SETI Has Existed Since 1960, but We Still Haven’t Detected Extraterrestrial Signals — Space Weather May be a Factor

As of today, NASA has confirmed the existence of more than 6,000 exoplanets (planets outside the Solar System), and scientists estimate that there are probably billions of planets in our galaxy alone. Some of these planets are similar to Earth, where liquid water could exist and an atmosphere that could support life.

So far, though, we haven’t heard a peep from anyone else in the universe. And it’s not for lack of trying. The search for extra-terrestrial intelligence (SETI) has been underway since 1960 with the advent of Project Ozma, an attempt to detect extraterrestrial radio signals. Almost 70 years later, there’s still no indication that we’re not alone.

Why Haven’t We Detected Any Extraterrestrial Radio Signals

There are many possible reasons for the silence. Perhaps alien civilizations are being careful to keep their presence a secret. Or maybe they’re out there, but not quite advanced enough to have detectable technology. Or perhaps their technology is so advanced we can’t recognize it.

But now researchers have another theory. Maybe radio signals from other planets are being blurred by space weather. That’s the idea behind a recent paper published in The Astrophysical Journal by Vishal Gajjar and colleagues at the SETI Institute, a nonprofit research organization that looks for life elsewhere in the universe.

When searching for radio signals from an extraterrestrial intelligence, scientists look for what they call a technosignature, Gajjal explained to Discover. A technosignature is something unlikely to have been produced by a natural process.

“We basically search across the entire electromagnetic spectrum,” Gajjal said.

SETI scientists look particularly for extremely sharp frequency spikes, because that kind of signal is easy to distinguish from natural astrophysical emissions.

Read More: New SETI Tool Expands the Search for Intelligent Life in the Universe

Space Weather and Signals

But what if that approach is missing something? Activity, or “space weather” — plasma turbulence and stellar winds, for example — in the area close to a planet’s star might interfere with the signal, effectively spreading the signal across a wider frequency range.

“When you observe it for a limited amount of time, it will not look like a stationary signal at a single frequency, but it will look like a spread-out signal across many frequencies,” Gajjal said.

Rather than looking like sharp spikes, or needles as he calls them, they show up as softer peaks.

This study suggests that researchers need to adjust their search strategy. They’ve been searching for these narrow spikes for the past 60 years or so, and haven’t detected anything. But they haven’t been looking for spread-out signals.

“One of the reasons that we’ve missed a signal of this nature could be because we were not looking for it,” Gajjal said.

Expanding the Search For Extraterrestrial Intelligence

M-dwarf stars, which make up around 75 percent of the stars in the Milky Way, are the type of star most likely to have space weather that spreads out those signals. They’re also the ones most likely to support planets with intelligent life.

“If you want to take a bet on where you are likely to find extraterrestrial life in the Milky Way galaxy, I would probably go near an M-dwarf star,” Gajjar said.

If they survive their early phase, these stars become stable and can remain so for a long time. A planet in the habitable zone of an M-dwarf star could have an extended period of atmospheric stability during which intelligent life could evolve. That’s why adjusting the search strategy to look for more spread-out signals could greatly improve the odds that we’ll find extraterrestrial intelligence sooner rather than later.

How much would the odds improve? That’s hard to say, said Gajjal. But it certainly improves the chances that searchers will detect a signal. And though it’s also hard to know if or when we’ll find extraterrestrial intelligence, Gajjal thinks the odds are slightly in our favor, thanks to advancements in technologies, particularly graphical processing units and machine learning, that help us analyze huge amounts of data much more efficiently.

Finding those signals of life would be more than an academic achievement, Gajjal said. It might make us appreciate each other more. Gajjal was moved by the images sent back from the Artemis II Moon mission.

“On Earth, we divide ourselves with all these boundaries, but in space, nothing really matters. We are just a speck in the dust, right?” he told Discover. “Extraterrestrial life is the same way. If you find life outside, all of our differences don’t really matter that much.”

Read More: If We Send Signals to the Right Spots in Deep Space, Aliens Could Hear Our Calls

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