The Search for Extraterrestrial Intelligence (SETI) began decades ago as an effort to pick up radio signals from distant civilizations. The effort was centered at the Green Bank Observatory in West Virginia and was by today’s standards quite rudimentary.
A much broader search for distant radio signals remains very much at the core of SETI but the effort has also expanded to be an increasingly rigorous search for “technosignatures.”
These include radio signals, laser beams, the presence of chemical pollutants, unusual planetary heating and even the construction of massive structures around distant planets. All could potentially be signs of intelligent beings living and trying to communicate.
Laser SETI is one of the fastest growing branches of this search of technosignatures and a recent paper that will appear in The Astronomical Journal describes an intriguing technosignature collaboration.
It is a joint effort by The Breakthrough Listen effort, a very large and privately-fund search for evolved extraterrestrial life, and the operators of VERITAS, a ground-based gamma-ray instrument operating at the Fred Lawrence Whipple Observatory (FLWO) in southern Arizona.
The paper does not report any unexpected laser pulses. But as a proof of concept it shows that searching for laser pulses from many light years away is both possible and plausible.
“I would describe our current results as a very promising start,” Gregory Foote, a doctoral student at the University of Delaware and a co-author of the paper, said in an email. “The analysis and observation pipeline is built, so now we can scale up both within VERITAS and with any next generation telescopes which show interest in performing such searches.”
Optical SETI is the name of the overall search for optical technosignatures; signals based on optical light emitters such as lasers. There are two types of laser-based signals that astronomers are currently looking for — a continuous laser beam at a specific wavelength, and nanosecond time-scale pulse lasers. The VERITAS telescope can detect the nanosecond burst of lasers.
“Overall, if one wants to build an interstellar communication system, using pulsed lasers is a power-efficient way to do it,” Foote said. “The technology for both transmitting and receiving doesn’t require any sci-fi infrastructure: it exists today.… Read more