Growing up in New York City, 8-year-old Jill Tarter had never experienced dark like it. She was in Florida. She had traveled to the Sunshine State only to experience a true absence of light, but the sky wasn’t dark at all. It was filled with bright, shining stars. As she walked along the beach with her father, the specks of flickering illumination feeding her imagination, Tarter experienced an insight that would define the rest of her life.
Gazing upward, she asked herself: What if, revolving around one of those stars, was a planet much like Earth? And what if, on that planet there was a beach where a young creature walked with her father, watching the stars from her own galactic neighborhood? And what if, as this creature gazed and wondered, she glimpsed the light of a distant star around which a small planet revolved on which there was a beach where Tarter walked with her father, looking up and wondered: What if we’re not alone?
“That became my worldview; that was just my mindset for as long as I can remember,” Tarter reflected.
An AAAS Fellow since 2002, Tarter has spent the majority of her career in astronomy transmuting the wonder she felt on that beach into a systematic search for intelligent life elsewhere in our galaxy as head of the research arm of the Search for Extraterrestrial Intelligence Institute, better known as the SETI Institute.
Beloved by many and disliked by others, the SETI Institute has for decades aimed radio telescopes at the sky in an effort to tease out potential signals of extraterrestrial origin from the cosmic noise of space. What became the SETI Institute began as independent scientific searches, eventually falling under a series of NASA programs until, in the mid-1990s, U.S. lawmakers cut the programs’ funding.
However, the search endured. Tarter and other researchers associated with NASA’s SETI work created the nonprofit SETI Institute a decade earlier as a way to continue their search if public funding dissolved. When it did, Tarter and the Institute turned to private donations, mostly from Silicon Valley luminaries, such as Bill Hewlett and David Packard of Hewlett-Packard. During this time, Tarter became the most recognizable face of SETI, pitching the project’s science and philosophy to private philanthropists while honing SETI’s search techniques through overseeing the construction of new hardware and new computer algorithms. Her tenacity even earned her a place in pop culture history, when in 1981, her friend and colleague Carl Sagan based the protagonist of his science fiction novel Contact on her. The book was later made into a movie in 1997 staring Jodie Foster.
“When Carl sent me a pre-publication copy of the book, I was flummoxed. There was so much in that character that was in common with my life,” said Tarter.
A look at Tarter’s career shows the accolade from the iconoclastic Sagan was well-deserved.
While her childhood experience on that Florida beach stuck with her into early adulthood, Tarter nonetheless began her career in science with an aspiration that was a little closer to home: “I wanted to go to the moon,” said Tarter.
However, in the early 1960s, when she started her undergraduate program in engineering, science and engineering, let alone becoming an astronaut, were culturally off-limits for most women. So much so that Tarter found herself in the awkward position of being the only woman in a class of some 300 students. Nonetheless she excelled, and soon she began to stretch beyond engineering to astronomy, eventually earning her Ph.D. in the subject. It was around this time that she first waded into scientific controversy.
In the mid-1970s, it was believed that there existed approximately 10 percent more mass in the Milky Way than could be accounted for by observations. Tarter proposed that some of this missing mass was due to a type of star that hadn’t yet been found. She believed these stars would not be massive enough to fuse hydrogen into helium, as our sun does. This meant they would be cool and, for all practical purposes, invisible to our instruments. She called these strange stars Brown Dwarfs.
When she first proposed Brown Dwarfs, Tarter had a hard time convincing scientific publications that these small, cool stars existed. Meanwhile, the amount of missing mass grew in calculations, eventually being pinned largely on mysterious dark matter. Nonetheless, the idea of Brown Dwarfs caught on, and the first of what would be many Brown Dwarfs was discovered in the mid-1990s. Tarter was vindicated.
“That was a lot of fun. That was a very enjoyable time,” said Tarter of the discovery.
Tarter has yet to be vindicated in her search for extraterrestrial intelligence, but she hasn’t given up hope. Since SETI investigations began in the 1960s, only a miniscule portion of the night sky has been surveyed—the equivalent, by Tarter’s calculations, of taking a single glass of water from the world’s oceans. What’s more, as Tarter knows, searching for signals in space is complicated. Space as viewed through a radio telescope is a noisy place. Then there’s the fact that information-laden signals tend to look like noise at first glance. Add to this the multiple frequencies that could be used for broadcasting, the fact that all the sources of broadcast are in constant motion, and, most important, time—the time it takes for complex life to evolve, technological civilizations to develop, and the cosmic speed limit that is the speed of light—and you find yourself with a complex engineering problem.
“After millennia of asking priests and philosophers what we should believe, suddenly we engineers and scientists have tools, telescopes and computers, to actually figure out what is,” said Tarter.
Tarter’s first opportunity to apply her skills to the search for extraterrestrial intelligence came in the late 1970s. A colleague of hers wanted to do a search by piggybacking on a radio telescope, and he needed a computer programmer. Tarter just happened to be one of the few people who could program the computer he was using. The researchers’ plan was simple: Take recordings from the radio telescope using magnetic tape, then search the recordings using a computer algorithm programmed by Tarter. This is essentially how SETI still works.
“Only we’ve now gone from 100 channels to 100 million channels. That’s been the progress that computing power has allowed us to achieve,” said Tarter.
SETI, like other data-heavy endeavors, has benefited from the recent explosion in computing. This has allowed SETI to search for more complex and seemingly noisier signals. SETI’s hardware has also significantly improved, most notably on projects like the Allen Telescope Array, named after funder and Microsoft co-founder Paul Allen.
Still, Tarter is realistic. Even with the best hardware and software there could be a lot of searching before we get pinged with a message from the stars, if one shows up at all. That’s because for two civilizations to talk they not only need to be close enough in space to discover one another but also close enough in the long history of our galaxy to overlap. But if they do overlap, that raises the possibility that technological civilizations might be sustainable in cosmic time, raising the further possibility that young civilization like ours could one day overcome the ecological and social upheavals our technologies have produced. This, says Tarter, as much as answering the question she first asked walking along that Florida beach is what should feed our collective imaginations.
“If technologies pop up around the universe frequently, but in very short time they do themselves in or turn themselves off, then you are never going to get two technological civilizations that are coeval. But, if we know someone else has succeeded, that could be the motivation we need to help us find the solution to the problems that we’re facing,” said Tarter.