NASA considers all space objects flying from Earth at a distance of 193 million km and closer as "near-Earth", and anybody flying closer to 7.5 million km from Earth as "potentially dangerous". After such bodies are entered into a special register, they are monitored to control possible changes in the predicted trajectories, as a result of which a threat to the Earth may arise. Although no particular threat is expected from the recently discovered 2022 RM4, a body with a possible diameter of 740 m, the brightness of which will increase to 14.3 mag, will be clearly visible in the sky even with "home" telescopes, writes 3Dnews.ru.
Today, NASA tracks the position and orbits of approximately 28 thousand asteroids, identifying them using the so-called Asteroid Terrestrial-impact Last Alert System (ATLAS) - a chain of four telescopes capable of fully scanning the entire starry sky every 24 hours. Since the ATLAS system started working in 2017, it has identified more than 700 near-Earth asteroids and 66 comets, and two of them - 2019 MO and 2018 LA actually hit the earth - near Puerto Rico and South Africa, respectively, but their sizes were so small that nothing catastrophic happened.
According to the estimates of the aerospace agency, collisions with bodies of "apocalyptic" sizes are not expected at least in the next 100 years, but, according to scientists, such data do not give a reason to relax. Although most near-Earth objects are unlikely to be able to end the Earth's civilization, there are quite a few catastrophic collisions in the history of the planet.
So, in March 2021, a meteor the size of a bowling ball exploded in the atmosphere over the state of Vermont in the USA (200 kg in TNT equivalent), and in 2013 a fairly powerful explosion occurred over Chelyabinsk, according to some estimates, its power reached 400-500 kilotons or 26-33 times more than that of a bomb dropped to Hiroshima. During the explosion over Chelyabinsk, buildings were damaged, many windows were knocked out, and about 1,500 people were injured of varying severity.
Space agencies are already working on the creation of planetary protection. So, at the end of last month, the DART probe managed to change the asteroid's orbit for the first time in history - the target was a Dimorph, which, fortunately, did not threaten the Earth. China also announced the beginning of the preparation of a mission to change the orbit of one of the celestial bodies. We are talking about the asteroid Bennu, which should fly at a distance of 7.4 million km from Earth's orbit between 2175 and 2199, and Chinese scientists hope to prevent a potentially dangerous collision.
