Has NASA detected alien radio signals in the three months since it launched history's most comprehensive (and most touted) search for extraterrestrial intelligence?
Actually, no."We hardly expected anything to show up right at the very beginning," said John Billingham, chief of the search. Billingham, based at NASA's Ames Research Center, Mountain View, Calif., was interviewed by telephone.
On Oct. 12, the 500th anniversary of Columbus' discovery of the New World, NASA switched on a computerized search for signals from other-worldly civilizations. Using immense radio telescopes and sophisticated scanning software, the project is expected to take five years to complete. It is supposed to cover thousands of radio frequencies at great sensitivity.
In addition to general sky scans, a high-sensitivity targeted search was to focus on stars like our sun in our "neighborhood" - within 80 light-years of Earth.
So how has it gone so far? "We did some intensive searching of, I think it was, 25 neighboring stars . . . with very high sensitivity over a six-week period," Billingham said. Experts at the Jet Propulsion Laboratory, Pasadena, examined the signals received with their special computer program.
"And the answer is no," he said.
"We detected a lot of `hits,' a lot of signals, but they all turned out to be of terrestrial origin. There were various transmitters."
Among the false blips were signals from radars, sounding balloons and other transmitters that happened to move in front of the radio dish.
Sometimes, he said, "the signal is so strong that it comes over the edge of the dish." For example, the San Juan, Puerto Rico airport - 50 to 75 miles from the 1,000-foot dish at Arecibo - was strong enough to leak signals that the dish picked up.
These immediately showed up as "very suspicious," as they were on the frequency of the airport radar. "It didn't take long to confirm," he said.
One test to help determine whether signals originate on impossibly remote planets is whether they remain fixed in the sky. If the source seems to rotate overhead, the same way the sun "moves" as the earth turns, that indicates it comes from a remote source.
"All the signals that we got are not fixed in the sky," Billingham said.
NASA's cosmic fishermen have used their targeted search with the first 25 holes, without even a tentative nibble. But the program will continue. In the next 10 years, the targeted search should probe 1,000 stars.
Meanwhile, the targeted search is in a hiatus.
"The targeted search system in its tractor trailer rig is now back here at Ames being upgraded and improved," he said. Soon it'll be sent to another radio telescope, a smaller one - probably the 140-foot dish at Green Bank, W.V.
The West Virginia radio telescope is less powerful than the monster at Arecibo. "But this is the telescope which is going to become our permanent northern hemisphere site in 1996, so we're anxious to get some experience on it," he said.
Billingham isn't discouraged about the lack of radio contact so far. "Of course we don't know how long or how tough a task (it will be to discover transmissions from another civilization) . . . We could detect a signal in a year or two, or it could be eight or nine years.
"We just don't know. It may be that we don't detect a signal and have to go onto the next stage with a technologically much more advanced and sophisticated signal than we now have."
Meanwhile, the all-sky survey is continuing with the radio telescopes of the NASA Deep-Space Communications Network, located in the Mojave Desert near Goldstone, Calif.
And hope springs eternal. "Please call me back at six-month intervals," he advised.