Aliens can't hear us, says astronomer

Human beings are making it harder for extraterrestials to pick up our broadcasts and make contact, the world's leading expert on the search for alien life warned yesterday.

At a special meeting on the search for extraterrestrial intelligence (Seti), the US astronomer Frank Drake – who has been seeking radio signals from alien civilisations for almost 50 years – told scientists that earthlings were making it less likely they would be heard in space.

Astronomers assumed that a standard technique for any alien intelligence trying to pinpoint other civilisations in the galaxy would involve seeking signals from TV, radio and radar broadcasts, Drake told the meeting at the Royal Society in London.

Scientists on Earth have been using this method, without success so far, to find evidence of intelligent aliens. The theory is that elsewhere in the galaxy other civilisations would probably be doing the same.

An example of this interstellar eavesdropping is dramatised in the Jodie Foster film Contact. Based on a novel by the US astronomer Carl Sagan, it tells the story of an alien civilisation that makes contact after picking up TV broadcasts from Earth.

"The trouble is that we are making ourselves more and more difficult to be heard," said Dr Drake. "We are broadcasting in much more efficient ways today and are making our signals fainter and fainter."

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