2022 WJ1 was a small asteroid on a collision course with Earth. But astronomers saw it coming, and NASA’s Scout Impact Hazard Assessment System calculated where it would collide.
In the early hours of Saturday, November 19, the sky over southern Ontario, Canada, lit up as a small, harmless asteroid streaked through the sky high in Earth’s atmosphere, crashing, and possibly scattering small meteorites over the southern coast of Lake Ontario. Fireball was no surprise. The asteroid is about 1 meter (3 feet) wide, and was detected 3 1/2 hours before impact, making this event the sixth time in history that a small asteroid has been tracked in space before impacting Earth’s atmosphere.
NASA is tasked with detecting and tracking NEOs that could survive passing through Earth’s atmosphere and causing damage on Earth, but these objects can also be detected much earlier than small objects like an asteroid that broke up over the south. Ontario. Such small asteroids pose no danger to Earth, but they could be a useful test of NASA’s planetary defense capabilities for detection, tracking, orbit determination, and impact prediction.
“The planetary defense community really demonstrated their skill and preparedness with their response to this short alert event,” said Kelly Fast, program manager for Near-Earth Object Observations for the Planetary Defense Coordination Office (PDCO) at NASA Headquarters in Washington. “Such harmless impacts become automatic exercises in the real world and give us confidence that NASA’s planetary defense systems are able to inform the response to the possibility of a dangerous impact by a larger object.”
The asteroid was discovered by the NASA-funded Catalina Sky Survey, based at the University of Arizona in Tucson, on the evening of November 18 during its routine near-Earth object searches. The observations were quickly reported to the Minor Planet Center (MPC) – the internationally recognized clearinghouse for measurements of the positions of small celestial bodies – and then the data was automatically posted to the NEO confirmation page.
NASA’s Scout Impact Risk Assessment System, managed by the Center for Near-Earth Object Studies (CNEOS) at the agency’s Jet Propulsion Laboratory in Southern California, automatically fetched new data from that page and began calculating the object’s likely trajectory and chances of impact. . CNEOS calculates every known near-Earth asteroid orbit to provide assessments of potential collision risks in support of NASA’s PDCO.
Seven minutes after the asteroid was posted to the confirmation page, Scout determined it had a 25% chance of hitting Earth’s atmosphere, with potential impact sites stretching from the Atlantic Ocean off the eastern coast of North America to Mexico. Then more observations were made available by the astronomical community, including amateur astronomers in Kansas, to better refine the asteroid’s trajectory and potential impact site.
“Small objects like this one can only be detected when they are very close to Earth, so if they are destined for a collision, time is necessary to collect as many observations as possible,” said Shantanu Naidu, a navigation engineer and scout operator at JPL. “This object was detected early enough that the planetary defense community could provide more observations, which Scout then used to confirm the impact and predict where and when the asteroid will hit.”
As Catalina continues to track the asteroid over the next few hours, Scout used this new data to continually update the asteroid’s trajectory and assess the system for chance of impact, and publish those results on the Hazard Assessment System’s web page.
Many astronomers check the Scout webpage throughout the night to identify the most important asteroids to track. A group of amateur astronomers at the Farpoint Observatory in Escridge, Kansas, tracked the asteroid for more than an hour, providing critical additional data that enabled Scout to confirm a 100% probability of impact and pinpoint the expected location of the atmospheric entry as over southern Ontario at 3:27 a.m. EDT (12:27 a.m. PST) on November 19. With more than two hours to go before impact, there was time to alert scientists in southwestern Ontario to the bright fireball that might occur.
A total of 46 observations of the asteroid’s location were eventually collected, and the last observation was made just 32 minutes before the University of Hawaii’s 88-inch (2.2-meter) telescope impacted Mauna Kea.
As expected, at 3:27 a.m. EDT (12:27 a.m. PST) the asteroid penetrated Earth’s atmosphere at a shallow angle and broke apart, likely resulting in a shower of small meteorites and leaving no damage on the surface. After this harmless breakup, the Minor Planet Center located asteroid 2022 WJ1 to acknowledge its discovery while it was still in space.
Dozens of sightings have been reported to the American Meteorite Society, and scientists alerted to the Scout’s prediction were able to photograph the asteroid’s entry into the atmosphere. Videos of the fireball collected by the public have also been posted online. NASA’s Meteorite Falls website also reported a weather radar detection of fireball fragments falling as meteors at the expected time over Lake Ontario. Smaller meteorites can be found east of Grimsby while larger ones may be found near McNab.
The first asteroid detected and tracked before hitting Earth was 2008 TC3, which entered the atmosphere over Sudan and exploded in October 2008. That 13-foot-wide (4-meter size) asteroid scattered hundreds of small meteorites over the Earth’s surface. Nubian desert. Earlier this year, asteroid 2022 EB5 entered the atmosphere over the Norwegian Sea after Scout accurately predicted its location, becoming the fifth object to be detected before impact. As surveys become more sophisticated and sensitive, more of these harmless objects are caught before they enter the atmosphere, providing real exercises for NASA’s planetary defense program.
the quote: NASA Program Predicts Small Asteroid Impact Over Ontario, Canada (2022, November 23) Retrieved November 23, 2022 from https://phys.org/news/2022-11-nasa-impact-small-asteroid-ontario.html
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