Asteroid 2022 WJ1, discovered by the Catalina Sky Survey in November 2022, is the smallest asteroid to be characterized both in space and upon entering Earth's atmosphere. By using telescopic measurements and fireball imagery, the team revealed the asteroid's silicate-rich composition and estimated its diameter to be 40-60 cm (16-27 inches). This collaborative study establishes a new approach for analyzing future Earth-impacting objects.
"This is only the second time that an asteroid has been meaningfully characterized with telescopes prior to it impacting the Earth," explained Kareta. "It's a testament to our good luck and preparation, but it's also due to the community that cares about keeping the Earth safe from these impactors learning to work together better."
The LDT's observations showed that asteroid 2022 WJ1 reflected 20-30% of sunlight due to its silicate mineral content, classifying it as an S-type asteroid. These asteroids are stony bodies among the oldest in the solar system, often associated with ordinary chondrite meteorites that fall to Earth. Fireball camera data from Western University scientists confirmed these findings by tracking the asteroid's breakup in Earth's atmosphere above Toronto.
"This first-ever comparison between telescopic and fireball camera data is extremely exciting," said Kareta. "It means we'll be able to characterize the next asteroid to impact the Earth in even better detail."
Despite predictions that some fragments of the asteroid survived atmospheric entry, no meteorites have been recovered. Much of the debris likely fell into water, and any fragments on land have likely become indistinguishable over time. "We have no plans to do any official searching," said Dr. Denis Vida of Western University. However, locals in the region might still uncover meteorites by chance.
The asteroid's discovery allowed astronomers a narrow three-hour window to observe it before impact. The LDT's advanced tracking capabilities enabled Kareta and his team to monitor the asteroid's fast-moving trajectory until it faded into Earth's shadow. "At the time that we lost the asteroid - when it got too dim to be seen in our images - we had the telescope moving at five degrees per second to try to keep up with it," Kareta noted. "That's fast enough that most other telescopes would have had to give up considerably earlier."
Dr. Gerard van Belle, Director of Science at Lowell Observatory, commended the telescope's performance. "Because of the wide-ranging capabilities of the LDT, we were able to quickly acquire the asteroid and continue to observe it as it streaked across the sky. We are excited to be making it even better with our new Science Vision plan that will allow it see faster, fainter, and farther."
Reflecting on the event, Kareta added, "It's tremendously fortuitous that this asteroid happened to fly over Arizona's dark skies at night before burning up over Western's excellent camera network - it's hard to imagine better circumstances to do this kind of research."
Research Report:Telescope-to-Fireball Characterization of Earth Impactor 2022 WJ1
Related Links
Lowell Observatory
Asteroid and Comet Mission News, Science and Technology
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