Alien hunters 'should also seek weird life'
By Tom Leonard in New York
Last Updated: 2:31am BST 10/07/2007
The hunt for extra-terrestrial life should encompass what experts call "weird life", according to a committee of scientists in the US.
An artist's impression of the European Space Agency's Huygens spacecraft entering the atmosphere of Titan in 2004. Scientists believe Saturn's largest moon is a promising source of weird life
The Huygens spacecraft visited Titan in 2004. Scientists believe the moon is a promising source of weird life
Nasa selects planets and moons with hints of water for its exploratory missions.
But according to the scientists, who have written a report for the National Research Council in the US, other chemicals such as ammonia or methane could also support life.
So-called "weird life" or organisms that lack DNA or other molecules found in life on Earth could exist, the scientists say.
For example, while DNA uses phosphorus in its backbone, it might be possible to build a backbone out of arsenic.
Titan, one of Saturn’s moons, has been singled out as a particularly promising source of weird life.
Michael Meyer, the senior scientist responsible for Nasa’s Mars exploration programme, said: "It’s going to help us a lot to make sure we go exploring with our eyes wide open."
"The committee’s investigation makes clear that life is possible in forms different from those on Earth," the scientists conclude in the study, titled The Limits of Organic Life in Planetary Systems.
The report also urged that the hunt for weird life be extended to Earth itself, as some examples may exist on the ocean floor, said the scientists.
"There’s much about Earth life we don’t understand", said John Baross of the University of Washington, who chaired the committee.