Mars systems," Mikucki told Discovery News. "We still have a lot to learn about these dry valley aquifer systems, but they appear to be related to climate changes."
Curiosity and other missions have turned up ample evidence that Mars, which is now a cold and dry desert, was once flush with water. What happened to the water is still a mystery.
To survey the Antarctic subsurface, scientists used an instrument known as transient electromagnetic sensor to generate a strong, ground-penetrating electromagnetic field. Liquids – particularly salty liquids – are more conductive than rock, soil and ice, giving scientists to ability to differentiate subsurface materials.
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Scientists have used similar instruments in the past, but only on the ground. That provided enough of a hint of subsurface water network for the National Science Foundation to approve a trial program flying the sensor on a helicopter.
Researchers now hope to conduct a more extensive aerial survey.