In the early hours of Saturday, Nov. 19, the skies over southern Ontario, Canada, lit up as a tiny asteroid harmlessly streaked across the sky high in Earth’s atmosphere, broke up, and likely scattered small meteorites over the southern coastline of Lake Ontario. The fireball wasn’t a surprise. Roughly 1 meter (3 feet) wide, the asteroid was detected 3 ½ hours before impact, making this event the sixth time in history a small asteroid has been tracked in space before impacting Earth’s atmosphere.
NASA is tasked with the detection and tracking of much larger near-Earth objects that could survive passage through Earth’s atmosphere and cause damage on the ground, but those objects can also be detected much further in advance than small ones like the asteroid that disintegrated over southern Ontario. Such small asteroids are not a hazard to Earth, but they can be a useful test for NASA’s planetary defense capabilities for discovery, tracking, orbit determination, and impact prediction.
“The planetary defense community really demonstrated their skill and readiness with their response to this short-warning event,” said Kelly Fast, Near-Earth Object Observations program manager for the Planetary Defense Coordination Office (PDCO) at NASA Headquarters in Washington. “Such harmless impacts become spontaneous real-world exercises and give us confidence that NASA’s planetary defense systems are capable of informing the response to the potential for a serious impact by a larger object.”
The asteroid was discovered by the NASA-funded Catalina Sky Survey in Tucson, Arizona, on the evening of Nov.18 during routine search operations for near-Earth objects. The observations were quickly reported to the Minor Planet Center (MPC) – the internationally recognized clearinghouse for the position measurements of small celestial bodies – and the data was then automatically posted to the Near-Earth Object Confirmation Page.
NASA’s Scout impact hazard assessment system, which is maintained by the Center for Near Earth Object Studies (CNEOS) at the agency’s Jet Propulsion Laboratory in Southern California, automatically fetched the new data from that page and began calculating the object’s possible trajectory and chances of impact . CNEOS calculates every known near-Earth asteroid orbit to provide assessments of potential impact hazards in support of NASA’s PDCO.