On January 8, 2014, a fireball from space flared through Earth's atmosphere and fell into the ocean, north of Manus Island off the northeastern coast of Papua New Guinea. Its location, speed and brightness are recorded by US government censors and secretly stored in a database of similar occurrences.
The data was stored for five years, without any source of contention until Avi Loeb, a theoretical astrophysicist at Harvard University, and Amir Siraj, an undergraduate student at the university, discovered it in 2019. Based on the speed and direction recorded, Pak Siraj identified the fireball as an extreme outlier.
Last month, Dr. Loeb led an expedition to retrieve fireball fragments from the ocean floor of the western Pacific. On June 21, he claimed that he has. And such discoveries, he says, to the chagrin of many of his colleagues, may be how scientists find evidence of extraterrestrial life.
“Not a biological creature, like you see in sci-fi movies,” said Dr. Loeb. “Most likely a technological gadget with artificial intelligence.”
However, many astronomers view the announcement as the latest example of Dr. Loeb who made a strange statement that was too forceful and too hasty. His statement (and promotion videos in Times Square about the search for extraterrestrial life) warp public perceptions of how science actually works, they say.
“People are sick of hearing about Avi Loeb's wild claims,” said Steve Desch, an astrophysicist at Arizona State University. “It taints good science – combines the good science we do with this ridiculous sensationalism and sucks all the oxygen out of the room.”
Dr. Desch added that some of his colleagues now refuse to get involved with Dr. Loeb in peer review, the process by which scholars evaluate one another's research to ensure that only high-quality research is published. “This is a real distraction from the peer review process and the scientific method,” he said. “And it's very demoralizing and exhausting.”
Dr. Loeb also began to study fireball catalog from the Center for Near-Earth Object Studies at NASA. That led to an object that had been detected in 2014. From the direction and velocity of the impact – 28 miles per second – Dr. Loeb and Mr. Siraj concluded that the fireball had moved too fast for something to be gravitationally bound to our sun. That means, like Oumuamua, it must also be interstellar.
They wrote a paper about the discovery in 2019. It was initially rejected by The Astrophysical Journal, but the same journal later accepted it for publication last November, months after the US Space Command announced in a memo circulating on Twitter that measurements of the fireball's velocity were accurate enough to infer an interstellar origin.
That appeal to the authorities is not enough, said Peter Brown, a meteor physicist at Western University in Ontario. It is not known how precise the US Department of Defense data is, which affects how likely the object is to have an outside origin.
“We know from experience, running ground-based radar and optical networks, that you often find a few percent of all the events you detect appear to be interstellar,” said Dr. Brown. Until now, he continued, almost all of these events could be attributed to measurement errors.
Brown and others are also annoyed by Dr. Loeb with a community of experts studying fast-flying fireballs.
Sea expedition Dr. Loeb's recent attempt to save the remains of the meteor was financed with $1.5 million from Charles Hoskinson, a cryptocurrency entrepreneur, and organized through EYOS Expedition. The voyage took place about 60 nautical miles north of Manus Island along the expected path of the 2014 fireball. A group of scientists, engineers and sailors and a film crew, as well as Mr. Hoskinson, accompanied Dr. Loeb. He has documented the voyage and its aftermath in 42 parts (and counting) a series of self-published blog posts.
For two weeks, the science team dragged a specially made sled equipped with magnets, cameras and lights across the ocean floor, periodically picking it up for bits of metal from the 2014 fireball stuck to its surface. In the end, they found a number of glittering beads, each less than a millimeter in diameter. Preliminary analyzes carried out on board indicated these spherules were made mostly of iron, with lesser amounts of other metals.
It is not commonly found in the waters around Manus Island, said Maurice Tivey, a marine geophysicist at the Woods Hole Oceanographic Institution who was not involved in the expedition but who has used underwater robots to map the area of the seafloor. In contrast, volcanic sediment and ash are very fertile — material that doesn't move much after it settles to the ocean floor.
That, combined with the roundness of the fragments found – suggesting they were once aerodynamic – seems pretty convincing to Dr. Tivey. “So I think he found the pieces,” he said.
Skepticism about the effort has flared recently Conference on Asteroids, Comets, Meteors that occurred while a deep-sea expedition was in progress. There, Dr. Desch argued that if the fireball had traveled as fast as reported, there would be nothing left to find – the meteor would have burned up completely in the atmosphere. Even in the most generous of scenarios, he says, only one milligram of material would survive, and it would be spread over tens of square kilometers along the ocean floor.
Dr. Brown also presented at the conference, explaining a recent analysis using data from multiple instruments to cross-check measurements for 17 objects listed in the same NASA fireball catalog used by Dr. Loeb and Mr. Siraj. Hers resultswhich has been accepted for publication in The Astrophysical Journal, shows that catalog data often gets the wrong direction and velocity and the size of the error for velocity measurements increases for objects with higher velocities.
The error was large enough to move the 2014 fireball from free orbit to bound orbit, Dr. Brown explained — meaning it's probably not interstellar. He found that if the object was actually traveling at speeds close to 12.5 miles per second upon impact, the reported brightness, density, and air resistance more closely match theoretical models of the meteor.
On that basis, Dr. Brown deduced that the fireball most likely impacted at a lower velocity. “If the velocity is exaggerated, then the object falls into, more or less, within the realm that we see in other bound solar system objects,” he said.
Dr. Loeb disagreed with the rejection.
“When I was trained as a physicist, I was told when you have a model and it doesn't fit the data, you have to revise your model,” he said, referring to measurements in the NASA catalog.
He also believes, unlike many of his colleagues, that US military censors can be trusted, even though he doesn't have access to the raw readings. “They are responsible for national security,” said Dr. Loeb. “I think they know what they're doing.” That he and his team found what they think to be fragments of the 2014 meteor at the location indicated by the measurements only fills him with confidence.
There is no way the government is going to declassify how precise the device data is. So Dr. Loeb relies on different evidence: He has sent the spherules to laboratories at Harvard University, the University of California, Berkeley, and the Bruker Company in Germany for analysis and rigorous dating. Spherules that are older than our solar system, or with a different isotope sign, must be interstellar.
At Berkeley, Dr. Loeb conducted the first few checks himself. Initial tests revealed the presence of uranium and lead, the abundance of which can be used to estimate the age of the material. Two of the spherules found along the expected fireball path appear to be as old as the universe itself, claims Dr. Loeb.
That was in contrast to the spherule being found far away from the fireball's path, which Dr. Loeb is of geological origin or from a different meteorite. He estimated this spherule to be several billion years old, comparable to that of our solar system.
But even if the fireballs really did originate from another cosmic environment, more evidence is needed to show that spherules are related to extraterrestrial life.
According to Don Brownlee, an astronomer at the University of Washington who used magnets to collect cosmic marbles from the ocean floor in the 1970s, if the spherules didn't contain nickel, they probably weren't natural meteorites. On the other hand, he said, if no oxygen is found, it is unlikely that the material will pass through the Earth's atmosphere. Dr. Loeb has written that initial results revealed the absence of nickel, but he did not mention oxygen.
He was open to the possibility that he was wrong, but he also liked to call out scientific figures in response to the problem. “Einstein got it wrong three times,” he said, referring to supermassive black holes, gravitational waves, and quantum entanglement — all discoveries for which he has since been recognized with a Nobel Prize in Physics. “It is invaluable to test ideas experimentally,” says Dr. Loeb. “Let the evidence be your guide.”
According to Dr. Desch, the meteor community does believe interstellar objects are out there, and they'd really like one to crash into Earth – there's no hard evidence yet that that has happened. “I just want to convince the public that scientists are not making it up,” he said. “What the public sees in Loeb is not how science works. And they shouldn't leave thinking that way.”
The public can hear more from Dr. Loeb about extra rock chunks from the ocean floor. Later this year, his team intends to return to Papua New Guinea's northern waters to hunt for the larger 2014 fireball relic. And in 2024, the team says it will visit a site off the coast of Portugal to search for remains from the second meteor that belonged to Dr. Loeb and Mr. Siraj. confirm interstellar origin.
“He may be wrong,” said Rob McCallum, co-founder of EYOS Expeditions and the main organizer of the recent expedition, adding, “but we'll never know unless we see him.”