Looming large before the search for extraterrestrial intelligence (SETI) is the UFO/UAP phenomenon. And the two ways of thinking about aliens are heading toward one another on an inevitable collision course.

The clash could forever change the way we do SETI.

Over the past few years, there’s been a sea-change in attitudes towards ufology. Maybe it’s just that The X-Files generation has now grown up, but believing in UFOs (or UAP, unidentified aerial phenomena, an acronym that apparently carries less stigma than UFOs or flying saucers but which really refers to the same thing) has become buzzy.

The topic reached critical mass after Harvard Astronomer Avi Loeb’s contestable claims that the interstellar object 1I/‘Oumuamua was a spacecraft rather than an asteroid or comet. And whereas once upon a time you were made a social outcast for even suggesting that aliens could be real, today you could be mocked on social media if you don’t believe that the infamous videos released by the Pentagon show alien spacecraft buzzing US Navy fighter jets.

How to confront this new reality is a challenge for the SETI community. With the announcement that NASA has launched their own study into UAPs, but on the back of a US Department of Defense investigation and hearings in the United States Congress where earnest politicians were imploring Pentagon officials to make UAP research a priority, SETI could suddenly find itself playing second fiddle in the minds of politicians and the public. With funding for SETI being as scarce as it is, losing out on funds to ufology is not a place SETI wants to be.

The key difference between SETI and ufology, frankly, is that one is grounded in the scientific method, whereas the other is frequently based on wishful thinking. And grainy footage.

We’ve seen how SETI approaches a potential detection of alien life in recent years, with the saga of the mysterious radio signals detected by the Breakthrough Listen project that was apparently coming from Proxima Centauri. The media and public became very excited, but Breakthrough Listen scientists remained calm. In science, a hypothesis is created to attempt to explain a dataset. In order to validate that hypothesis, one then tries everything possible to disprove it, because that’s the only way you can be confident that it is correct. After all, you don’t want to claim you’ve discovered aliens, only to later be shown that you were wrong. So terrestrial explanations for the Proxima Centauri signals were sought and eventually found, and the mystery was explained away. It might not have made headlines, but it was good science.

Unfortunately, UAP enthusiasts rarely adhere to the same rigor. One only has to look at the sensationalist reaction to the Pentagon videos to realize that people leap like an Olympic hurdler to their desired conclusions without even giving the slightest thought to more mundane, but more likely, explanations, of which there are several. (These include incursions into US air space by advanced drones belonging to a foreign power, products of the United States’ own black projects, ‘ghost’ images produced by forms of electronic warfare or laser infrared countermeasures that neatly describe what was actually observed.)

So the SETI community may be forced to follow the crowd, but it shouldn’t sacrifice its scientific principles in doing so.

However, now is the perfect time for an old idea in SETI to get its share of the limelight. It may surprise some readers, but SETI scientists have been talking about interstellar visitors to our Solar System for as long as they’ve been doing SETI.

The year 1960 was a groundbreaking one for the scientific search for extraterrestrial life. Not only was it the year when SETI became an experimental science with Frank Drake’s historic Project Ozma radio search, but it was also the year for two crucial theoretical advances in the field too. One was Freeman Dyson’s eponymous concept for spherical swarms of solar collectors encapsulating stars. The other was devised by renowned Australian physicist Ronald Bracewell, who speculated in a paper in Nature that extraterrestrial societies may have sent robotic probes to our Solar System.

Like the Dyson sphere, this concept was also named after its progenitor, and such hypothetical probes became known as Bracewell probes.

This, remember, was just three years after the launch of Sputnik. While the world was still lauding the achievement of reaching Earth orbit, Bracewell was already thinking on an interstellar scale.

“Each probe would be sent into a circular orbit about one of [a] thousand stars, at a distance within the habitable zone of temperature,” Bracewell wrote in his 1960 paper. “Armored against meteorites and radiation damage, and stellar powered, the probes could contain durable radio transmitters for the purpose of attracting the attention of technologies such as ours.”

His ideas sparked the imagination of a few scientists — Bracewell probes became merged with John von Neumann’s idea for self-replicating robots — and even more science-fiction writers, such as Fred Saberhagen and his novels about destructive Berserker probes, and Arthur C. Clarke’s more peaceful Monolith from 2001: A Space Odyssey and its sequels. But the SETI community focused on radio searches and largely left the idea on the sidelines.

Though Bracewell probes occasionally featured in blue-sky thinking about how long it would take for self-replicating robots to settle the entire galaxy, actual experimental searches for them in our Solar System were few and far between, with the work (and occasional controversial claim) of Scottish amateur astronomer Duncan Lunan being the most notable.

Yet the concept of Bracewell probes is proving more valid than ever. After all, we explore our own Solar System with robots — the Voyagers are still communicating with us having left the heliosphere — and we have plans to send probes across interstellar distances at some point this century. Even a species just a few hundred years more technologically developed than we are could have launched probes to explore the galaxy.

So to stay in the game, SETI needs to embrace searches for Bracewell probes in the Solar System just as it does searches for techno signatures beyond our Solar System. Put them front and center, and let them be SETI’s answer to the UAP craze. It would certainly be different compared to listening patiently for a radio message, but it might just be the shot in the arm SETI needs to face this attention and funding challenge from UAP.

Indeed, some scientists have already begun looking. Previously I wrote about one such search for anomalous objects in Earth orbit, scouring archived data from before the dawn of the Space Age. That search did find some odd sightings that deserve to be investigated further — following the scientific method, of course.

But where do we stop? If we accept that the possibility of there being a Bracewell probe, or probes, in our Solar System is scientifically valid, is it then such a huge stretch to imagine that they might occasionally enter our atmosphere to take a closer look? And if we accept that, is it a slippery slope to accepting reports of abductions or cattle mutilations or crop circles as being worthy of our time for scientific study?

Clearly, the lines are about to get seriously blurred, and it will be fascinating to see how things play out over the next few years, and how scientists and the media will handle it. Where should the line be drawn between valid scientific inquiry and wasteful science fiction speculation? Can there even be a clean dividing line anymore? And, depending on how far SETI strays into UAP investigations, will it harm SETI’s reputation in the scientific community at large? (And let’s face it, SETI has not always been held in the highest regard by other scientists, even at the best of times.)

There’s another wrinkle. There’s been a big debate about whether we should reply to a SETI signal if we ever detected one, or whether we should be transmitting our own messages into space. That debate becomes even more pertinent when we’re talking about an alien correspondent not light years away, but in our own Solar System. If we’re serious about searching for Bracewell probes, then we have to consider what would happen if we found one, particularly if it was still active.

Say an advanced extraterrestrial probe was discovered lurking, watching us, from the Moon, or a near-Earth asteroid, or a Lagrange point, what would our reaction be to an essentially first-contact situation?

There are a lot of ways that things could go wrong. Nations and billionaires and multinational companies will race to retrieve the probe, take it apart, learn its secrets, and profit from it. Yet the probe might not willingly be captured or dismantled and may be programmed to defend itself if necessary.

And how would we feel if we discovered that another civilization was effectively spying on us? Would we consider it an invasion of our privacy? Would we be suspicious of the entities that sent the probe?

Interestingly, while David Spergel — the world-renowned astrophysicist heading up NASA’s UAP study — has described how the study’s “first task is simply to gather the most robust set of data we can … from civilians, government, non-profits, companies …” he doesn’t mention utilizing astronomical data. Yet he could do a lot worse than to dust off Bracewell’s old concept of interstellar probes.

“Such a probe may be here now, in our Solar System, trying to make its presence known to us,” wrote Bracewell in 1960. Six decades later, SETI could now finally embark on a thorough search for one.

Just in case Bracewell was right.