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Thursday, 17 January, 2002, 20:09 GMT
Alien life could be like Antarctic bugs
Mahaney, Univ Ontario
Prof William Mahaney in Antarctica's ice-free dry valleys
By BBC News Online science editor Dr David Whitehouse

Scientists have found living microbes buried far deeper than ever detected before in Antarctica's ice-free dry valleys.

[This] opens up the possibility of life on Mars and the possible positions within a soil where it might be found

Prof William Mahaney and colleagues
The nature of the harsh environment once again raises the possibility of similar organisms existing on other worlds in our Solar System.

The researchers found fungi and a common species of Penicillium bacteria at two sites in salty soil layers more than three to eight centimetres (1 - 3 inches) beneath the frozen Antarctic surface.

It is believed that the cold, dry, valley soils of the White Continent formed under conditions very like those of past and present Mars, "where similar weathering could occur and possible microbial populations may exist", the researchers say.

Another team of scientists announced on Wednesday that they had found hydrogen-consuming microbes 200 metres (660 feet) down a hot spring in Idaho in the US. The unusual metabolism of these organisms is also said to suggest how lifeforms could survive on Mars and other planets or moons.

Glacial deposits

The Antarctic dry valleys come closer to the present-day Martian climate than anywhere on Earth.

The mean annual temperatures in the Quartermain Mountains hover at minus 30 degrees Celsius to minus 35 degrees C - like a warm day on Mars. Precipitation is practically zero.

Finding the microbes so deep underground in this region was a surprise. Professor William Mahaney of York University, Ontario, Canada, told BBC News Online that when he and his colleagues explored the region they were not thinking about Mars.

Microbes, Univ Ontario
Hardy microbes thrive in the supercold
Glaciers deposited tills, or rock debris, in this region about 23 million years ago, when the Antarctic climate was warmer and wetter than it is now.

The team's first plan was to determine the age of the ancient soils in the region; they focused on soil layers they dated at between 10 and 15 million years old.

"We went to the iron-rich layers, where we thought we'd find lots of microbes, because microbes need iron," Professor Mahaney says. "We sampled the lower-down high-salt layers, where we thought we would find few micro-organisms. We found just the opposite.

"We found microbes in soil with 3,000 parts per million salt concentrations. That's like vodka. That's so much salt there that the temperature can drop to minus 56 degrees C before there's frost bite."

Abundant and well formed

The University of Arizona's Professor Victor Baker said: "These (supercooling) processes are not fully understood on Earth, but the fact that they occur in Antarctica shows the possibility that they also might occur on Mars.

"We also found that these microbe colonies are not just a one-shot occurrence," Professor Mahaney says. "We found abundant, well-formed, long-lived fungi colonies at two sites in two organic carbon-poor layers between three cm and eight cm (1 - 3 inches) below the surface pavement.

"The strange thing is, we found several colonies of Beauveria bassiana - fungi that thrive on insects. The colonies may have been there longer than centuries, maybe millennia, maybe since the last Ice Age - I have no idea how long. So the question is: what do these well-developed colonies live on?"

Scientists first discovered algae, fungi and bacteria growing inside porous sandstone and surface pavement in the Antarctic dry valleys more than 20 years ago. But these organisms go deeper, occupying what were thought to be regions where life could not survive.

The researchers, writing in the journal Icarus, say: "We believe that our investigation of parts of the Antarctic yields valuable information about soils and microbial life that may bear significantly on future manned and unmanned missions to Mars."

They add: "It appears that tills have been emplaced on Mars under environmental conditions approximately similar to those occurring in the dry valleys study site, and that the time scale of 10 million years may apply to both areas."

The BBC's Sue Nelson
"These microbes require no sunlight"
See also:

16 Jan 02 | Sci/Tech
Tough bugs point to life on Mars
23 Jun 00 | Sci/Tech
Water may flow on Mars
26 Jun 98 | Sci/Tech
'Ice bacteria' clue to life on Mars
12 Feb 99 | Sci/Tech
Martian 'bacteria' matched to Earth
23 Jun 00 | Sci/Tech
What now for Mars?
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