Astronomers searching for the origins of a small asteroid that exploded over the Pacific Ocean in September 2020 have found an archive picture of it, in space, taken minutes before the impact, in the first discovery of its kind.
at the University of Western Ontario in Canada and his colleagues analysed satellite data of previous major fireballs, identifying ones created by space rocks that would be big enough to show up in images from telescopic surveys, which routinely monitor the skies. After calculating the orbital path of each candidate space rock prior to it hitting Earth, the team then scoured archive imagery of patches of sky where it might have been caught on camera.
They had one success. For a 0.4-kiloton fireball that exploded over the Pacific Ocean in September 2020, the group found what they believe is the trail of an unknown asteroid in archival data from the Asteroid Terrestrial-impact Last Alert System project. Crucially, studying this imagery allowed the researchers to glean more information about the space rock than was revealed by its swan-song fireball.
Advertisement
鈥淲e were able to better define the original orbit, acquired hints on shape, and were able to measure its magnitude, giving us constraints on how its size and surface brightness relate,鈥� says Clark.
The finding means that a total of six Earth-impacting asteroids have now been observed in space, but this is the first to be uncovered in archival data after its impact had already occurred. The other five were all discovered and examined before they slammed into our atmosphere.
Work like this can help astronomers learn more about near-Earth asteroids, including their composition and what risk they pose, says Clark, who intends to carry on the project by searching in updated satellite and sky-survey data.
鈥淐ontinuing exploring the fireball archive would help us locate more interesting carbon and volatile-rich meteoroids in the future,鈥� says at Royal Holloway, University of London. 鈥淚f we are lucky enough, perhaps one of them could have arrived at a shallower angle and fallen in a dry desert for us to retrieve.鈥�
Reference:
Sign up to our free Launchpad newsletter for a voyage across the galaxy and beyond, every Friday
