In an effort to detect the radio emissions from a hypothetical extraterrestrial intelligence, it helps to know where to look. Space, after all, is a very big place and the chances of accidentally stumbling across an alien television signal is very low.
So, using data from the Kepler space telescope, astronomers are becoming more focused on "listening" for radio signals coming from stars known (or at least thought) to have planets orbiting them. And it seems the first "candidate" signals have been detected!
But before you start popping the "we've discovered ET!" champagne corks, this first signal is most likely terrestrial in origin.
"We've started searching our Kepler SETI observations and our analyses have generated some of our first candidate signals," scientists of the University of California, Berkeley announced on Friday.
Sadly, the first candidate signals aren't lucky detections of alien radio transmissions, they're "undoubtedly examples of terrestrial radio frequency interference (RFI)."
Although it's interference from a source here on Earth, the detection of any artificial signal provides the UC Berkeley team with a great opportunity to understand the kind of artificial (alien) signals they hope to eventually discover.
From the UC Berkeley website:
"These signals look similar to what we think might be produced from an extraterrestrial technology. They are narrow in frequency, much narrower than would be produced by any known astrophysical phenomena, and they drift in frequency with time, as we would expect because of the Doppler effect imposed by the relative motion of the transmitter and the receiving radio telescope."
NASA's Kepler space telescope is currently looking for exoplanets orbiting other stars. It does so by constantly looking at the same patch of sky, waiting for these alien worlds to pass in front of their parent stars. When an exoplanet does that - an event known as a "transit" - the starlight dims slightly, and Kepler registers a "candidate" exoplanet.
For the world to be confirmed, it needs to complete four transits. As one of Kepler's prime mission objectives is to discover Earth-sized exoplanets orbiting within the habitable zone of sun-like stars, we have to wait 3.5 years until Kepler can confirm their existence.
As explained in the Discovery News article "Big Question for 2012: Will We Find Earth 2.0?," we may start to glimpse hints of the first true "Earth-like" worlds orbiting other stars by the end of 2012.
So the logic is that if SETI directs their radio telescopes at star systems known to contain exoplanets - preferably exoplanets with similar qualities to Earth - then perhaps life evolved in a similar way as it did on Earth. If this extraterrestrial life is going through the "radio transmitting" phase as we are currently, then perhaps we might detect them on one of these exoplanets.
Although the likelihood of discovering ET is still very low, at least Kepler is giving the search for intelligent aliens a better chance.
Image: The radio signal detected by the 100-meter Green Bank Telescope in West Virginia while scanning the exoplanetary candidate KOI 817. This is the kind of signal SETI scientists would expect to find if an alien civilization is transmitting. Source: UC Berkeley/SETI