Using one-meter class telescopes at Las Cumbres Observatory in Chile, astronomers are targeting the whole disk of the nearby Andromeda Galaxy in what is arguably the most ambitious optical SETI (Search for Extraterrestrial Intelligence) campaign ever undertaken. It’s part of a trillion-planet survey led by the University of California in Santa Barbara.
The survey includes mass targeting of Andromeda, the Milky Way’s nearest grand spiral neighbor, only 2.5 million light years distant, as well as other nearby galaxies and targets within our own galaxy.
“There are about one trillion stars and hence planets in Andromeda,” Philip Lubin, an experimental cosmologist, and professor of physics at the University of California in Santa Barbara, told me. “This survey looks at more than a million times more sources much than typical radio SETI surveys . We can greatly increase the number with larger surveys.”
Lubin hopes that any alien civilization would try to announce their presence via an arrayed, directed energy beam; one that had been operational for long enough to be detected by a civilization like our own.
Lubin and colleagues are admittedly impatient. So, unlike conventional SETI efforts which focus on only a small part of sky or a few stars at the time, this team is assuming that any advanced alien civilization might use high-powered signaling to flag us down. In theory, such aliens might not only calculate how to best target swaths of sky in our galaxy from outside the Milky Way but have signals that would emit a signature, unlike any naturally-occurring emissions. Thus, they would automatically be noticed.
“We are not looking at individual stars; we want a massive survey,” said Lubin. To that end, Andromeda contains about 1 trillion stars and hence about that number of estimated planets, he says.
The team’s search strategy involves survey chunks of some 2 to 3 degrees, convenient for a model wide-field telescope. The idea is that any such signal could be detected within a relatively short time of a few years if that civilization adopts a simple beacon strategy that Lubin calls “intelligent targeting.”
Based on game-theory and photonics developed at the university, it’s a “blind-blind” system in which neither we nor the extraterrestrial civilization are aware of each other but wish to find one another.
Above all, the survey includes extensive photo analysis to hopefully hone-in on such an intelligent signal. During the analysis phase, the photos are knit together to form a mosaic with each image representing a slice of Andromeda equal to about a thirtieth of its diameter, says the university. These images are then compared to more pristine images in which there are no known transient signals from spacecraft or satellites.
Although Lubin hopes the team will be able to build a more sophisticated multi-color detector in the future, the bottom line as of now is that this one survey could be a game-changer for SETI as we know it .
In a single one-degree square image of Andromeda’s core, there are some 100 billion stars. And there are more than 125 galaxies lying within 12 million light-years of Earth; all of which are ripe for surveying.