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A Glacial Quest For
Alien Life Forms

By Anne McIlroy
The Globe and Mail
6-14-4
 
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.
 
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.
 
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.
 
"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.
 
"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."
 
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.
 
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.
 
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.
 
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.
 
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.
 
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.
 
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.
 
"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."
 
Space scientists have long been intrigued by the possibility of finding extraterrestrial life forms in ice-covered worlds far from Earth, especially on Europa.
 
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.
 
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.
 
- Anne McIlroy is The Globe and Mail's science reporter
 
© 2004 Cable News Network LP, LLLP. http://www.cnn.com/2004/TECH/space/06/14/egypt.ancientcemetery.ap/


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