Dan Werthimer has spent more than four decades eavesdropping on aliens.
A pioneering researcher in the field of astronomy known as SETI, or the search for extraterrestrial intelligence, Werthimer’s work involves scanning the cosmos with giant, ground-based radio telescopes in search of strange or inexplicable signals that may have come from extraterrestrial civilizations.
If it sounds a bit like looking for a needle in a haystack, that’s because it is.
In recent years, however, the search for extraterrestrial intelligence has become even more complicated. The increasing demand for mobile services and wireless internet has crowded the radio spectrum and created interference that can distort data and add “noise” to scientific results.
“Earth is becoming more and more polluted,” said Werthimer, chief technologist at the Berkeley SETI Research Center. “It’s already impossible to do SETI on some radio bands because they’re so full of TV stations, WiFi and cell phone bands.”
As wireless technologies continue to grow, the problem will only get worse, Werthimer said, potentially threatening one of the key avenues scientists need to look for intelligent life in the universe.
Werthimer recently co-authored a Chinese researcher-led pre-print study that identified a radio signal that several news outlets incorrectly reported had characteristics of an extraterrestrial civilization. Werthimer clarified that the signal actually turned out to be radio interference.
Targeted SETI research began in earnest in the 1980s and was cemented in popular culture with the 1985 novel Contact by Carl Sagan, which was later adapted into a 1997 film starring Jodie Foster.
At its core, SETI research aims to answer the question: are we alone in the universe? In the decades since scientists first listened for extraterrestrial signals, improvements in telescope technology and data processing have aided the search, Werthimer said.
“We used to listen to one channel, and now we listen to 10 billion channels,” he said. “Technology and science are getting better and better.”
However, these technological leaps come with their own challenges. Due to falling launch costs and cheaper materials to build spacecraft, more satellites than ever are being launched into low Earth orbit. Society’s growing reliance on wireless Internet and GPS navigation also means more competition for radio frequencies.
“It’s a valuable spectrum, and people are always wanting more of it for everyday activities,” said Paul Horowitz, professor emeritus of physics and electrical engineering at Harvard University and a prominent SETI researcher. “It just means the radio spectrum is a mess these days.”
Having relatively clear and unobstructed channels to scan the cosmos is invaluable for SETI scientists. Incorrect human intervention not only creates more work for researchers to filter out, but can also present a falsely intriguing signal.
It’s a conundrum that astronomers are all too familiar with, said Andrew Siemion, director of the Berkeley SETI Research Center and the Bernard M. Oliver Chair for SETI Research at the SETI Institute in Mountain View, California.
To avoid distractions, scientists often rely on repeatability, which can mean studying the same target over longer periods of time to compare observations. In other cases, researchers use what is known about man-made disorders to filter their results.
“As we launch all of these satellites, our knowledge of what’s in space is increasing,” said Siemion, who is also principal investigator of Breakthrough Listen, a 10-year, $100 million initiative to find intelligent aliens life, launched in 2015 by Stephen Hawking and Russian billionaire Yuri Milner.
He added that increased situational awareness in space makes it easier to identify satellites and other forms of human intervention.
“It helps us know that we’re not fooling ourselves by looking at a signal from a satellite and thinking it’s from a distant celestial source,” Siemion said.
Advances in machine learning are also making it faster and easier for scientists to filter out interference from their data, said Bruce Betts, principal scientist at The Planetary Society, which has been involved in SETI research since the organization’s inception in 1980.
Betts said these processing improvements should ensure that SETI research can continue for years to come.
“Even if you have more sources of interference, they will still follow certain frequency patterns and certain time patterns,” he said. “Adding hundreds more satellites all creating the same clutter is really annoying, but you can develop systems to remove that.”
As the SETI research area has evolved, other ideas have also emerged on how to avoid interference in the future. For example, Werthimer, Horowitz, and others are studying ways to search for extraterrestrial civilizations in the optical part of the spectrum.
Others have suggested installing a radio telescope on the far side of the moon, where it would be shielded from interference from Earth. Such a project is technically feasible, but associated with significant costs, Horowitz said.
“SETI has struggled with almost zero government support for the past few decades, so no one is going to want to do that in a financially constrained period,” he added.
But despite technical and financial challenges, Betts says interest in SETI research has grown over time. Much of this can be attributed to the tantalizing possibility of finding intelligent life elsewhere in the universe, he said.
“More than most other discoveries, it would reformulate many of our philosophical views of the universe,” he said. “Yes, it’s a needle in a haystack, but if you find that needle, you’ve made one of the most profound discoveries in history.”