SETI, or the Search for Extra Terrestrial Intelligence, is a collective designation for a series of experiments designed to ascertain whether or not there is intelligent, communicative life in outer space. The search has been carried out, mostly, by trying to detect radio transmissions, deliberate or non-deliberate, from such putative extraterrestrial intelligences. The underlying basis of this search was the discovery that radio waves, artificial or natural, are capable of travelling across space. What this meant, of course, was that if there were any radio-capable intelligence within radio reach of Earth, such intelligences could be (at least) detected.
The 1st SETI experiment was Project Ozma, which was organised by Frank Drake, then at Cornell University, Ithaca, New York, in 1960. Using a 26 metre radio telescope (a device designed to receive, analyse and transmit radio waves to and from outer space, he and his team carried out a search of 2 neighbouring stars, Tau Ceti and Epsilon Eridani. The information that was gathered from this experiment was not, from a SETI point of view, of any great importance.
In 1963, the Ohio State University set up a radio telescope 110 metre wide, 150 metres long and 21 metres high (based on a design suggested by John Kraus, one of the university’s professors), called Big Ear, and began the world’s first continuous SETI program.
In 1971, the US government funded a study, under the auspices of the National Aeronautics and Space Administration, NASA, which proposed the setting up of a telescopic array of 1500 dishes. Named Project Cyclops, the proposals were never implemented but they did give a direction to the future of SETI investigations.
In 1974, in what was essentially a symbolic gesture, it was Earth’s turn to send out a call, rather than waiting to recieve one. On 16th November, at a ceremony to commemorate the redesigning of the Arecibo radio telescope, Puerto Rico, a message was sent from Earth in the direction of the globular cluster M13 (Messier 13) situated in the Hercules Constellation some 25,000 light years away from our own location.
In 1979, the University of California, Berkley, launched its own SETI program, the Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations, SERENDIP. Since then, the Berkley program has continued with 3 updates to SERENDIP.
Right from the start of SETI, a major problem faced by investigators was the limited numbers of channels that could be scanned by old style analogue analysers. In 1981, a 131,000 channel analyser, the Suitcase SETI, was built, following the proposals of the Harvard physicist, Paul Horowitz. This state of art instrument was used in conjunction with the 26 metre Harvard/Smithsonian Institute radio telescope at Harvard in a project called Sentinel. But in this business, state of art so often becomes outdated; 131,000 channels were soon not enough. A new system, the Mega-channel ExtraTerrestrial Assay, META, with 8.4 million channels was installed in 1985, alongside a sister module installed in Argentina to scan the southern skies. In 1995, the Billion-channel Extra Terrestrial Assay, BETA, with a quarter billion channels was installed. Unfortunately, heavy winds seriously damaged the Harvard radio telescope in 1999 and put BETA out of commission. The southern META, in Argentina, is still operative after an upgrade in 1996.
In 1992, NASA came back into the SETI with its Microwave Observing Program, MOP. MOP was intended to be a long term project carefully scanning some 800 or so nearby stars as well as carrying out a general survey of the sky. Unfortunately, opposition in the US Congress condemned it to being one of the shortest lived SETI ventures; in 1993, Congress stopped the funding for the program. Thankfully, legislative opposition was insufficient to kill a good idea. In 1995, the non-profit SETI Institute, with private funding, resuscitated the survey of nearby stars under the name Project Phoenix, while the SETI League, Inc, a membership supported non-profit organisation, took up the sky survey under the name Project Argus.
In 1999, the University of California, Berkeley, launched SETI@home, a program that allows ordinary people to link their computers to SERENDIP4 and assist in the ongoing search for extraterrestrial intelligence. Over 5 million computers in more than 200 countries have joined up with this program and have contributed some 20 billion computer processing hours over the period. In terms of processing power, SETI@home is equivalent to the 2nd most powerful supercomputer in the world. THANKS GUYS!
Currently, the SETI Institute and the University of California, Berkeley, are working together on the Allen Telescope Array, named for Paul Allen, co-founder of Microsoft and a major benefactor of the project, a specialised array for SETI investigations.