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An object from another star system crashed into Earth in 2014, the United States Space Command (USSC) confirmed in a newly-released memo.
The meteor ignited in a fireball in the skies near Papua New Guinea, the memo states, and scientists believe it possibly sprinkled interstellar debris into the South Pacific Ocean. The confirmation backs up the breakthrough discovery of the first interstellar meteor—and, retroactively, the first known interstellar object of any kind to reach our solar system—which was initially flagged by a pair of Harvard University researchers in a study posted on the preprint server arXiv in 2019.
Amir Siraj, a student pursuing astrophysics at Harvard who led the research, said the study has been awaiting peer review and publication for years, but has been hamstrung by the odd circumstances that arose from the sheer novelty of the find and roadblocks put up by the involvement of information classified by the U.S. government.
The discovery of the meteor, which measured just a few feet wide, follows recent detections of two other interstellar objects in our solar system, known as ‘Oumuamua and Comet Borisov, that were much larger and did not come into close contact with Earth.
“I get a kick out of just thinking about the fact that we have interstellar material that was delivered to Earth, and we know where it is,” said Siraj, who is Director of Interstellar Object Studies at Harvard’s Galileo Project, in a call. “One thing that I'm going to be checking—and I'm already talking to people about—is whether it is possible to search the ocean floor off the coast of Papua New Guinea and see if we can get any fragments.”
Siraj acknowledged that the odds of such a find are low, because any remnants of the exploded fireball probably landed in tiny amounts across a disparate region of the ocean, making it tricky to track them down.
“It would be a big undertaking, but we're going to look at it in extreme depth because the possibility of getting the first piece of interstellar material is exciting enough to check this very thoroughly and talk to all the world experts on ocean expeditions to recover meteorites,” he noted.
Siraj and study co-author Avi Loeb, who serves as Frank B. Baird, Jr. Professor of Science at Harvard University, were inspired to search for potential interstellar fireballs in the wake of the discovery of ‘Oumuamua, an interstellar object measuring about a quarter mile that was spotted hurtling out of the solar system in 2017. Loeb, who has famously speculated that ‘Oumuamua might have been a piece of alien technology, suggested that Siraj comb through a database of fireballs and meteor impacts run by NASA’s Center for Near Earth Object Studies (CNEOS).
There are nearly 1,000 impacts logged in the database, but a fireball that exploded near Manus Island on January 8, 2014 jumped out at Siraj due to an unusually swift speed exceeding 130,000 miles per hour. This breakneck pace hinted at “a possible origin from the deep interior of a planetary system or a star in the thick disk of the Milky Way galaxy,” according to the team’s 2019 study.
“It was really fast, and so I was like: ‘Oh my God, this could be an interstellar meteor,’” Siraj said. “It was hiding in plain sight. It wasn't that we had to dig to find this database. It was more that there hadn't been an interstellar object until 2017. As a result, no one had a reason to think that there could be meteors that were from outside of the solar system.”
Siraj and Loeb submitted the discovery to The Astrophysical Journal Letters, but the study became snarled during the review process by missing information withheld from the CNEOS database by the U.S. government.
Some of the sensors that detect fireballs are operated by the U.S. Department of Defense, which uses the same technologies to monitor the skies for nuclear detonations. As a result, Siraj and Loeb couldn’t directly confirm the margin of error on the fireball’s velocity.
The secret data threw the paper into limbo as the researchers sought to get confirmation from the U.S. government. Siraj called the multi-year process a “whole saga” as they navigated a bureaucratic labyrinth that wound its way though Los Alamos National Laboratory, NASA, and other governmental arms, before ultimately landing at the desk of Joel Mozer, Chief Scientist of Space Operations Command at the U.S. Space Force service component of USSC.
The newly released memo, which is dated March 1 of this year, reveals that Mozer at last “confirmed that the velocity estimate reported to NASA is sufficiently accurate to indicate an interstellar trajectory.” Siraj found out about the results this week due to a tweet from a NASA scientist, and is now renewing the effort to get the original discovery published so that the scientific community can follow-up with more targeted research into the implications of the find.
For instance, Siraj noted that any information about the light emitted by the object as it burned up in the atmosphere could yield insights about the interior composition of the interstellar visitor. Indeed, scientists may have already glimpsed the spectral trace of an intergalactic meteor particle—yes, a particle from beyond the Milky Way—according to a study published in 2007.
While this was an incredibly small object, it indicates that the solar system may be awash in material from other star systems, and indeed even other galaxies, that could be turned up by future searches. Such efforts could offer a glimpse of the worlds beyond the Sun right here on Earth, and perhaps even unearth bonafide interstellar meteorites.
“Given how infrequent interstellar meteors are, extra-galactic meteors are going to be even rarer,” Siraj cautioned. ”But the fact of the matter is, going forward, we won't find anything unless we look for it. We might as well take it upon ourselves as scientists to build a network as extensive as the U.S government's sensor network, and use it for the purposes of science and fully use the atmosphere.”
“The atmosphere is already a sensor for these things,” he concluded. “We're just not paying attention to the signals. So we might as well use the whole atmosphere and see what comes our way.”