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increase our limited knowledge of how life can sustain itself in these extreme environments on our own planet and beyond.

Lake Vida, the largest of several unique lakes found in the McMurdo Dry Valleys, contains no oxygen, is mostly frozen and possesses the highest nitrous oxide levels of any natural water body on Earth

approximately six times saltier than seawater

average temperature is minus 8 degrees Fahrenheit

the brine harbors a surprisingly diverse and abundant variety of bacteria that survive without a current source of energy from the sun

Previous studies of Lake Vida dating back to 1996 indicate the brine and its inhabitants have been isolated from outside influences for more than 3,000 years.

the best analog we have for possible ecosystems in the subsurface waters of Saturn's moon Enceladus and Jupiter's moon Europa

collaborators

developed stringent protocols and specialized equipment for their 2005 and 2010 field campaigns to sample from the lake brine while avoiding contaminating the pristine ecosystem

expands our knowledge of environmental limits for life and helps define new niches of habitability

To sample unique environments such as this, researchers must work under secure, sterile tents on the lake's surface

The tents kept the site and equipment clean as researchers drilled ice cores, collected samples of the salty brine residing in the lake ice and assessed the chemical qualities of the water and its potential for harboring and sustaining life

analyses suggest chemical reactions between the brine and the underlying iron-rich sediments generate nitrous oxide and molecular hydrogen

may provide the energy needed to support the brine's diverse microbial life.

Additional research is under way to analyze the abiotic, chemical interactions between the Lake Vida brine and its sediment

investigating the microbial community by using different genome sequencing approaches

a gray plastic vessel, as long as a baseball bat, filled with water from Lake Whillans, half a mile below.

The bottle was hurried into a 40-foot cargo container outfitted as a laboratory on skis

Some of the lake water was squirted into bottles of media in order to grow whatever microbes might inhabit the lake

cultures could require weeks to produce results

When lake water was viewed under a microscope, cells were seen: their tiny bodies glowed green in response to DNA-sensitive dye. It was the first evidence of life in an Antarctic subglacial lake.

(A Russian team has reported that two types of bacteria were found in water from subglacial Lake Vostok, but DNA sequences matched those of bacteria that are known to live inside kerosene—causing the scientists to conclude that those bacteria came from kerosene drilling fluid used to bore the hole, and not from Lake Vostok itself

In order to conclusively demonstrate that Lake Whillans harbors life, the researchers will need to complete more time-consuming experiments showing that the cells actually grow

dead cells can sometimes show up under a microscope with DNA-sensitive

weeks or months will pass before it is known whether these cells represent known types of microbes, or something never seen before

t a couple of things seem likely. Most of those microbes probably subsist by chewing on rocks. And despite being sealed beneath 2,600 feet of ice, they probably have a steady supply of oxygen.

oxygen comes from water melting off the base of the ice sheet—maybe a few penny thicknesses of ice per year

When you melt ice, you’re liberating the air bubbles [trapped in that ice

That’s 20 percent oxygen

, lake bacteria could live on commonly occurring pyrite minerals that contain iron and sulfur

would obtain energy by using oxygen to essentially “burn” that iron and sulfur (analogous to the way that animals use oxygen to slowly burn sugars and fats).

The half mile of glacial ice sitting atop Lake Whillans is quite pure—derived from snow that fell onto Antarctica thousands of years ago.

contains only one-hundredth the level of dissolved minerals that are seen in a clear mountain creek, or in tap water from a typical city

a sensor lowered down the borehole this week showed that dissolved minerals were far more abundant in the lake itself

The fact that we see high concentrations is suggestive that there’s some interesting water-rock-microbe interaction that’s going on

Microbes, in other words, might well be munching on minerals under the ice sheet

will take months or years to unravel this picture

will perform experiments to see whether microbes taken from the lake metabolize iron, sulfur, or other components of minerals

will analyze the DNA of those microbes to see whether they’re related to rock-chewing bacteria that are already known to science.

Antarctica isn’t the only place in the solar system where water sits concealed in the dark beneath thick ice. Europa and Enceladus (moons of Jupiter and Saturn, respectively) are also thought to harbor oceans of liquid water. What is learned at Lake Whillans could shed light on how best to look for life in these other places