Amateur Participation

Like other areas of astronomy, SETI can benefit from the efforts of amateurs — and not just by using their idle computer time. A powerful beacon elsewhere in the galaxy could easily fall into the enormous coverage gaps of the major SETI programs, yet be detectable with nothing more than a properly equipped home satellite dish and narrowband signal analyzer. These small dishes have a much wider beam that can cover more sky for a longer time than large radio telescopes. Amateurs thus can increase the breadth of coverage, though at the expense of much less depth (lower sensitivity and noise rejection).

Examples of small-scale SETI efforts include Project BAMBI ("Bob And Mikes' Big Investment"), a pair of small, 3.1-million-channel radio telescopes intended to observe in parallel from California and Colorado 1,000 miles apart to screen out local interference. Bob Lash, Mike Fremont, and Mike Fox designed their setup to explore frequencies near 4 GHz, higher than other searches. "To up the odds a bit," writes Mike Fox, "we have decided to point our dishes straight down our spiral arm [of the Milky Way]. This gives us the maximum number of stars in each patch of the sky we are looking at."

As of August 2003 both BAMBI stations were being upgraded to 12-foot (4-meter) dishes, according to Bob Lash. He also said the team may use the BOINC distributed-computing spinoff of SETI@home to recruit volunteer data processors; "We might call the project 'bambi@home.' "

Another example is Robert Gray's Small SETI Radio Telescope, which carried out various projects starting in 1983. Gray was also granted time on the Very Large Array radio telescope in New Mexico — quite an accomplishment for an amateur — to follow up on the famous "Wow signal" recorded in 1977 at Ohio State University's Big Ear. (No trace of a signal from the "Wow" location showed up even with the VLA's vastly greater sensitivity.) More recently Gray monitored the Wow site for extended lengths of time using a 26-meter dish in Tasmania.

Starting in 1995 the SETI League, directed by H. Paul Shuch in Little Ferry, New Jersey, made ambitious plans to coordinate amateur stations worldwide through its Project Argus (not to be confused with Ohio State University's next-generation Argus omnidirectional radio telescope). The SETI League's ultimate goal was to have 5,000 small, amateur radio telescopes around the globe monitoring the entire celestial sphere continuously. In many cases, such observing stations have cost their builders only several hundred to several thousand dollars. The SETI League offers technical guidelines and help in getting parts and software.

However, the SETI League never came anywhere near its goal of 5,000 installations. Among the League's 1,476 members as of July 2006, there were 131 Project Argus participants, and that number had barely budged in the last several years. Moreover, donations were down.

"It's time to redefine our objective for Project Argus," Shuch wrote. "Instead of full-sky coverage, perhaps what we should be striving for is the very best science we can do with however many stations we can muster." Among other things, the SETI League has built a beacon that bounces a weak, narrowband signal off the Moon so that SETI workers worldwide have a celestial standard for testing and calibrating their equipment. More recently the League obtained a patent for a new method of combining signals flexibly from small radio telescopes, based on a prototype SETI instrument named the Very Small Array that Shuch and other members have built.

James Brown of Del Mar, California, is a prolific SETI League member who started building amateur SETI gear in 1978. He has written extensive astronomical, coordination, and signal analysis software, which he shares worldwide through his seti.net website. In April 2005 he received the League's Giordano Bruno award for his ongoing work. As of 2011 he was using a 10-foot dish; knowing its limited capabilities, he was using it to monitor the L4 and L5 stable Lagrangian points, just 1 a.u. away in Earth's orbit, for any beacon transmitter that aliens may have parked there long ago.

Amateurs in Australia have been developing several SETI installations through the SETI Research & Community Development Institute. Among other things, members of the group have sought rights to an old but huge, fully steerable, 33.5-meter (110-foot) dish at Carnarvon. SRCDI director Noel C. Welstead wrote (December 2003) that it will take "a few more years of work running through the government red tape to fully secure the use of this impressive antenna. We can't wait."

Meanwhile, he wrote, "We are constructing the Boonah SETI Observatory, where we will be conducting searches in both the optical and radio spectrums. We recently had 'first light' with our 5-meter Argus station," detecting the weak Project Argus signals bounced off the Moon. "Also, construction has commenced on the twin 40-foot [12-meter] dishes that will be our primary ears to tune into the universe. Our optical facility has seen first light with the commissioning of the 14-inch Schmidt-Cassegrain telescope. Work has begun on the optical detectors that will get the optical SETI project up and running."

Strengths: Enough small amateur radio telescopes, running continuously, could watch large swaths of the sky all the time in case alien radio emissions at a well-guessed frequency are strong but intermittent.

Weaknesses: Mostly tiny apertures, tiny bandwidths (though this should improve), labor-intensive signal analysis, unsophisticated false-alarm rejection — and members' unpredictable commitments to very long-term, long-shot projects.

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