BERKELEY, Calif. — Twenty years after the movie “Contact” brought the search for extraterrestrial intelligence, or SETI, to the big screen, it’s dawning on astronomers that the real-world plotline might turn out to be totally different 20 years from now.
So far, SETI has been dominated by radio telescope surveys looking for anomalous patterns that may point to alien transmissions. But SETI’s practitioners are realizing that E.T. may make its presence known in other ways.
Over the next 20 years, or 200 years, SETI may come to stand for sensing extraterrestrial irregularities, ranging from unusual atmospheric chemistry to higher-than-expected thermal emissions. The telltale signs of life beyond our solar system may even be associated with phenomena we haven’t yet come across.
“Two hundred years from now, people are going to look at what we’re doing, and probably laugh and say, ‘Why weren’t they looking for tachyons, or subspace communications,’ or something like that,” Dan Wertheimer, chief scientist for SETI at the University of California at Berkeley, joked during a presentation held at the university in conjunction with the World Conference of Science Journalists in October.
Questions about the potential for life beyond our solar system are much sharper now than they were in 1997, when “Contact” came out, largely because space surveys have established that there could be billions of potentially habitable planets out there.
Less scientifically grounded developments, such as this month’s revelation that the Pentagon funded secret UFO investigations until 2012, have helped sharpen interest as well.
The Berkeley presentation brought together leading SETI researchers — plus one of the leaders in the study of potentially habitable exoplanets, Guillem Anglada-Escudé of Queen Mary University of London.
The first planets beyond our solar system were detected in the mid-1990s, using a technique that looked for faint gravitational wobbles in the motion of stars. It was a big deal back in 2010 when the list of known exoplanets reached 500. Today, the tally of candidate exoplanets is past the 5,000 mark.
Anglada-Escudé said the planet search is increasingly focusing in on potentially habitable worlds — such as Proxima Centauri b, the nearest exoplanet, which he and his Pale Red Dot team detected just last year.
“The detection has taken so long not because we didn’t have the technology, but because we didn’t know where to search,” he said.
Now that astronomers know how to check red dwarf stars for potentially habitable, close-in planets, “this is going to be happening more often,” Anglada-Escudé said.
Which raises an issue: So far, astronomers have judged the livability of alien planets on the basis of their orbital positions, assumed densities and how much light they get from their parent stars. But to determine whether they’re truly habitable, and whether they have a chance of harboring life, much more information is needed.
Fortunately, more information is on the way — from giant observatories such as NASA’s James Webb Space Telescope, which is now due for launch in 2019; and from smaller, more focused missions such as the Transiting Exoplanet Survey Satellite, to be launched next year.
Such telescopes could tease out the spectral signatures of alien atmospheres, looking for chemical imbalances that could hint at biological activity. It’s more complex than just finding, say, oxygen or water vapor.
“There might be CO2, there might be even molecules we don’t expect to be there at all,” Anglada-Escudé said. “We might see emission features. … When you have the ability to detect methane, oxygen, you can find things that you don’t expect at all.”
Seth Shostak, senior astronomer at California’s SETI Institute, said more powerful telescopes could look for the waste heat given off by highly advanced civilizations, or the radioactive waste left behind by the civilizations that didn’t last.
“There have been schemes proposed for looking for dead alien civilizations,” he said.
In addition to better telescopes, alien-hunting scientists are using artificial intelligence to aid their search.
“We’re just starting to learn how to look for, in machine learning, what’s called anomaly detection,” Wertheimer said. “In anomaly detection, you classify things — ‘this is a curved signal, this is a sinusoidal signal, this is a pulsed signal’ — and if it’s not one of those things, it’ll say, ‘Hey, I found something that’s not following all these categories, this is an anomaly.’ It will alert you, and you’ll take a look at it and see if it’s interesting. We are not doing that now, we’re learning how to do that.”
SETI astronomer Jill Tarter, who served as one of the models for the main character in “Contact,” said the search should really go 24/7 in order to make sure no extraterrestrial anomaly is left behind.
“There’s a big hole in our searches … and that is that we’re not at all very sensitive to transients,” she said. If our telescopes happen to be looking someplace else when E.T. sends out a quick message, the opportunity for contact would be lost.
Tarter said the search for E.T. needs more stable funding in order to better the odds. And in the years ahead, it’ll be even more challenging to keep up with the torrents of data that will come from radio dishes and other types of telescopes.
The evidence of life beyond our solar system may well be found by “carefully combing the astronomical data that are collected every day for things that are anomalous, things that are a little different,” Shostak said.
“I find all that interesting,” he said.