This Sunday, a car-sized asteroid slammed into Earth less than 3,000 kilometers away. Astronomers didn't notice its existence until six hours later.
This Sunday, a large rock 5.5 meters wide by two meters long approached within 2950 kilometers of Earth, spinning at more than 44,000 km/h over the southern hemisphere. Now named 2020 HQ, the object was not detected until six hours later by the Palomar Observatory in California. "We didn't see it coming “, emphasizes Paul Chodas, director of NASA’s Center for Near Earth Object Studies.
According to this same researcher, this flyby is "closest ever recorded “, if we obviously exclude the few known asteroids that have actually impacted our planet.
Note that last May the object baptized 2020 JJ, of a size comparable to that of a small van, had also passed incognito only 13,400 kilometers from our planet.
Either way, these two objects posed no danger to humanity anyway. In the event of a closer "flirt", the atmosphere of our planet would indeed have in charge of disintegrating them , triggering an airburst equivalent to the explosion of a few tens of kilotons of TNT about four kilometers above the ground.
However, this new intrusion into the near-Earth environment reminds us how important it is to constantly monitor the skies. Since 2005, NASA has focused more on rocks more than 140 meters in diameter . In May 2019, the agency said it had unearthed less than half of an estimated 25,000 objects that size or larger in the Solar System.
This threat is taken so seriously that ESA and NASA have joined forces on the DART (Double Asteroid Redirection Test) mission, which aims to deflect the trajectory of an asteroid in 2022. The two agencies have already chosen their target:(65,803) Didymos, a binary asteroid discovered in 1996.
Despite everything, some smaller ones could also do a lot of damage. In July 2019, an asteroid 130 meters in particular passed within less than 72,400 kilometers from our planet (less than 20% of the Earth-Moon distance). And astronomers had only detected its presence days before its closest approach. In the event of an impact, such a rock could have killed tens of thousands of people .
As of next year, researchers will nevertheless be able to count on the support of the Vera C. Rubin Observatory. This instrument will allow the discovery of thousands of new asteroids, some of which could pose a threat to our planet.
