A small asteroid about 3 feet (1 meter) in size disintegrated harmlessly over Germany on Sunday, Jan. 21, at 1:32 a.m. local time (CET). But this event was not a complete surprise: NASA’s Scout system had predicted the impact location and time with remarkable accuracy, using only a few observations from a single observatory.
Scout is an impact hazard assessment system that monitors data on potential asteroid discoveries and calculates their possible trajectories and chances of impacting Earth. Scout was developed and is operated by the Center for Near Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory in Southern California. CNEOS calculates the orbit of every known near-Earth object (NEO) to provide assessments of potential impact hazards for the Planetary Defense Coordination Office (PDCO) at NASA Headquarters in Washington.
Scout automatically fetches the new data from the Minor Planet Center’s Near-Earth Object Confirmation Page, where astronomers report their observations of newly detected small celestial bodies. Scout then deduces the object’s orbit and impact probability, and alerts CNEOS and PDCO if an impact is possible. Scout also flags the object on its webpage to notify the near-Earth object observing community, so that more observations can be made to refine the orbit and impact prediction.
How Scout Predicted the Impact of 2024 BX1
The asteroid that impacted over Germany was later designated 2024 BX1. It was first observed less than three hours before its impact by Krisztián Sárneczky at Piszkéstető Mountain Station of the Konkoly Observatory near Budapest, Hungary. These early observations were reported to the Minor Planet Center and automatically posted on the Near-Earth Object Confirmation Page.
Scout fetched the new data from that page and identified that an impact was possible and that additional observations were urgently needed. With only three observations over 27 minutes from one observatory, Scout initially identified the possible impact locations, which extended from western Greenland to off the coast of Norway.
As more observatories tracked the asteroid, the calculations of its trajectory and impact location became more precise. Scout determined that 2024 BX1 would enter the atmosphere southwest of Jan Mayen, a Norwegian island nearly 300 miles (470 kilometers) off the east coast of Greenland and northeast of Iceland. Scout predicted the impact time and site within 1 second and about 330 feet (100 meters) of the actual event.
The asteroid’s impact produced a bright fireball, or bolide, which was seen from as far away as the Czech Republic and may have scattered small meteorites on the ground at the impact site. The impact was also confirmed by infrasound detectors, which measure low-frequency sound waves in the atmosphere.
Why Scout Is Important for Planetary Defense
This is the eighth time in history that a small Earth-bound asteroid has been detected while still in space, before entering and disintegrating in our atmosphere. The previous seven cases were 2008 TC3, 2014 AA, 2018 LA, 2019 MO, 2019 QY4, 2020 QG, and 2022 EB5. Scout played a role in predicting the impact of the last four of these asteroids.
While NASA reports on near-Earth objects of all sizes, the agency has been tasked by Congress with detecting and tracking NEOs 140 meters in size and larger that could cause significant damage on the ground if they should impact our planet. Those objects can be spotted much further in advance than small ones like 2024 BX1.
Tiny asteroids like this one impact our planet from time to time. They pose no hazard to life on Earth but can provide a useful demonstration of NASA’s planetary defense capabilities such as Scout’s rapid-response trajectory computation and impact alerts. Scout also helps astronomers to collect more data on these small objects, which can improve our understanding of their physical properties and origin.