Are there aliens out there? Based on statistics alone, the answer should be a resounding yes. The Milky Way has at least 100 billion stars and the vast majority of these have planets orbiting them. But while the numbers are on our side, evidence remains lacking.
The Breakthrough Listen project has delivered the first results of its massive new SETI (search for extraterrestrial intelligence) survey in search of alien civilizations. And when we say massive, we mean massive. The observations looked at 60 million stars towards the galactic center, a region where stars are more tightly packed. By looking at quite a small but busy portion of the sky, astronomers can study lots of worlds.
The team collected 600 hours of data using the Green Bank Radio Telescope in West Virginia and CSIRO’s Parkes Radio Telescope in Australia, detailing the observations in a paper accepted for publication in The Astronomical Journal.
The team did not find any signals, but it's important to note that they were looking at purposely emitted signals, known as technosignatures – optical or microwave signals, laser emissions, even "megastructures" – in this search; some sort of alien beacon that says “Hey, we are here!” or given the distances involved, “Hey, we were here thousands of years ago!”
A search for a radio emission that has not been sent out on purpose requires a lot more work. The team uses the expression “eavesdropping on the leakage radiation.” While science fiction often focuses on the potential for TV transmissions to be the primary signal, from Earth the biggest leakage is actually from airport radar. So perhaps future searches will spot these kinds of signals rather than a transmission of Real Housewives of Zeta Reticuli Prime.
While the survey didn’t find aliens, it does push the envelope on what it can be achieved when it comes to the search for extraterrestrial intelligence. “We compared the sensitivity of our survey to some of the prominent SETI surveys and demonstrate that our survey has remarkable sensitivity with a frequency span never before explored for SETI,” the authors conclude in their paper.
There is no one way to look for alien life but searching for technosignatures is one in which humanity has placed a lot of hope for discovery as these signals might be easier to spot than discovering particular molecules in the atmosphere of distant planets, known as biosignatures.
Alien life may even be found in simple structures closer to home; in the deep oceans of the moons of Jupiter and Saturn, or maybe even on Mars.