As a highly respected astronomer, Harvard professor and former chair of Harvard’s astronomy department Avi Loeb made waves when he started talking and writing about extraterrestrial intelligence. He last came on GBH’s All Things Considered to discuss his idea that the strange, extrasolar object known as Oumuamua might have been an interstellar alien spacecraft. Since then, he’s become even more serious about searching for evidence of alien intelligence with his own organization and with the Pentagon. Loeb returned to All Things Considered and joined host Arun Rath to explain his research in detail.

Arun Rath: First off, give us a little bit of context on where we are with this situation. It was last summer when the Department of Defense created a new office to track unidentified aerial phenomenons — what we used to call unidentified flying objects or UFOs. But could you briefly explain what’s going on here, and why the Pentagon decided to get serious about this?

Avi Loeb: About half a year ago, the director of the new office in government that deals with anomalies wrote me an email and said that he is visiting the Boston area in the coming weeks and asked me whether I’m available to meet with him. I said yes, of course, and he came to my home. As a result of that, we wrote a scientific paper together in which we talked about the physical constraints that can be put on unidentified objects based on the limited data we have.

In this paper, we speculated about possible scenarios by which probes may be released toward the Earth; for example, from a mothership, because the second interstellar meteor had the same distance of closest approach to the sun. So more and more, I thought to myself, “Well, maybe it was released by a smaller probe released by a mothership.” But then it turned out to have originated from a different direction, and so they were not actually related.

But in the paper with Sean Kirkpatrick, we mentioned the possibility that the mothership would come by or pass near Earth — just like Oumuamua did — and release a lot of probes that can visit different planets in the habitable zone.

Rath: Based on what we’ve seen of some of these objects, I imagine there’s an argument to be made that this technology would be beyond any of our adversaries.

Loeb: Not necessarily. I think the government is confused. It’s unclear what the nature of these unidentified objects might be.

From a scientific point of view, the fundamental question is whether there is even one object that is of extraterrestrial technological origin. That’s what the Galileo Project that I established a year and a half ago is trying to find out.

We have an operating observatory at Harvard University that we assembled over the past year. It has infrared optical cameras and a radio and audio sensor that are monitoring the sky 24/7. The data is being fed to an artificial intelligence classification software that tries to figure out whether any of the objects we look at are natural in origin, like birds, or human-made objects, like drones, balloons or airplanes.

My approach to this puzzle is that rather than deal with past events that were anecdotally reported with compromised instruments that we can never revisit because the data was collected from months or years ago, it’s much better to have instruments that are fully under our control.

After all, the sky is not classified; it’s only the sensors that the government used that are classified that make the data classified. The best data is not available to us, to scientists, or to the public simply because it was collected by sensors that are classified that the government doesn’t want adversaries to be aware of.

Rath: How much has your project, the Galileo Project, been involved with the Pentagon office? Have you been sharing a lot of data?

Loeb: Well, the past couple of years were very interesting. After my book “Extraterrestrial” came out, a lot of high-level people came to my home. They included multibillionaires that funded the Galileo Project. They were inspired by the vision and the fact that there was no scientific search for technological devices near Earth from an extraterrestrial civilization, and also the fact that the first three out of four interstellar objects that were discovered over the past decade appear to be weird, unusual outliers relative to the rocks that we found from the solar system before the asteroids or the comets just over the past decade. We could find those objects that entered the solar system from outside with no survey telescopes, with no satellites the government employs.

The first two were meteors roughly the size of a meter that collided with the Earth and burned up in the Earth’s atmosphere. We realized that both of them arrived from outside the solar system. They were moving very fast. So we discovered the first two interstellar meteors.

Then, about seven months after the second one, there was the object, Oumuamua, which was discovered by a telescope in Hawaii. That object was much bigger, the size of a football field — about 200 times bigger than those meteors. It also looked weird because it had an extreme shape, most likely flat, and it was pushed away from the sun by some mysterious force without showing any cometary evaporation. There was no comet around it. I suggested it [the force] was the reflection of sunlight, and for that, the object had to be very thin, unlike the asteroids or comets we had seen before.

And actually, three years later, the same telescope in Hawaii discovered another object with no cometary tail, and it ended up being a rocket booster that NASA launched in 1966. It had thin walls and was made of stainless steel, so clearly, it was artificial in origin; that’s why it didn’t evaporate, and we know it because we produced it.

The question is: who produced Oumuamua, or the meteors? And I should say the meteors are also unusual in the sense that they are made of material that has a strength that is at least ten times bigger than all other space rocks in NASA’s catalog of meteors over the past decade. But it’s also possible that there are spacecrafts made of some artificial alloy, like stainless steel.

We’re going to find out. We’ve planned an expedition to the Pacific Ocean in the summer of 2023, and we will look for the fragments of the first interstellar meteor and try to figure out what it was made of.

Rath: So if you recover this object deep in the Pacific, will that be the first interstellar object that we’ve recovered?

Loeb: Yeah. It would be the first time that humans put their hands on the material that makes an object the size of a person from outside the solar system. So no matter what, it will be exciting. Since we expect its material strength to be quite unusual, we will learn something new, irrespective of whether it’s natural or artificial in origin. That’s why I find it exciting, and I’m willing to sleep on the deck next to the machine room for a couple of weeks this summer.