SETI has investigated a billion potential signals from alien beings since the project began almost 50 years ago. None has so far turned out to be ET, but that hasn鈥檛 stopped the search for extraterrestrial intelligence, which is about to expand dramatically.
First up is SETI@homeII, due for launch early next year. The program is a direct descendant of SETI@home, the screensaver that uses your humble PC鈥檚 down time to search data from the giant Arecibo radio telescope in Puerto Rico (see below) for signs of alien life.
SETI@home began three years ago, and proved too popular for its own good. The University of California, Berkeley, the project鈥檚 home, didn鈥檛 have the bandwidth to send out data fast enough and frustrated alien seekers couldn鈥檛 get connected. 鈥淲e expected 100,000 people to join the project. We鈥檙e closing on 4 million,鈥� says Eric Korpela, a SETI scientist at Berkeley. To help prevent future traffic jams, SETI@homeII will cut down traffic by allowing users to do more in-depth analyses such as searching for single intense pulses, which uses a lot of computing power.
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Besides looking deeper into the data, SETI is also gearing up to search a bigger chunk of the sky with a new radio signal analyser called SERENDIP V, due to come online in the next 12 months. It will be used with Arecibo, as well as with the Parkes radio telescope in Australia 鈥� extending the search to the southern skies for the first time.
And while SETI@homeII attempts to survey as much of the sky as possible for alien signals, targeted searches will also expand over the next few years. These will focus on other solar systems that have a good chance of being home to cosy life-sustaining planets like our Earth. In 2005, the Allen Telescope Array, the first purpose-built telescope for alien searches, will come online in California. 鈥淚t will revolutionise our search for extraterrestrial intelligence,鈥� predicts origins of life expert Chris Chyba of the SETI Institute in Mountain View.
With 350 dishes, the ATA covers a total area of 10,000 square metres, and will be better at detecting signals from alien civilisations rather than just monitoring astrophysical phenomena. It will also be much faster than current searches, hopefully examining radio signals from around 100,000 stars in its first decade.
And if it finds something? At SETI, preparations for first contact have already begun. At the World Space Congress in Houston this October, it will introduce the Rio scale, an index a bit like the Richter scale for earthquakes, but designed to inform the public how likely it is that an incoming signal will turn out to be for real. It will run from 0 for a totally bogus hoax, to 1, meaning a confirmed and highly credible signal.
SETI has even set up a Post-Detection Committee, including astronomers, computer scientists and sociologists ready to spring into action should we make contact. Until then, the committee is considering weighty issues such as how and when to inform national authorities, and whether it should try to stop people replying to the signal.
Palaeontologist Simon Conway Morris of Cambridge University is adamant on this point. The fact that aggression has arisen independently in so many species on Earth suggests that the trait will be found wherever life is, he says. 鈥淐onflict is inherent to most successful species. I鈥檇 suggest that if the telephone rings, put it down straight away.鈥�
That鈥檚 if it鈥檚 not already too late. For all this searching, we can鈥檛 rule out the possibility that intelligent aliens are already in our own backyard, says Jill Tarter, Director of the Centre for SETI Research at the SETI Institute in Mountain View. 鈥淭hey could be here. I don鈥檛 mean they are abducting people off the street, or landing on the White House lawn. But we have so poorly explored our own Solar System, there could be probes here that we don鈥檛 know about,鈥� she says.
