Divining Water on Europa

Exotic Microbes Discovered near Lake Vostok

Scientists have discovered a microbial world hidden deep beneath the frozen Antarctic ice that could help them learn more about how life can survive under extreme conditions on other planets or moons.

BASED ON A NASA/AMES PRESS RELEASE

December 10, 1999: Scientists have discovered a microbial world hidden deep beneath the frozen Antarctic ice that could help them learn more about how life can survive under extreme conditions on other planets or moons.

Their findings are featured in a research paper co-authored by Dr. Chris McKay, a planetary scientist at NASA Ames Research Center, Moffett Field, CA, which will be published in the Dec. 10 issue of Science magazine. Co-authored by a multi-disciplinary science team, the research paper entitled "Geomicro-biology of Subglacial Ice Above Lake Vostok, Antarctica," analyzes the ice above Lake Vostok, a huge freshwater lake buried deep below the East Antarctic ice sheet.

Above: In 1993, altimetric and radar data were used to trace this outline of Lake Vostok, located about 1000 miles from the South Pole. Image used is copyrighted by the Canadian Space Agency. More Information from Caltech-JPL.

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"Microbes within the liquid water habitat of Lake Vostok may shed light on the viability of life in similar harsh environments beyond Earth, such as in the frozen ocean subsurface on Jupiter's moon, Europa, "McKay said. Galileo spacecraft results imply that a subsurface ocean could exist on Europa.

The research team tested samples from the ice 3,590 meters below Vostok Station, and found diverse colonies of microbes. Scientists say this is significant because the lake has been isolated from the usual sources of atmospheric-derived energy, such as photosynthesis, for millions of years.

"How the bacteria get energy (to survive) is an important question," McKay said. "The lake could be an analog to sub-ice Europa or subsurface Mars where conditions are similar."

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Scientists believe ice is a good environment for primitive bacteria. The bacteria need less food because it's cold, and its metabolism slows down, somewhat like a hibernating bear's. Another finding was that DNA extracted from the microbes present in the team's Lake Vostok sample indicated the presence of only a few subgroups of known bacteria, coupled with low overall microbial diversity.

"It's what you'd expect, not teeming with rich life," McKay said. The team also found signs of bacterial life in the ice core and detected metabolic activity in some of the bacteria by measuring the bacteria's respiration rates during incubation.

Fractured terrain on Europa -- image credit: Galileo

Scientists said the sampled Vostok glacier ice also suggested that the lake water derived from a mixture of melted ice from both glacial and interglacial periods, deposited there approximately one million years ago.

Although the thickness of the ice on Europa is not known, scientists think that tidal forces could form cracks extending to the surface. Under the thin ice, conditions may be similar to the conditions at Lake Vostok. "If a similar ice layer is present under the surface of Europa's icy oceans, it may also harbor life," said McKay.

Left: Fragmented chunks of ice on Europa, similar in appearance to those seen in Earth polar seas during a springtime thaw. It's possible that Europa and Lake Vostok share a number of remarkable properties, including a kilometers-thick covering of ice over liquid water and an environment where life may have developed along unique evolutionary paths, [more information]

The research team included the paper's lead author, Dr. John Priscu, and others from the departments of Biology, Earth Science and Physics at Montana State University, Bozeman, MT. Other researchers were from the department of Geology, the University of Alabama, Tuscaloosa, AL, and the U. S. Geological Survey, Reston, VA.

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Related Stories:

Divining Water on Europa -- Sep 9, 1999. Circumstantial evidence for water on Europa mounts as JPL scientists try an ingenious experiment to find hexagonal water-ice crystals on the frigid surface of Jupiter's iciest moon.

Astrobiologists To Hunt Small Game in Siberia -- Jul. 27, 1999. Arctic permafrost may hold clues to life on other worlds

The Frosty Plains of Europa -- Dec. 3, 1998. As Galileo returns new images of Europa, NASA scientists prepare to study samples from a potentially similar environment here on Earth.

Clues to possible life on Europa may lie buried in Antarctic ice -- Mar. 5, 1998. Exotic microbial forms turn up in ice above Antarctica's Lake Vostok.

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