Credit:

Anibal Martel/Anadolu Agency via Getty Images

Reanalysis of a meteor that fell to Earth has cast some doubt on its origin—and its final destination.

This much is certain: on January 8, 2014, an object now catalogued as CNEOS 2014-01-08 entered Earth’s atmosphere somewhere overhead off the northern coast of Papua New Guinea in the South Pacific, heating to become a blazing, shockwave-generating fireball during its plunge from space. Such events are not rare; meteors enter our atmosphere all the time. But estimates of the object’s speed, touted at some 45 kilometers per second, led to suggestions that it might be interstellar in origin—a space rock from some alien and distant planetary system. While we have seen interstellar objects passing through our solar system before, no such objects were known to have ever made planetfall on Earth. So interest in CNEOS 2014-01-08 was piqued, given that its fragments could potentially offer a first direct sample of material sourced from another star.

In June 2023 Avi Loeb—a theoretical physicist at Harvard University—mounted a $1.5-million expedition to find pieces of the meteor. Loeb has been the leading proponent of the notion that this meteor was indeed interstellar in origin—and has even speculated that it may be linked to putative alien spacecraft. His recovery expedition—which was part of his UFO-studying Galileo Project—became a public sensation, further padding Loeb’s already long list of high-profile media spots, which included interviews on prime-time national television shows and with the easily enraptured podcast host Joe Rogan. Loeb has written countless blog posts and a bestselling book on his unorthodox approach to studying extraterrestrial life and intelligence. He has even gone so far as to appear on a giant billboard in Times Square promoting the Galileo Project’s efforts to find the interstellar meteor fragments.

His approach to the topic has, at times, been abrasive, and many other astrobiology-inclined researchers have found his sensational claims too difficult to parse and potentially damaging to their field. But as with any scientific investigation, particularly with findings as provocative as those suggested by Loeb, there is invariably interest in trying to find flaws in the methodology and to offer alternative, more plausible solutions. This latest episode is no exception; it focuses on one very specific data point from this purported interstellar object.

Loeb’s recovery expedition used a boat-dragged magnetic “sled” to scrape samples of sediments from strips of seafloor in an 11-kilometer-wide square where the team believed the meteor had fallen. That zone of inquiry primarily emerged from triangulating the meteor’s presumptive debris field using sensor data from a classified network of U.S. military satellites that were scrubbed of sensitive details and made public as part of NASA’s Center for Near Earth Object Studies (CNEOS). Loeb’s pinpointing also used a local seismometer on Manus Island, Papua New Guinea, which recorded vibrations from an event around the time the meteor supposedly entered the atmosphere to reduce the search area to a strip that was one-kilometer wide.

After studying those seismometer data, however, Benjamin Fernando, a planetary scientist at Johns Hopkins University, has concluded that Loeb’s analysis was flawed. The seismometer, Fernando says, recorded not a celestial object but something much more mundane and closer to home—a passing heavy truck—meaning that the location Loeb and his team searched would not have been in the path of the falling object. “We think that what they picked up from the seafloor is nothing to do with this meteor at all,” says Fernando, who posted the research on the preprint server arXiv.org and presented it at the Lunar and Planetary Science Conference (LPSC) in Texas on Tuesday, March 12.

Fernando and his colleagues maintain that the seismic spike used by Loeb’s team was decidedly similar to other signals likely caused by “cultural noise”—that is, vibrations from vehicles and other hefty, human-made sources. A signal’s polarization can be used to estimate the direction of the source, and in this case, it suggested a movement from “southwest to north over about 100 seconds,” Fernando says. That matches the orientation of a road near the seismometer that runs to a local hospital and aligns with another matching signal that perhaps came from the same vehicular source that was detected earlier in the day (when no known fireballs were overhead). “It’s actually just a truck driving by,” he says. Using information from a separate network of infrasound sensors meant to look for clandestine atomic explosions as part of the Comprehensive Nuclear-Test-Ban Treaty, Fernando and his team provide a different entry point for the meteor some 170 kilometers from where Loeb’s group searched. They also argue that the meteor mostly burned up in the atmosphere anyway, scattering few, if any, notable pieces onto the land or sea below. “You wouldn’t go looking for bits of a firework,” Fernando says.

Loeb vigorously disputes the claims. He says his team’s analysis was based not just on the seismometer but predominantly on the CNEOS data sourced from the U.S. Department of Defense (DOD). Even without those seismic data, he says, his group would have searched the same area. “What this paper by Fernando is doing is saying, We don’t believe the Department of Defense,” he says. “So I ask these astronomers: If you’re willing to say that, how can you sleep at night? You are saying, basically, that the entire national security infrastructure is not working. If we remove the seismometer data, we would still survey the DOD region, which is what we did.” He admits, however, that the Manus Island seismic data did notionally constrain the initial CNEOS-derived, 11-kilometer-wide debris field region to a much narrower strip. Despite this potentially sharper localization, Loeb says, his team still “crisscrossed the entire region” to collect samples. Fernando, in response, says there were two possible locations given for the meteor’s entry point from the DOD data, and even then, there were still big uncertainties. “It probably wasn’t going nearly as fast as they think it was” as calculated from the satellite data, he says, which casts significant doubt on an interstellar origin. “That was probably a measurement error.”

The nature of the samples is also hotly debated. In research presented prior to Fernando’s talk at LPSC, Hairuo Fu, a graduate student at Harvard, explained that the team had collected spherules displaying an unusual—and apparently unearthly—mix of elemental abundances. “We think the samples reflect a highly differentiated, extremely evolved composition of currently unknown origin,” he said. The talk became extremely uncomfortable during a subsequent Q&A, however, when Fu was bombarded with questions on the validity of that research without any of his more senior co-authors in attendance to back him up. At LPSC, Steven Desch, an astrophysicist at Arizona State University and co-author on Fernando’s paper, said the spherules were a “dead ringer” for material not from an interstellar meteor but a prior impact that is thought to have occurred nearly one million years ago in Southeast Asia, which would have thrown terrestrial material into the atmosphere and ocean. He says that if a proper “control” result was taken by Loeb’s team well outside the researchers’ zone of inquiry yet still geographically close by, that could have alleviated concerns. “If they want to associate these things with the meteor, why didn’t they also collect from 100 kilometers away?” he says. During the LPSC discussions, Fu said the group did take a control sample—but Desch countered that it was not substantial enough in volume or distance.

Elisa Dong, a geophysicist at York University in Ontario, says the response to Fu’s talk was “a little harsh” and adds he made “a really good argument,” although she was unsure about some of the analysis. Even if the samples collected by Loeb’s team did not come from the 2014 meteor, there is still useful science to be done in collecting material from the seafloor, she notes. “It’s astoundingly expensive,” she says. “You could not convince an institution to do this without very good reason.” Ellie Sansom, a planetary scientist at Curtin University in Australia and a co-author of Fernando’s paper, says that tracking incoming meteors with fireball networks is also a fledgling and worthwhile area of science. “Trying to work out how things come through our atmosphere, where they’re coming from and where they’re going to land is really exciting,” she says.

In terms of working out the entry of this specific meteor, the research presented by Fernando was “credible and very logical,” says Christian Koeberl, a geoscientist at the University of Vienna. “I’d say the earlier analysis was more driven by vivid imagination rather than factual knowledge and proper data treatment.” He adds that even if Loeb and his group had surveyed in the right area, there would be “no way to assign any spherules to any specific deposition event” because “the slow deposition in the oceans means there is aggregated material from thousands of years or longer at any particular place.” The whole situation has “resulted in opinions being made very public and often in personal ways that do no service to science,” says Caleb Scharf, an astrobiologist at NASA’s Ames Research Center. “It is easier to sort out the truth when time is not being spent on scoring rhetorical points and results are not being clouded by premature statements to the public. I’m sure that there are elements of fact scattered across all sides of this saga, but I also suspect that those elements of fact are not evenly distributed.”

Loeb, for his part, has already penned a partial rebuttal to Fernando’s preprint and intends to keep on trucking. Next up, he says, is a more detailed study of isotopes within the recovered spherules, which could further boost or diminish his team’s “interstellar” hypothesis. But whether any further investigations would change the minds of Loeb’s critics is another matter. Fernando sums up his opinion bluntly: “I think they’ve found some sludge,” he says.

Quelle: SCIENTIFIC AMERICAN