A call from outer space, or a cosmic wrong number?
It’s probably just a piece of cosmic spam, the astrophysical equivalent of butt dialing. But nobody really knows for sure.
The attention of the world’s astronomers and a bit of the internet was riveted last week on a star in the constellation Hercules, wondering if the end of humanity’s cosmic loneliness was finally at hand.
It was from that spot in Hercules that a team of Russian radio astronomers recorded a two-second burst of radio waves last year on May 15. But the Russians did not follow the usual protocol of alerting other observatories that could confirm the signal, and as a result nobody else knew about the pulse until the end of August.
That putative signal had the potential to be the fantasied “Hi there,” from another world that practitioners of the field known as SETI, the search for extraterrestrial intelligence, have been looking for over the last century. Or it could simply be a false alarm from terrestrial interference, a stray military transmission or some rare astrophysical misunderstanding.
Astronomers already knew there was at least one planet, about 17 times the mass of Earth, circling that star, which is 94 light years from here and goes by the unheroic designation of HD164595.
But there were also problems, the Russians, led by Alexander Panov of Lomonosov Moscow State University, realized. The signal appeared only once in 39 observations, and to produce the observed signal at such a distance would take a transmitter with the power of at least a trillion watts, comparable to the total energy consumption of all humankind.
Moreover, the design of the Russian telescope, known as Ratan-600, a giant circle of antennas in the Caucasus near Georgia, leaves it susceptible, astronomers say, to radiation from unwanted directions, increasing the chances of interference from military or other terrestrial sources.
Word finally got out when Claudio Maccone, chairman of the SETI committee of the International Academy of Astronautics, circulated a description of the observations in advance of a SETI meeting to be held Sept. 27 in Guadalajara, Mexico. While the report did not claim that this was an alien detection, it did say, “Permanent monitoring of this target is needed.”
In an email on Aug. 29, Maccone, a member of the team, said he agreed with his colleagues. “I certainly share the view that it is likely not an intelligent signal,” he said. “Nevertheless it had to be PUBLISHED, rather than being kept secret for over a year, and this is what I did: convince the Russians to publish it.”
After astronomy writer Paul Gilster reported it on his blog Centauri Dreams, the signal went supernova on the internet.
But so far the results have been zilch. Starting on the night of Aug. 28, astronomers from the SETI Institute of Mountain View, California, swung into action with the Allen Telescope Array, a set of antennas in Hat Creek, California, built specifically to look for alien broadcasts.
After two nights of observing, Seth Shostak, spokesman for the institute reported, “We covered the frequencies observed by the Russians and more ... No dice.”
Meanwhile astronomers from Breakthrough Listen, a new SETI project funded by the Russian philanthropist and entrepreneur Yuri Milner, used the Green Bank Telescope, in Green Bank, West Virginia, the world’s largest steerable radio dish, to check out the star. They found nothing but noise.
Indeed, according to Tass, the Russian news agency, the researchers had also concluded that their signal was a result of terrestrial interference. The observatory, the researcher Yulia Sotnikova said, was preparing an official disclaimer of any media claims of extraterrestrial contact.
Everybody plans to keep looking, but for now the Hercules signal seems destined to join the other false alarms that have characterized the SETI endeavor, most notably the “wow” signal that appeared on the printout of an Ohio State radio telescope in 1977 but never reappeared.
As Maccone said in the email: “There were similar cases in the past, and probably there will be more in the future. The point is to PUBLISH everything and EXCHANGE DATA worldwide about the stars where they come from.”