The European Space Agency (ESA) is working on an early warning system for dangerous, hard-to-see asteroids.
Photos from open sources / The concept of the NEOMIR orbital observatory / ESA
The mission to study near-Earth objects is called NEOMIR. The spacecraft will orbit between the Earth and the Sun at the L1 Lagrange point, finding space rocks that are lost in the Sun’s bright light.
Usually, astronomers can detect asteroids by the sunlight they reflect. The proposed NEOMIR mission will be able to find asteroids 20 meters or larger that are not visible from Earth and are moving towards us from the direction of the Sun. This threatens with inevitable collisions with the Earth.
The spacecraft will use a 0.5-meter telescope with a large, corrected focal plane that allows it to see objects in infrared light.
The ESA says NEOMIR will monitor a closed ring around the Sun, a region that cannot be observed with telescopes on Earth due to the Sun’s dazzling rays. By making observations in the infrared part of the light spectrum, NEOMIR will detect the heat emitted by the asteroids themselves, which is not drowned out by sunlight.
In addition, this particular range of thermal emissions is absorbed by the Earth’s atmosphere – another reason why a telescope on Earth is not suitable for such missions.
It is assumed that asteroids 20 meters or larger heading towards Earth will be able to detect NEOMIR at least three weeks before approaching. In the worst case scenario, in which an asteroid is seen passing close to the spacecraft, we will receive at least three days’ warning of the asteroid moving from L1 to Earth as quickly as possible.
Currently, NEOMIR is at the initial stage of preparation. If all goes well, it will launch in 2030 on an Ariane 6-2 rocket.
An asteroid similar to the Chelyabinsk meteorite that caused an explosion in the Earth’s atmosphere could detect NEOMIR. The emission from this meteorite, or the direction of the source, was close to the Sun, so it passed unnoticed by other observatories. However, its size is such that NEOMIR can easily detect it. This space rock was approximately 18 meters in diameter and weighed 9,100 tons. The shockwave caused by the explosion blew out windows and damaged buildings, injuring nearly 1,500 people. Across the region, about 7,200 buildings in six cities were damaged.
Larger space rocks can cause even more damage and destruction when they hit the Earth. However, their estimated population in the solar system is small, and it is believed that more than 90% of them have been discovered. No known asteroid poses a collision hazard. Only a tiny fraction of asteroids less than 10 meters in diameter have been detected, but they would have disintegrated in the atmosphere without causing harm.
An initial study to assess the feasibility of the NEOMIR mission was carried out by the ESA Parallel Engineering Center in the Netherlands in 2021 and the project is currently being refined and the detector technologies and associated electronics for this new mission are in the development phase.