Searchers for extraterrestrial intelligence have spent years listening for continuous, structured signals being punched through interstellar space by a civilization lavishly investing energy and technology in an attempt to contact its neighbors.
But what if the alien scientists running this project were on a budget — just like their human counterparts? They’d have to take a more economical approach.
That’s why future researchers will probably be looking for “Benford beacons.”
Astrophysicist and SF writer Greg Benford, his brother Jim — a physicist specializing in high-powered microwave technology — and Jim’s son Dominic, a NASA scientist, contributed two studies to the June issue of Astrobiology . They propose that an alien civilization striving to optimize costs and make its signaling technology more efficient, would prefer signals that are pulsed, narrowly directed and broadband in the 1-to-10-gigahertz range.
“Omnidirectional beacons are big-time and expensive, but easily noticed,”says James Benford. “But we haven’t seen any, so the observational test result is that they don’t exist.”
“Which is a problem for SETI,” writes Astronomy Now contributor Keith Cooper, because —
many of our detectors are designed to spot exactly these kinds of signals, rather than the shorter beacons. The characteristics of Benford Beacons are a short duration and a rapid revisit time. All they have to do is pique our curiosity and, once detected, we may study the location of the beacon with more scrutiny to try and detect the real message content in the form of a fainter, lower power signal. So we’re searching for what may appear at first glance to be transient radio pulses, and we’ve found plenty of these.
Cooper speculates, “Maybe when we finally open our ears to Benford Beacons, we’ll be surprised to find that everybody has been yelling at us all along.”
[Thanks to Dan Goodman for the story.]