Asteroid spotted just two hours before impact

Almost overlooked: A few days ago, the earth was hit by an asteroid around two meters in size – the impact over the Arctic Ocean had no consequences. What is special, however, is that the chunk was only discovered two hours earlier. It is also only the fifth asteroid to be noticed before entering the atmosphere. The reason for this is the low brightness of such small celestial objects, which makes them almost invisible for the usual surveillance systems.

Impact craters, meteorite finds and events such as the Tunguska explosion are evidence that our earth is under cosmic bombardment: Asteroids keep flying close to the earth or hitting it. While larger chunks are under astronomical observation and their orbits are usually well known, this is not the case for smaller objects. They are so faint that they are often discovered late or not at all. Even a 100 meter asteroid was overlooked – but luckily it didn’t hit.

2022 EB5
Photo of the asteroid 2022 EB5, recognizable as a bright streak of light, round 13 Minutes before its impact. © ESA

A small, fast point of light

All the more it is rarer that astronomers at 11. March 2022 have discovered a chunk less than two meters in size at least just before its impact. It is only the fifth asteroid ever to be “caught” before entering the atmosphere and the first impactor to be detected by a European astronomer, as reported by NASA and the European Space Agency ESA.

It was discovered by Krisztián Sárneczky from the Piszkéstető Observatory in Hungary , when he was on the evening of 11. March scanned the sky with a 60 centimeter telescope. Around 20: 24 clock of our time, he noticed a small, fast-moving point of light. After the spot had moved significantly in four consecutive exposures, it was clear that it was measuring a fast, close-up object—a near-Earth asteroid.

Alarm chain starts

Already 14 Minutes later, the astronomer reported the new object to NASA’s Minor Planet Center, which alerted other astronomers and observatories. At the same time, NASA’s automatic “Scout” risk assessment system calculated the trajectory of the 2022 EB5-christened object based on the data submitted. “Scout initially only had 13 observation data on 40 minutes when he identified the object as an impactor,’” explains Davide Farnocchia of NASA’s Jet Propulsion Laboratory.

Only about an hour after the chunk, estimated to be two meters in size, was discovered, the Near-Earth Object Coordination Center (NEOCC) of the European Space Agency ESA and the Planetary Defense Coordination Office of NASA informed. At this point, calculations were already predicting that the asteroid would arrive just an hour later, between 21 : 20 clock and 16: 25 Clock , would impact in the Arctic Ocean.

Impact over the Arctic Ocean

This is how it happened: At 21: 24 o’clock the asteroid occurred around 140 kilometers north of the island of Jan Mayen – less than two hours after its discovery. The fireball could not be observed in this deserted area. But the worldwide network of infrasound sensors registered the shock. The energy released during the impact was roughly equivalent to an earthquake with a magnitude of 4.0. Astronomers estimate that the Earth is hit by chunks of this size about ten times a year – but these asteroids are usually only discovered when they impact.

“Small asteroids we 2022 EB5 are numerous and strike the Earth’s atmosphere relatively frequently,” said Paul Chodas, director of NASA’s Center for Near Earth Object Studies (CNEOS). “But because they are very faint up to a few hours before their impact, they are rarely discovered in space.” In addition, a surveillance telescope must have the right part of the sky in view at the right time.

New telescopes are supposed to improve surveillance

At least: The asteroids that are bigger and can cause serious damage are usually detected earlier. However, astronomers are working to further improve the monitoring of near-Earth objects. The Flyeye telescope, which is currently being built on Monte Mufara in Italy, should make a contribution to this in the future. Its optics work in a similar way to the compound eyes of an insect, in that they produce images from 16 partial images

“The extremely large field of view of these new telescopes will allow us to survey large areas of the sky in just one night,” explains Detlef Koschny, head of the Department of Planetary Defence at ESA. “This reduces the risk of missing a potentially significant object.”

Source: NASA Jet Propulsion Laboratory, European Space Agency (ESA)

14. March 2022

– Nadja Podbregar

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