More than 95 percent of the surface of Antarctica is covered with a sheet of glacial ice up to 5 kilometres thick and two million years old. Consequently, nearly all of the ground under the glaciers has been literally out of sight for millennia.
Drilling hidden Antarctic lake
But by using ice-penetrating radar and seismic studies, researchers have been able to map much of this terra incognita. In the process, they have found at least 70 bodies of water nestled between the ice sheet and the Earth. The largest of these lakes, Vostok, has become a hot scientific topic because of the possibility that it might hold life in the form of microorganisms.
Lake Vostok lies beneath Russia’s Vostok research station. The lake is huge, with an area about that of Lake Ontario, but twice as deep. However, little else is known about the lake because it is beneath 3.6 kilometres of ice.
How giant hidden lakes formed beneath 3.6km of ice
It is this ice that creates and preserves Vostok and the other Antarctic lakes. As the glaciers’ own weight presses down, ice at the bottom melts under the pressure and collects in depressions. The glaciers also form an insulating lid against evaporation. Hot springs that might exist at the bottom of the lakes would prevent them from ever freezing over.
That microorganisms might live in Antarctic lakes seems improbable, though not impossible. Life has been found virtually any place on Earth that has liquid water and some energy source.
But Lake Vostok represents perhaps the most extreme environment in which to find life. If no hydrothermal vents exist to pump nutrients into the lake, food for microorganisms could come only from what is trapped in the glacial ice in contact with the lake water. Also, the lake
is being squeezed by the glacier above up to 340 times the atmospheric pressure at sea level. This compression wrings out of the water nearly all the gases needed for respiration, possibly leaving lake life without a breath.
Similarities to conditions on Jupiter’s Moon Europa
With such hostile conditions, Lake Vostok resembles Jupiter’s satellite Europa, which very likely has an ocean under its thick crust of ice. The presence of life in Vostok would suggest that it could also exist in Europa’s also frigid depths.
A team of scientists studying Vostok has already drilled to within 120 metres of the top of the lake. However, concerns about contaminating the pristine water, which has not been open to the air for perhaps two million years, have delayed further drilling. But when these technical
problems are solved and scientists eventually do punch their way in, they will find an alien world more like another planet than anywhere else on Earth.
The discovery of living microbes just above a hidden freshwater lake 3.6km deep in the frozen Antarctic extends the range of extreme conditions under which life is known to survive.
The finding, which researchers say almost certainly indicates there is a thriving community of microscopic creatures in the ancient, pristine lake, buoys hopes that life may exist elsewhere in the solar system. It also
provides some clues about how and where to start looking.
“Our results extend the possible limits for life on Earth and elsewhere in the Universe,” said David Karl of the University of Hawaii, lead researcher on one of three studies presented in the Dec. 10 issue of the journal Science. “With each discovery of life in another extreme Earth environment we learn that much more about microbial adaptation, and survival and physiological strategies for life.”
The extreme conditions of the hidden Lake Vostok
In a spot nearly 10 times as far down as the Empire State Building is tall, below an Antarctic glacier, lies what researchers believe to be a natural reservoir of fresh water known as Lake Vostok. It is deeper than Lake Tahoe and has an ice-locked “surface” that spans an area as big as New Jersey.
Researchers say Vostok, named for the Russian research station that sits above it, is the largest of nearly 80 sub-Antarctic lakes that have been mapped by airborne radio sounding. It has been known for two decades, and the recent discovery is a milestone during a years-long suspicion that there might be life trapped in the lake.
Intense pressure from the overlying ice generates heat which, combined with geothermal heat from below, is thought to keep Vostok’s million-year-old water in a liquid state. The ice also serves as an insulating blanket.
Some 120 meters (393 feet) above the lake rests the lower end of the deepest ice core ever drilled — 3,623 meters (11,886 feet) below the frigid surface. There, in freshwater ice that researchers think has migrated upward from the lake, a community of microbes — extremophiles that define their own term — thrive in some of the harshest conditions imaginable.
“There’s a first principle among microbial ecologists that states: ‘Where there’s water there’s life,'” said Warwick Vincent, a professor of biology at Laval University, Canada. “Lake Vostok is the ultimate test of this principle in one of this world’s most hostile places. These new discoveries imply that the ‘life everywhere’ adage will once again prove correct.”
Extreme forms of life found in ice just above lake
The newly discovered microbes have gone about their business of living sans any contact with the outside world for millions of years. But after doing DNA analysis, a team led by John Priscu of Montana State University said the little critters are similar to modern-day organisms, including one called a proteobacteria. “Our research shows us that the microbial world has few limits on our planet,” Priscu said.
Vincent, who was not involved in the research, agreed with the other русское порно researchers in saying it appears the lake itself has “all the ingredients for an active microbial ecosystem.”
It may be a while before that theory is proved, however. Drilling was stopped four years ago to prevent introducing anything that might contaminate the water. Delegates from several nations met in September to decide whether and how to explore the lake, but no firm proposal has been accepted.
Regardless, the discovery shows that an extremely cold, dark environment that is cut off from a ready supply of nutrients can still support life. Sealed off from the sources of energy most other known organisms survive on, it seems the Vostok microbes live off things deposited long ago.
Earth life in such extreme conditions enhances the propects of life on nearby moons
The fact that organisms have adapted to living in such harsh conditions bolsters the expectation that extraterrestrial life may be waiting to be discovered right here in our solar system. Jupiter’s ice-covered moons Europa and Callisto, both thought to contain large oceans, have emerged in recent years as two of the most likely candidates.
Evidence shows that the massive gravity of Jupiter creates “tidal pumping,” a pull on the moons, that might generate heat within. Europa, about the size of Earth’s moon, has a surface temperature of minus 260° Fahrenheit, but the tugging of Jupiter’s gravity may well create enough warmth to keep large parts of Europa’s ocean liquid.
“Conditions on Europa are likely similar to those of the ice covered lakes, but may not be analogous,” Karl said. “If Europa has an internal energy pump, either through hydrothermal systems or via tidal pumping, then life may be better off than in Lake Vostok where microbes may be surviving off carbon and energy deposited there a million years ago.”
Vincent, the Canadian biologist who also chairs the Canadian Committee for Antarctic Research, expressed both optimism and caution regarding the search for extraterrestrial life.
“The chemistry of the waters of Europa and Callisto appears to be very different relative to that in Lake Vostok, “For example, these vast oceans (the largest in the solar system) are salty while all the evidence, including these most recent lake-ice analyses, shows that Lake Vostok is freshwater.”
Testing for life on Jupiter’s Moons
Scientists say convincing evidence of life on Europa may not come until robotic explorers venture below the surface.
A mission, the Europa Ice Clipper, is on the drawing boards. It would be a flyby mission designed to obtain samples of Europa’s subsurface by dropping hollow copper spheres onto the icy surface. A “hydrobot” would map the undersea terrain and look for life. The samples would then be returned to Earth. No date is set for launch. The recent hunt for life in the Antarctic is expected to help build such future probes.
“I think that the Vostok experience may help in the design of biochemical and molecular probes for the search for life elsewhere,” Vincent said. “It will also help in the design of sampling technologies, not only in terms of the challenge of sampling deep ice under conditions of extreme cold but also in the development of environmentally friendly technologies that will reduce any lasting negative impacts of human exploration throughout the solar system.”
Whatever we might find on Europa, Callisto, or any other body in the solar system won’t likely look like any conventional alien, experts agree. Don’t even expect a small fish, they say. But the mere discovery of simple microbial life elsewhere would hint at the likelihood that life is a far more common occurrence in the Universe than we humans might have once thought.
