Spy satellites confirmed our discovery of the first meteor from outside the solar system News and Research

Spy satellites confirmed our discovery of the first meteor from outside the solar system News and Research

On January 8, 2014, at 5:05:34 PM UT, a six-foot rock shot from space off the coast of Manus Island, Papua New Guinea, burning with an energy equivalent to about 110 tons of TNT and raining debris into the depths of the Pacific. Similar sized fireballs are not uncommon in Earth’s skies; in fact, several dozen occur each year. But what was unusual about this particular meteor was the very high speed and unusual direction in which it encountered our planet, which together indicated that it came from interstellar space.

Sensors on a secret US government satellite designed to detect foreign missile launches were the only known witnesses to the fireball. Thanks to a partnership between the Department of Defense and NASA, the data describing the event was eventually shared in a public database hosted by the Center for Near Earth Object Studies (CNEOS) within the space agency’s Jet Propulsion Laboratory, along with data from more than 900 other fireballs recorded by US government sensors between 1988 and the present. The data for these events includes dates, times, latitudes, longitudes, altitudes, velocities, three-dimensional velocity components, and energies for each. Notably left out of the database are the uncertainties for most of these measurements – presumably to ensure that the precision thresholds for the US’s global detection capabilities are not revealed, as this information could potentially be misused by adversaries.

My involvement with this meteor dates back to April 2019, when my academic advisor at Harvard, astrophysicist Avi Loeb, brought the CNEOS fireball catalog to my attention. At the time, he and I spent about eight months studying data related to ‘Oumuamua, the object identified in October 2017 as the first known interstellar visitor to the solar system. Since ‘Oumuamua comes from outside the solar system, each of its properties, including its detection, has conveyed previously inaccessible information about our cosmic environment. With the wealth of knowledge of interstellar visitors most important in our minds, Loeb and I had been thinking about the possibility of finding others to study, and the CNEOS data looked promising. Within days, I had identified the 2014 Manus Island fireball as a potential interstellar meteor candidate. Loeb then suggested that I use the impact velocity combined with knowledge of the kinematics of small-body populations in the Solar System to estimate the probability that it came from elsewhere, outside of our Solar System. In considering this approach, I proposed a more accurate method of inferring the object’s orbit that explains the gravitational influences of our sun and its planets. Loeb agreed to my proposal and I quickly got to work.

At Earth’s distance from the sun, any object moving faster than about 42 kilometers per second is in an unconfined, hyperbolic orbit relative to our star, meaning it’s too fast for the sun’s gravity to move. fixed. So anything that exceeds this local celestial speed limit can originate from (and return unimpeded to) interstellar space. The CNEOS entry for the 2014 Manus Island fireball indicated that the meteor hit Earth’s atmosphere at about 45 kilometers per second — promising. However, part of this speed came from the object’s motion relative to the Earth and the Earth’s motion around the sun. When I took these effects apart using computer programs I wrote, I found that the object had overtaken the Earth from behind before hitting our atmosphere, and was probably moving closer to 60 kilometers per second relative to the sun. . The corresponding orbit I calculated was clearly untethered from the sun – even if there had been large uncertainty errors. If the data were correct, this event would be the first interstellar meteor ever discovered. And it hid in plain sight.

Extraordinary claims, of course, require extraordinary evidence. So Loeb and I reverse engineered estimates of the measurement errors of the classified satellites, using independently verified data on other fireballs in the CNEOS database and elsewhere in the scientific literature. After this painstaking reality check, we came to the same astonishing conclusion: The 2014 fireball clearly came from interstellar space. In a short period of time, we prepared a paper reporting our discovery for peer-reviewed publication.

Journal referees objected to the unknown nature of the error bars, so we enlisted the help of Alan Hurd and Matt Heavner, Los Alamos National Laboratory scientists with high security clearances, as well as an interest in fostering collaboration with the public sector to make blue sky science possible. In a short time, Heavner contacted the anonymous analyst who derived the meteor’s velocity components from the classified satellite observations, and confirmed that the relevant uncertainties for each value were no more than 10 percent. Plugging into our error analysis, this implied an interstellar origin with 99.999 percent certainty, but the paper was again rejected by arbiters, who objected that the uncertainty statement was a private communication with an anonymous U.S. government official, and not an official statement from the US government, which Heavner had difficulty obtaining. After several failed attempts to break through the veil of secrecy to the satisfaction of magazine reviewers, we sadly turned to other research, leaving the true nature of the 2014 meteor unconfirmed.

A year later, however, we were approached by Pete Worden, the president of the Breakthrough Prize Foundation, with an introduction from Matt Daniels, who at the time was working for the Office of the Secretary of Defense. Daniels had read our 2014 meteor preprint and wanted to help confirm its origin from the US government. After a year of arduous navigating through multiple layers of government bureaucracy, Daniels was able in March/April 2022 official confirmation from Lieutenant General John Shaw, deputy commander of the US Space Force, and Joel Mozer, chief scientist of the division’s Space Operations Command, about the relevant uncertainties – thus effective confirmation that the meteor was of real interstellar origin.

Three years after our original discovery, the first object to come from outside the Solar System and observed to hit Earth – the first known interstellar meteor – has been officially recognised. The 2014 meteor is also the first recorded interstellar object detected in the Solar System, more than three years older than ‘Oumuamua, and is one of three interstellar objects confirmed so far, alongside ‘Oumuamua and the interstellar comet Borisov.

The interstellar nature of the 2014 object has fascinating implications. Its size means that each star must contribute a significant mass of similar objects over its lifetime to make its detection likely in 2014 — suggesting many more interstellar meteors to be found. And its high velocity relative to the average velocities of our neighboring stars suggests it could have been ejected from another planetary system relatively close to its star. This is surprising, since you would naively expect that most interstellar objects would instead come from much more distant circumstellar regions where escape velocities are lower, namely the clouds of comets that are on the edge of many galaxies.

This new field, the study of interstellar meteors, certainly has a lot to tell us about our place in the cosmos. Closer examination of the observed features of the 2014 meteor could provide new insights into our local interstellar environment, especially when compared to the features of its successors, ‘Oumuamua and Borisov. Meteor databases are ripe for follow-up studies and there are new motivations for building new detection networks, with a focus on detecting future interstellar meteors. Observing an interstellar meteor burning in real time would allow for the study of its composition, providing new insights into the chemistry of other planetary systems.

The holy grail of interstellar object studies would be to obtain a physical sample from an object that comes from outside the solar system — a goal as daring as it is scientifically groundbreaking. We’re currently investigating whether a mission to the bottom of the Pacific Ocean off the coast of Manus Island, hoping to find fragments of the 2014 meteor, might be fruitful or even possible. Any large enough interstellar meteor discovered in the future should also produce a shower of debris, which we could potentially track down and analyze. There is, of course, another way to get samples, which I, as director of interstellar object studies for the Galileo project, also like to pursue: an encounter with a spacecraft. In collaboration with Alan Stern, the principal investigator on NASA’s New Horizons mission, we have now received funding to develop a concept for a space mission to a future interstellar object.

Like exotic seashells, these messengers from the stars have been washing up on our planetary beach for billions of years, each with secrets of their – and our – cosmic origin. Now we are finally starting to comb the coastline.

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