The search for extraterrestrial intelligence: A “neglected” quest no longer?
Discoveries of new habitable worlds have spurred hope among scientists searching for alien “technosignatures.”
“I’m an observer,” said astronomer Jason Wright. “I’ve always enjoyed the little corners that are being neglected.” In recent years Wright has been exploring one such neglected corner—the search for extraterrestrial intelligence, or SETI. He is optimistic that it will soon be full of activity.
Wright, associate professor of astronomy and astrophysics at Penn State University, expressed this hope to science writers visiting State College, Pa., for the ScienceWriters2019 conference. Speaking as part of the New Horizons in Science briefing organized by the Council for the Advancement of Science Writing on Oct. 28, he shared a vision for SETI’s future.
That future, Wright pointed out, hasn’t always looked promising. The official SETI program at the National Aeronautics and Space Administration (NASA) was frequently a target of congressional ridicule and was terminated in 1993. Since then, other branches of SETI have suffered and dwindled owing to a lack of federal grant funding. SETI research has survived thanks to philanthropic donations.
The four-letter word
Today, SETI is no longer the four-letter “S” word at NASA. Wright noted that numerous exoplanets have been found—many of them within “habitable zones”—and Earth-sized planets are common among them. A habitable zone is the region around a star in which an Earth-like planet can possess liquid water on its surface and possibly support life.
Furthermore, people care about whether we are alone in the universe. “Everyone gets SETI,” Wright said. “You say, ‘I’m looking for technological life in the universe,’ and they get the importance immediately, and a lot of that has to do with science fiction…it’s the height of pop culture.”
Wright, who is affiliated with Penn State’s Center for Exoplanets and Habitable Worlds, searches for “technosignatures,” evidence of technology not created by Earth’s residents. Technological life is “any life that engineers something I can detect as an astronomer,” explained Wright. “Maybe they engineer a radio transmitter, and I can detect that with a radio telescope. Or maybe they engineer enormous structures in space, and I can detect those blocking the starlight.” Wright hopes that changes in attitude toward SETI will lead to the federal grant funding necessary to continue this search.
Looking for technological life
One might imagine that the sheer size of space would preclude the possibility of finding extraterrestrial intelligence or technosignatures such as radio transmissions. But Wright isn’t worried about this. The universe is very old, and the possibility of a technologically advanced society exists.
“If we had an outpost on Alpha Centauri,” he said, “we could communicate with it by radio. That’s within our technology, but the ping time is [approximately] 8 years. So you’re not having a conversation; you’re sending and receiving information. It’s so asynchronous that it’s not a real interaction, but at least it’s within your lifetime.”
Sending a physical probe like Voyager is another way to communicate but takes a much longer time. “Physical contact is both easier and harder,” Wright said. “It’s easier in that it doesn’t actually take that much energy to send a probe across the galaxy. Voyager is going to cross the galaxy. The hard part there is not energy, it’s time.”
“It would take Voyager something like a billion years to cross the galaxy, and there’s a lot of stars along the way,” Wright explained. “If technological, space-faring life arose 5 billion years ago, which is a very reasonable hypothesis, they have been doing whatever they have been doing for billions of years.”
Essentially, space may be really big, but there has been enough time that if a species had started producing technosignatures billions of years ago, then contact with those civilizations is not out of the question.
Funding the search
Back in the present, the funding needed for such extraordinary discoveries is still lacking. “We’re not even writing proposals; we’re asking for permission to write proposals,” said Wright. Fortunately for Wright and his colleagues, NASA now will accept their funding requests. But will the proposals eventually lead to federal grants? Wright said a lot of his hopes lie in the Decadal Survey on Astronomy and Astrophysics (Astro2020).
Astro2020 is a survey done by the National Academy of Sciences, which is collecting broad input from the astronomy community in order advise Congress on what projects should get priority. Much astronomy advances through very large, multi-decade projects such as the Hubble Telescope or the James Webb Space Telescope, and so astronomers need a vision that isn’t going to change. But if the final report from Astro2020 says that NASA should be funding SETI, Wright believes Congress will most likely endorse it. That is the first step in securing the future of SETI.
Brighter than a brown dwarf: the future of SETI
The tools for SETI searches are improving at institutions such as Penn State, which has become a hub of “multi-messenger” astronomy. In the past, astronomers primarily relied on light to explore the universe. But, according to Wright, scientists now gather information about the universe from three other “carriers:” the particles called neutrinos, cosmic rays, and gravitational waves. Instruments can detect all of these carriers as they bring information from sources beyond the solar system.
What would happen if astronomers did detect technological life using multi-messenger astronomy? Wright explained that it depends on how far away the signal’s source is. “When we are looking for these signatures, generally we are focusing on nearby stars. If they are in one place, they are probably in lots of places,” he said. “We don’t expect to see a species that is only recently technological, because the chances that you’d happen to see that little flash [of technology] are very low. So, especially since you’d only really see the long-lived ones, the chances that they’d go extinct a thousand years since they transmitted seems very low to me.”
Wright’s first SETI project, funded by the Templeton Foundation, was a high-risk proposal to look for Dyson spheres, alien megastructures that encompass a star. This project was inspired by the technology that discovered star-like objects called Y brown dwarfs. These are cold—very cold—and, thus not very bright. However, the future of SETI is much brighter, particularly for Wright. “I have a lot of things I want to try. I want to spend my time searching,” he said. In his little corner of this neglected field of astronomy, Wright continues to search and observe.