Anyone out there?

In December,a brace of 42 radio telescopes,known as the Allen Telescope Array,nestled in the shadow of Lassen Peak,California,came to life and resumed hopping from star to star in the constellation Cygnus,listening for radio broadcasts from alien civilisations. The lines are now open,but how long they will remain that way is anybodys guess.

These should be boom times for those seeking out aliens. Astronomers now know that the galaxy is teeming with at least as many planets as stars. Advanced life and technology might be rare in the cosmos,said Geoffrey W. Marcy,a professor in extraterrestrial studies at the University of California,Berkeley,but surely they are out there,because the number of Earth-like planets in the Milky Way galaxy is simply too great.

A simple howdy,a squeal or squawk captured by one of the antennas here at the University of Californias Hat Creek Radio Observatory would be enough to end our cosmic loneliness and change history,not to mention science. It would answer one of the most profound questions humans ask: are we alone in the universe?

Despite decades of space probes and billions of NASA dollars,there is still only one example of life in the universe: the DNA-based web of biology on Earth. In this field, said Jill Tarter,an astronomer at the SETI Institute,the number two is the all-important number. Were all looking for number two.

Politics and the recession have crimped astronomers budgets and left the institutes scientists with a kind of siege mentality. No federal funds have been spent searching for radio signals from extraterrestrials since 1993.

998,000 Stars to Go

The story begins with a young radio astronomer named Frank Drake,who pointed an antenna from the National Radio Astronomy Observatory in West Virginia at a pair of stars in 1960. In 1971,NASA held a workshop led by Dr Barney Oliver,from Hewlett-Packard,that concluded the best way to find extraterrestrials was with a $10 billion array of giant radio telescopes called Cyclops. In 1993,a NASA-sponsored survey for signals from 1,000 nearby stars was cancelled by Congress. With the help of friends like Oliver,Tarter and her colleagues took the search private. You didnt have to ask a priest or philosopher about life in the universe, Tarter said. She was in the first generation who could conduct experiments about it. A half-century and roughly 2,000 stars later,humanity is still officially alone.

Drake is undaunted,noting that there are 100 billion suitable stars in the galaxy. His personal estimate,based on an equation he invented in 1961,is that there are 10,000 technological civilisations in the galaxy,one per million stars. Ive known all along we have to look at a million stars, he said.

The Allen Array,which was designed to find Drake his million stars,is named after Paul G. Allen,the Microsoft founder and philanthropist,who put up $25 million to get the project going. It was to consist of 350 antennas but Allens contribution was only enough to build 42 antennas which started operating in 2007.

The project got a lift in 2009 when Tarter won a $100,000 prize for a talk on the subject. She began by saying,The story of humans is the story of ideas. It elicited a donation of valuable equipment from Dell and Intel.

But the recession and the cutbacks that followed wiped out the universitys funds to run the observatory. The Allen telescopes went quiet. An appeal for financing eventually brought in about $220,000. Now,the Air Force will pay for a share of the operations at the observatory,which costs about $1.5 million.

Welcome All Species

Early in December,when Tarter returned to Hat Creek,the antennas were majestically turning to a music only they could hear. The doormat read,Welcome All Species. Tarter takes great pride that she and her colleagues have never published a false alarm. She recalls one dramatic moment in 1998,when she and her colleagues were working at the observatory in Green Bank,West Virginia,and had a signal they could just not eliminate. Finally they figured out that they were actually receiving transmissions from the European SOHO satellite.

It was a real adrenaline pumping time, she added. I cant imagine what the real deal will be.