E.T.'s in the Shadow Biosphere

Scientists at the British Royal Society are meeting this week to discuss whether the search for extra-terrestrial life should be focused not in outer space but on the possibility that alien micro-organisms could be hiding out here on Earth. The conference's audience will include representatives from NASA, the European Space Agency and the UN Office for Outer Space Affairs and will include a session led by Lord Rees, President of the British Royal Society and Astronomer Royal.

Addressing the meeting to mark the 50th anniversary of the Search for Extra-Terrestrial Intelligence (SETI) program, Professor Paul Davies, an award-winning Arizona State University physicist will refer to the fact that life has appeared more than once on Earth as evidence that it must exist elsewhere in the Universe.

Professor Davies claimes that there are “weird” microbes belonging to a completely separate tree of life, called the “shadow biosphere”, that could be present in isolated ecological niches. These are environments where it's difficult for life as we know it to take hold including deserts, scalding volcanic vents, the dry valleys of Antartica or salt-saturated lakes.

One theory is that places heavily contaminated with arsenic, such as the Mono Lake in California, might support forms of life that use arsenic in the same way that other life forms use phosphorus.

Not all are convinced by the “shadow biosphere” concept but in terms of extra-terrestrial research it may make more sense than waiting for them to respond to us:  with the advent of digital communications, the amount and strength of radio waves sent out from the Earth has greatly diminished from previous decades--rendering humankind almost "undetectable" to anyone listening for us in space.

Image:  "Mono Lake" by goingslo via Flickr courtesy of Creative Commons Licensing.