Posted by In September 1959 two physicists at Cornell, Giuseppe Cocconi and Philip Morrison, published a two-page paper in Nature with a modest title, Searching for Interstellar Communications. They pointed out that radio telescopes of the day could already detect a transmitter of reasonable power at the distance of the nearest stars, and they suggested where on the dial to listen: near the 1,420 megahertz line emitted by cold hydrogen, a frequency any astronomer anywhere would know. The paper ends with a line still quoted at conferences. The probability of success is difficult to estimate, they wrote, but if we never search, the chance of success is zero. Modern alien research, as a scientific activity with budgets and peer review, starts roughly there.
What followed over the next six decades was less a straight line than a series of bold experiments, false alarms, funding fights and slow lessons about what counts as evidence. That history explains why the field looks the way it does today.
An 85-Foot Dish and Two Nearby Stars
Frank Drake had independently reached the same idea, and in the spring of 1960 he turned the 85-foot radio dish at Green Bank, West Virginia, toward two Sun-like stars a little over ten light-years away, Tau Ceti and Epsilon Eridani. He called it Project Ozma, after the princess in the Oz books. Over a few months he listened near the hydrogen line with a receiver that, by modern standards, scanned a ridiculously narrow slice of spectrum.
He heard nothing from either star. Ozma mattered anyway, because it showed that the search could be framed as an observation with a defined target, frequency and sensitivity. A null result became a measurement, an upper limit on what was there, rather than a disappointment. That shift in attitude is still the backbone of the subject.
The same year, Freeman Dyson published a short paper in Science arguing that a sufficiently advanced civilisation might capture most of its star’s energy and glow in the infrared as a result. Nobody had to send a message for that idea to work. It quietly widened the search from listening to looking.
Seventy-Two Seconds in Ohio
On 15 August 1977 the Big Ear radio telescope at Ohio State University swept across a patch of sky in Sagittarius and recorded a narrowband signal that rose and fell over about 72 seconds, exactly the profile expected from a fixed point in the sky drifting through the telescope’s beam as Earth turned. A few days later the volunteer astronomer Jerry Ehman, going through the computer printouts, circled the characters 6EQUJ5 and wrote Wow! in the margin.
The signal never came back. Big Ear had two feed horns, so a source in the sky should have been seen twice in quick succession, and it was recorded only once. Later searches of the same region, with far more sensitive instruments, found nothing. Natural explanations have been proposed over the years, none universally accepted, and the event remains what it was on the night it happened: a single unrepeated detection. It is the most famous result in the history of SETI, and in a sense it taught the most important lesson. Without a repeat, nothing can be confirmed.
The Viking Puzzle
The biological side of alien research had its own formative episode a year earlier. In 1976 NASA’s two Viking landers put three life-detection experiments on the Martian surface. One of them, Gilbert Levin’s Labeled Release experiment, dripped a nutrient solution containing radioactive carbon onto soil and watched for radioactive gas. Gas came out, much as it would from living soil on Earth.
Another instrument, a gas chromatograph-mass spectrometer, found no organic molecules at detectable levels. Without organics, most scientists argued, the Labeled Release result had to be chemistry, some reactive compound in the soil, not metabolism. Levin argued for the rest of his life that the result had been biological. The puzzle partly eased in 2008 when the Phoenix lander found perchlorate in Martian soil, a reactive salt that can produce such effects and that may also have destroyed organics during Viking’s heating. Curiosity later did find organic molecules preserved in ancient mudstone in Gale crater, reported in 2018. None of this proves Viking saw life. It does show how an experiment designed to give a yes-or-no answer can produce neither.
Planetary scientists took the hint. Since Viking, missions have generally focused on habitability, on reading the environmental history of a world, before trying to detect life itself.
Money, Politics and a Few Million Home Computers
For a short time the search had official backing on a large scale. NASA’s High Resolution Microwave Survey began on 12 October 1992, the five-hundredth anniversary of Columbus reaching the Americas, with plans to monitor millions of radio channels at once. About a year later Congress cut the funding, with Senator Richard Bryan of Nevada leading the opposition, and the program was cancelled. The word SETI became something close to unmentionable in NASA proposals for years.
The work survived largely on private money. The SETI Institute, founded in California in 1984, carried on with donated funds. At the University of California, Berkeley, the SETI@home project, launched in 1999, handed out slices of radio telescope data to volunteers whose idle home computers chewed through them as a screensaver; millions of people took part before the project stopped sending out new work in 2020. It found no aliens. It did help popularise the idea of distributed computing.
The largest private effort arrived in July 2015, when the investor Yuri Milner announced Breakthrough Listen, a ten-year program backed by 100 million dollars that bought large amounts of time on major radio telescopes and on an optical telescope. A few years later NASA itself returned to the subject cautiously, hosting a workshop on technosignatures in Houston in 2018. Under the new vocabulary the old ideas had become respectable again.
Strange Stars and a Visitor
The more recent history of alien research is a history of anomalies that got serious attention and then ordinary explanations. In 2015 volunteers on the Planet Hunters project noticed that a star in the Kepler field, KIC 8462852, sometimes dimmed by much more than any planet could cause, in irregular, lopsided dips. The astronomer Tabetha Boyajian led the paper describing it, and for a while the press discussed giant alien structures around what was soon nicknamed Tabby’s Star. Follow-up observations showed the dimming was deeper in blue light than in red, which fits dust and does not fit a solid opaque structure. The star remains odd, though nobody serious attributes it to engineers.
In October 2017 the Pan-STARRS survey in Hawaii spotted ‘Oumuamua, the first known object to pass through the Solar System from interstellar space. It was elongated or flattened, tumbling, and accelerated slightly as it left in a way gravity alone did not explain. Avi Loeb of Harvard suggested it might be an artificial light sail. Most researchers prefer natural explanations involving gas escaping from an icy body, though without a coma to observe, the details are still argued over.
Both episodes ended the same way. Interesting object, careful follow-up, natural explanation favoured. That is not a failure of the field. It is the field working.
A Scale for Saying Maybe
The newest development is cultural rather than technical. Astrobiologists have noticed that announcements tend to arrive as headlines with no indication of how strong the evidence is. In 2021 a group led by NASA chief scientist James Green proposed a Confidence of Life Detection scale in Nature, with seven steps running from detecting a signal that might be biological, through ruling out contamination and non-biological sources, up to independent confirmation by follow-up observations. The idea is simple: say how far up the ladder a claim has climbed, and the public can tell a first hint from a finished case.
Seen in that light, the whole story since Cocconi and Morrison is about building the lower rungs. Better receivers, cleaner samples, more patient statistics, and a strong collective memory of Wow!, Viking and Tabby’s Star. If you like your alien research with the history and the caveats left in, SETIworld keeps telling that story as new candidates come and go, and there is plenty more of it waiting on the portal.
