NASA steps up search for alien life forms on Mars

The US National Aeronautics and Space Administration is stepping up its hunt for alien life, but not the little green men so beloved of science fiction. "We will look for the creatures that really count, the microbes," explained Dr David Morrison, a director at NASA's Ames Research Centre.

NASA has put $20 million into a new Astrobiology Institute and is involved in a number of other related programmes. Astrobiology is a new multi-disciplinary research effort.

"It is simply the study of life in the universe," Dr Morrison said, including the origins and evolution of life here, future life and life on other worlds. "The premise is that the space programme has reached the point where it can begin to provide answers to these questions," he said. Dr Morrison organised a session at the American Association meeting that brought together a number of scientists working in this area. The strategies used to search for extraterrestrial life would mirror those already employed here, he said.

Recent discoveries of microbial life in deep ocean sediments, at boiling point temperatures next to undersea volcanic vents and in rocks drilled from miles below our feet had given us new places to consider looking for aliens, said Dr Jack Farmer, professor of geology at Arizona State University.

It modified our view of where to look for life on Mars and how to find it. A number of soil sample return missions to Mars are planned starting in 2003 with martian rocks and under-surface samples likely to be retrieved during a 2005 mission, he said.

There are more ambitious plans however, including a mission to study the Jovian moon, Europa, which appears to have liquid water - viewed as essential for life - hidden under a frozen surface. Early ideas, he said, included the possibility of sending a submarine to melt through the ice before exploring the underwater realms.

Dr David Des-Marais, also of the Ames Research Centre, said there was particular interest in five planets and moons in this solar system. The search would continue for life at the limits on earth but also on Mars, Venus, Europa and Pluto's partner moon, Charon.

Another Ames scientist, Dr Jonathan Trent, discussed studies of the "physical and chemical limits for life". Work on earth had shown clearly that microbial life could adapt to the most extreme conditions. Humans were also at the point where we could begin exporting life to new worlds, said Dr Emily Morey-Holton, chief of the gravitational research unit at Ames.

Deciding whether to send humans to Mars depended on three questions: do we need to do it, can we afford to do it and what are the safety risks, Dr Morrison said. If satisfactory answers to these questions were found then such an endeavour might take 10 years to accomplish.