NASA has warned that there are approximately 15,000 near-Earth asteroids that have not yet been detected, even though they have enormous destructive capabilities that could reach the level of wiping out entire cities if they collide with the planet.
These objects are known as “city destroyers,” due to the widespread destruction or tsunami waves they can cause if they fall into the oceans.
What are “city destroyers”?
Kelly Fast, responsible for the planetary defense file at the agency, explained that these medium-sized asteroids are difficult to detect due to their relative small size compared to giant asteroids, but they carry enough impact energy to cause catastrophic effects.
It is estimated that the number of asteroids with a diameter of more than 140 meters is about 25 thousand objects, but scientists have so far been able to monitor only about 40% of them, which leaves a large gap in the space monitoring system.
The danger of these asteroids lies in the nature of their orbits, as many of them approach the Earth from the direction of the sun, which makes discovering them using optical telescopes very difficult, as these devices rely on reflected light, while objects coming from the direction of the sun remain hidden behind its glow.
To overcome this challenge, scientists are working to develop infrared monitoring techniques that can detect dark objects that do not reflect light efficiently.
It is expected that the launch of a new space telescope dedicated to monitoring asteroids in the coming years will contribute to filling this gap and improving early detection capabilities.
What is the effect of “city destroyers”?
Scientific estimates indicate that an asteroid collision with a diameter of about 140 meters could be equivalent in power to hundreds of nuclear weapons, highlighting the importance of strengthening early warning systems and defense planning.
The Dart mission experiment in 2022 demonstrated the possibility of actually changing the path of an asteroid, after it succeeded in modifying the orbit of a small moon belonging to an asteroid, which is an important step towards developing planetary protection methods.
Although the probability of a collision of this type occurring is statistically estimated to be once every 20,000 years, scientists stress the necessity of preparing for such scenarios, especially since the late discovery of any dangerous object may limit the time available to take effective defensive measures.
NASA is currently working, in cooperation with international partners, to develop advanced monitoring and simulation programs for collision scenarios, with the aim of enhancing global coordination and rapid response to any potential threat in the future, thus contributing to protecting the Earth and its inhabitants from the dangers of near space.
