There's still no sign of alien life, but that hasn't stopped researchers from looking for the past 50 years.
In 1960, renowned astronomer Frank Drake spent 150 hours holed up in the Green Bank Observatory, using a giant radio telescope to look for aliens. The experiment, known as Project Ozma, focused on two nearby stars—Tau Ceti and Epsilon Eridani—which Drake had selected for observation. But at the end of the project, he had little to show for his efforts: He hadn't found any signs of intelligent life.
Though he didn't know it at the time, Drake's experiment had paved the way for the modern search for extraterrestrial intelligence, or SETI, in shorthand. Drake's pioneering use of radio waves would change the way scientists scanned the cosmos for signs of life, meaning his expensive and embarrassing failure had actually revolutionized the search for aliens, and would inspire SETI programs at institutions like Harvard, NASA's Jet Propulsion Laboratory, and the SETI Institute in Mountain View, California.
But in 1961, Drake couldn't have known any of this. So he called an informal conference of 12 men—among them, a handful of Nobel laureates and a young Carl Sagan—to come to Green Bank Observatory and decide if it were financially and scientifically justifiable to search for extraterrestrial intelligence. Not only did the group decide that SETI was a worthwhile venture, but they began working on concrete research methods. One of these methods was the Drake equation, a formula meant to quantify the number of extraterrestrial civilizations that could be expected to be found in the Milky Way. Based on his formula, Drake would peg this number at 10,000; Sagan, in his unflagging optimism, estimated it was closer to a million.
In the years after the Green Bank conference, the search for life beyond Earth remained mostly a fringe enterprise, and SETI was little more than an umbrella term for a loosely-affiliated sect of space scientists prowling the cosmos for extraterrestrial life. But in 1971, NASA became interested in SETI after developing Project Cyclops, which would use 1,000 100-meter telescopes to search for radio signals from neighboring stars.
Project Cyclops was ultimately scrapped—in part due to its astronomical price tag of $10 billion—but it jumpstarted the space agency's interest in SETI research, building on those early experiments from Drake. By 1976, NASA's Ames Research Center and JPL both had their own fledgling SETI programs. Within a decade, a number of independent SETI initiatives had sprung up up, including Sagan's Planetary Society, which funded small JPL and Harvard SETI initiatives; the "Serendip" program at the University of California, Berkeley; the University of Ohio's "Big Ear" program; a number of initiatives in the Soviet Union; and of course, the SETI Institute, which was founded in 1984.
Still, not everyone thought scientists should spend time—and precious research money—staring into the sky to look for aliens. In 1978, US Senator William Proxmire called NASA's SETI program a waste of taxpayer money and succeeded in killing the program's budget in 1981. (He agreed to reinstate the funding in 1983, after a chat with Sagan). When NASA started building hardware for its SETI program in 1988, Congress threw a fit over who was going to pay for it, and defunded the program the following year.
In 1993, after NASA had secured $11.5 million for its newly-minted High Resolution Microwave Survey, US Senator Richard Bryan submitted a last-minute amendment to kill the program once and for all, noting that "this will hopefully be the end of Martian hunting season at the taxpayer's expense." The Senate ultimately approved Bryan's measure and by the time the dust settled, NASA's SETI program was dead.
"Bryan saw SETI as a target that he could use to show his constituents that he was trying to save them money that he considered being wasted by the government," said Seth Shostak, the senior astronomer and director of the SETI Institute. "SETI was easy for him to attack because there weren't thousands of jobs involved. It was a topic he could easily make fun of."
But while NASA's program was dead, SETI researchers were determined to continue their alien hunting. With the help of investors in Silicon Valley, the SETI Institute—which had been contracting with NASA for a number of years—raised $7.5 million to continue the targeted search that NASA had started the year prior. The renewed search was named Project Phoenix, and it logged 100 observation days at Arecibo, a radio telescope in Puerto Rico, as well as 2,600-plus hours at the Parkes radio telescope in Australia.
"Project Phoenix was rising from the ashes of NASA's SETI program," Shostak told me. "Some of [the SETI Institute's employees] had been at NASA. They joined the Institute when all the SETI employees at NASA had to stop working on SETI. If they joined the Institute, then maybe they could continue on their project—and some of them did that."
Since then, the Institute has been the preeminent source of SETI initiatives, which are funded exclusively through private donations. The organization has overseen over 100 projects since its inception, including building its own SETI-dedicated array of telescopes, known as the Allen Telescope Array. It's the only institution of its kind, but Shostak is cautious about calling it the largest—there are only five people at the Institute who actively search for intelligent life.
"Ninety-six percent of the scientists [at the SETI Institute] are doing investigations into life that is not-so intelligent," said Shostak. "Think bacteria under the sands of Mars, or maybe under the icy skins of Europa. Most of the effort here is actually astrobiology."
According to Shostak, the emphasis on astrobiology is a reflection of the institute's funding problems. While NASA still provides a significant number of grants for research into astrobiology, it hasn't provided funding specifically for the search for intelligent life since the 90s. Last July, Russian billionaire Yuri Milner announced that he would donate $100 million to boost the search for extraterrestrial intelligence, but according to Shostak, it isn't likely to benefit the Institute directly.
Milner has said that a portion of the $100 million will be saved for "active SETI," which involves intentionally sending messages into the cosmos. This type of research is controversial for two reasons: First, some people are wary that the communications might give away Earth's location to a potentially hostile alien race, in effect inviting the destroyers of human civilization to our doorstep. Others object because there's no consensus on just what the messages should say—and only a select few get to decide what is communicated on Earth's behalf.
"There are people out there who think active SETI is dangerous, but I think it is a phony argument," said Shostak. Still, he added, "it's a controversial subject, so at the moment the SETI institute is not doing active SETI."
Despite the fact that the SETI Institute has yet to receive a "hello" from ET and can't actively send out interstellar messages itself, Shostak and his colleagues believe that their efforts will ultimately pay off.
"You have to look at SETI as exploration because that's what it is," Shostak said. "You could say it's a stupid waste of my money when we've got people starving in the streets, [but] that's the nature of all research. It's all driven by curiosity. That sounds frivolous, but it's not. It's very easy to show that societies which don't have that curiosity disappear rather quickly—so the long term benefits are high. You never know what it's going to lead to."
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