Was it a call from ET?

No one believes it was with ET calling, but radio astronomers admit that they do not yet have an explanation for a ray of radio waves that apparently came from the direction of the star Proxima Centauri.

‘It’s a kind of technological signal. The question is whether it is Earth technology or technology from somewhere, ”said Sofia Sheikh, a graduate student at Pennsylvania State University, led by a team studying the signal and trying to decipher its origin. She is part of Breakthrough Listen, a $ 100 million effort funded by Yuri Milner, a Russian billionaire investor, to find foreign radio waves. The project has now stumbled upon its most intriguing payment dirt to date.

Proxima Centauri is an inviting prospect for ‘out there’.

It is the closest known star to the sun, only 4.24 light-years from Earth, which is part of a triple galaxy known as Alpha Centauri. Proxima has at least two planets, one of which is a rocky world that is only slightly more massive than the earth, which occupies the so-called habitable zone of the star, where the temperature on the surface of water, the things of life, must promote.

The radio signal itself, which was detected in the spring of 2019 and reported earlier in The Guardian, is in many ways the thing of dreams for alien hunters. It was a narrowband signal with a frequency of 982.02 MHz as recorded in the Parkes Observatory in Australia. Nature, whether an exploding star or a geomagnetic storm, tends to transmit at a wide range of frequencies.

“It seems like the signal only appears in our data when we look in the direction of Proxima Centauri, which is exciting,” Sheikh said. “This is a threshold that has never been crossed by a signal we’ve seen before, but there are many caveats.”

Practitioners of the hopeful field of the quest for extraterrestrial intelligence, also known as SETI, say they have seen it before.

“We’ve seen this type of signal before, and it always seems to be RFI, radio frequency interference,” Dan Werthimer, chief technologist at the Berkeley SETI Research Center, which is not part of the Proxima Centauri study, wrote in an article. email.

The thought was repeated by his Berkeley colleague Andrew Siemion, who is the lead investigator for Breakthrough Listen. “Our experiment consists of a sea of ​​disturbing signals,” he said.

“My instinct is ultimately that it will be anthropogenic in origin,” he added. “But so far we can not fully explain it.”

So here’s nothing to see, people. Until there is. Despite claims of biosignature gases on Venus and stories of UFO sightings collected by the Pentagon, the discovery of life, let alone intelligence, would be a psychological thunderbolt of cosmic and historical proportions.

False alarms were part of SETI from the beginning, when Frank Drake, then in Cornell and now retired from the University of California, Santa Cruz, in 1960 a radio telescope in Green Bank, W.Va., on a few stars hoping to hear strangers’ radio waves. He noticed what looked like a signal. Can it be so easy to discover that we are not alone?

It turns out to be a secret military experiment.

Sixty years later we are still officially alone and SETI as a business has endured the wars economically and politically, even though technology has the ability of mankind to comb the almost infinite haystack of planets, stars and ‘magical frequencies’ on which they would broadcast .

Breakthrough Listen was announced in 2015 with great fanfare by mr. Milner and Stephen Hawking, which led to what dr. Siemion called it a renaissance.

“This is the best time to do SETI,” he said.

The recent excitement began on April 29, 2019, when scientists broke through Listen to the Parkes radio telescope on Proxima Centauri turning to monitor the star for violent torches. It is a small star known as a red dwarf. These stars are prone to such eruptions, which can remove the atmosphere of a planet and make it uninhabitable.

In total, they recorded 26 hours of data. However, the Parkes radio telescope was equipped with a new receiver that could solve the narrowband signals of the kind that SETI researchers are looking for. In the fall of 2020, the team decided to search the data for such signals, a job that falls to Shane Smith, an undergraduate student at Hillsdale College in Michigan, and an intern at Breakthrough.

The signal that surprised the team appeared five times on April 29 during a series of 30-minute windows in which the telescope was pointed in the direction of Proxima Centauri. It has not appeared since. It was a purely unmodulated tone, meaning that it apparently carries no message other than the fact of its own existence.

The signal also tended to drift slightly in frequency at 30 minute intervals, a sign that everything the signal is coming from is not on the earth’s surface, but that it correlates with a rotating or rotating object. .

But the drift does not match the movements of any known planets in Proxima Centauri. And in fact, the signal, if it really is, comes from somewhere outside the Alpha Centauri system. Who knows?

The subsequent non-appearance of the signal has comparisons to a well-known detection known as the “Wow! Signal ”which appears on a print of the Big Ear Radio Telescope, operated in 1977 by Ohio State University. Jerry Ehman, a now retired astronomer, said “Wow!” on the side of the printout when he saw it. The signal never reappeared, nor was it satisfactorily explained, and some people still wonder if it was a missed call from out there.

Regarding the Proxima signal, dr. Siemion said: ‘There have been a few shouts, but’ wow ‘has not been one of them yet. ”

When asked what it is, he laughs.

“At first there were surprising reactions from people, but it quickly subsided,” he said.

Over a period of 24 to 48 hours at the end of October, he said, the state of mind shifted from curious and inquisitive to “very serious scientific detective work.”

Me. Sheikh, who expects her to earn a doctorate next summer, is leading the detective work. She earned her bachelor’s degree from the University of California, Berkeley and intended to study particle physics, but instead pursued astronomy. She first heard about the Breakthrough Listen project and SETI on Reddit while looking for a new undergraduate research project.

“I would say we were extremely skeptical at first, and I remain skeptical,” she said of the alleged signal. But she added that it was “the most interesting signal to get through the Breakthrough Listen program.”

The team hopes to publish its results in early 2021.

The Parkes telescope – which once transmitted communications to the Apollo astronauts – is notorious for false alarms, says Dr Werthimer. In one recent example, he said, astronomers think they have discovered a new astrophysical phenomenon.

“It was very exciting until someone noticed that the signals only appeared during lunch hour,” he said. They come from a microwave oven.

Over the years, SETI stargazers have been proud of their ability to chase down and eliminate the source of suspicious signals before the word was leaked to the public.

This time, their work was reported by The Guardian. “The public wants to know, we understand that,” said Dr. Siemion said. But like him and me. Sheikh emphasizes, they are not nearly finished yet.

“Honestly, there are still a lot of analyzes we have to do to trust that this thing is not interference,” she said. Sheikh said.

She explained that part of the problem is that the original observations were not done according to the standard SETI protocol. Normally, a radio telescope would point to a star or other target for five minutes and then nod slightly away from it for five minutes to see if the signal continues.

In the Proxima observations, however, the telescope showed 30 minutes and then moved five minutes far across the sky (about 30 degrees) to a quasar that the astronomers used to calibrate the brightness of the star’s torches. Such a large swing possibly took the telescope away from the source of radio interference.

If all else fails, Ms Sheikh will try to reproduce the results by repeating the exact movements of the Parkes Telescope again on 29 April 2021.

“Because,” she said, “if it’s actually from Proxima, they might want to say goodbye once a year or something.” She added: “But it’s more likely that there’s some kind of annual event happening in the visitor center, or something like that, causing an environmental impact that doesn’t happen the rest of the year.”

The Proxima signal may be destined to turn into legends like the Ohio State Wow! Signal, but in SETI there is always another day, another star.

It was nice, said me. Sheikh said, even if the Proxima signal is ultimately interference.

“It’s extremely exciting, no matter what comes out of it.”