- The discovery of millions of ancient, ultratiny microbes
3,000 metres deep in a Greenland glacier suggests that similar hardy species
may live in ice elsewhere in the solar system, researchers say.
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- Ice has been detected in the northern latitudes of Mars
and on Europa, one of Jupiter's moons, but many scientists pursuing the
search for life beyond Earth have focused on the oceans that may lie beneath
that ice as a possible home for extraterrestrial organisms.
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- New research presented recently at a conference in New
Orleans suggests that the ice itself may be a fertile hunting ground. The
microbes in the Greenland glacier are at least 120,000 years old, and may
be several million years old.
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- "People in astrobiology are of course interested
in extreme environments. If you can find something on Earth that survives
in these conditions, then we know something could have survived if it exists
on Mars," said Jean Brenchley, a microbiologist at Penn State University
and one of the scientists who made the Greenland discovery.
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- "We humans make the assumptions that all life is
going to require liquid water," she said. But some researchers have
theorized there are actually tiny veins of water in ice. "Even though
we think of an ice cube as frozen solid, within that there might be regions
that might be liquid, and of course a micro-organism doesn't need a lot
of area."
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- Scientists, including Canadians working in the High Arctic,
have found bacteria in glaciers before. In 1999, researchers found bacteria
buried deep beneath the Antarctic ice sheet, just above an isolated subglacial
body of water named Lake Vostok.
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- But the ice above the lake may have melted and reformed,
making it more likely that micro-organisms would be found there. That is
not the case with the Greenland ice core, although the researchers found
far greater numbers of microbes there, and much tinier ones than those
detected in the other samples.
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- As well as helping to set the limits for life on Earth
and elsewhere in the universe, they say, their find may yield new insight
into how bacteria can survive for thousands or even millions of years.
The team found new species of tiny microbes, about a 10th the size of the
common gut bacteria Escherichia coli, or E. coli, deep in the Greenland
ice core.
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- Some of the tiny bacteria appear to be shrunken versions
of a larger species. "They looked like a bigger cell that had been
on a severe diet," Dr. Brenchley said.
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- But others, when grown in a lab, produce equally tiny
offspring. The researchers need to do more work to find out if both phenomena
are part of a survival strategy for living deep beneath the ice.
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- The researchers were unable to tell if the bacteria were
getting nutrients, producing waste or any of the other signs of ordinary
microbial life, or whether they were simply trapped in ice, carried down
from the top of the glacier by the flow of the ice, or up from the permafrost
and sediment below.
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- This is a key question with implications for the search
for extraterrestrial life, said Martin Sharp, a glaciologist at the University
of Edmonton who has found microbes in glaciers in Switzerland and on Ellesmere
Island in the Canadian Arctic. Like Dr. Brenchley and his colleagues, he
is working on proving whether glacial micro-organisms are part of a viable,
functioning ecosystem.
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- "Sure, it could be an analogue for Europa or Mars,
but until you demonstrate that these things really do function under these
conditions, then it is an open question as to whether it is really helpful
or not."
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- Space scientists have long been intrigued by the possibility
of finding extraterrestrial life forms in ice-covered worlds far from Earth,
especially on Europa.
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- The ice surface of Europa is streaked with reddish-brown
cracks, possibly caused by micro-organisms suspended in the ice. It turns
out that the infrared signature of the ice is similar to that of microbes
on Earth.
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- Astrobiologists are also encouraged by data collected
from the Odyssey spacecraft circling Mars in 2002 that strongly suggested
there is ice just under the dusty surface of the planet at higher latitudes.
The two U.S. National Aeronautics and Space Administration rovers now on
the Red Planet are nowhere near the areas researchers believe are covered
by ice. NASA is planning a mission in 2007 that will send a lander to the
suspected icy region.
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- - Anne McIlroy is The Globe and Mail's science reporter
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- © 2004 Cable News Network LP, LLLP. http://www.cnn.com/2004/TECH/space/06/14/egypt.ancientcemetery.ap/
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