The European Space Agency (ESA) has announced that it is building a new space telescope with the aim of locating asteroids making their way towards Earth – from the direction of the blinding Sun. According to the plan, the Near-Earth Object Mission in the InfraRed telescope, or NEOMIR, will be launched in 2030 to the Lagrange 1 point on the Earth-Sun axis, and from there it will locate dangerous objects that cannot be seen today due to the blinding light of the Sun. NEOMIR will complement the capabilities of NASA’s space telescope, NEO Surveyor, which will be launched in 2026 and will specialize in detecting asteroids smaller than 140 meters in diameter.
The lessons from the explosion in Chelyabinsk
Humanity’s ability to detect dangerous objects has improved dramatically in recent years. Observers on the ground such as the Asteroid Terrestrial-impact Last Alert System today scan 100% of the night sky every 24 hours in search of near-Earth objects (NEO’s) – asteroids and comets that may make their way to us. On February 12 of this year, for example, an alert was received about the impact of a small asteroid, less than one meter in diameter – and indeed seven hours later it exploded over the English Channel. The asteroid, 2023 CX1, was the seventh asteroid in history to be discovered before hitting Earth.
However, asteroid observers on the ground are unable to detect asteroids coming from the direction of the sun, since they are very dim compared to the blinding light, and the fear is of a large object that will suddenly emerge from the sky in daylight. Thus, for example, on February 15, 2013, an asteroid with a diameter of about 20 meters hit the Earth. The meteor exploded in the air over Chelyabinsk in Russia, and the force of the impact injured about 1,500 people and caused damage to about 3,000 buildings. The inhabitants had no advance warning, as the asteroid came from the direction of the Sun.
The NEOMIR mission aims to close this loophole. The telescope is expected to be launched on top of an Ariane 6 to the Lagrange point 1. Lagrange points are points of gravitational stability between any two bodies, where the Lagrange point 1 is about 1.5 million km from the Earth, at the point of gravitational balance between the Earth and the Sun.
From there, NEOMIR is expected to detect any object over 20 meters in diameter orbiting the Sun, and provide us with at least a three-week warning. In the extreme case that NEOMIR detects an asteroid that is not in front of it – that is, in the direction of the Sun – but on its sides – that is, an asteroid that will pass by – the warning will be for at least three days, since this is the fastest time that an asteroid can reach from Lagrange Point 1 to the Earth.
NEOMIR will be equipped with a half-meter mirror with an extremely wide focal point, and it will be a dedicated telescope for infrared photography at frequencies of 5-10 micrometers. Since it will shoot in the infrared, the telescope will actually look for the heat signatures of the objects, and will not be affected by the blinding light of the sun. Furthermore, these specific frequencies are absorbed by the atmosphere, so observers on the ground are unable to see these heat signatures.
NEOMIR will complement NASA’s field of view
“There are two reasons why we didn’t see the asteroid that exploded over Russia before it entered the atmosphere,” explains Dr. David Polishuk of the Weizmann Institute of Science. “First, the asteroid arrived during the day, and telescopes on the ground are unable to operate in daylight. And secondly, the asteroid came from the direction of the Sun, so its bright side was not the side facing us – meaning its brightness was very low. The NEOMIR space telescope will look out with the Sun behind it, so it will see the bright side of asteroids coming from the direction of the Sun. Another advantage of NEOMIR is the infrared observation. You have to understand that the sun heats asteroids that are relatively close to it, and when they heat up they emit infrared radiation. It is much easier to identify asteroids by heat signature than by light signature, since their light reflection is very low – some of them absorb up to 95% of the light, meaning they absorb it and heat up.”
According to Dr. Polishuk, the new space telescope is real news for the inhabitants of the planet. “The telescopes we have on the ground work at night. They steal a few degrees to the right and left at sunrise and sunset, but overall, out of a 360-degree sky fan, a telescope on the ground sees a little more than 180 degrees – a sky dome of half the Earth. What is it similar to? For the dead zones in the car, which the mirrors do not cover. A space telescope like NEOMIR will cover our dead zones, and after it is launched we can know for sure that an asteroid like the one that exploded in the sky of Russia will not surprise us again.”
The European Space Agency’s new space telescope is designed to complement the capabilities of NASA’s NEO Surveyor space telescope, which will be launched in 2026. NASA’s space telescope will operate similarly to its European counterpart, except that it is designed to detect asteroids larger than 140 meters in diameter. The 140 meter line indicated that asteroids of this size or larger could wreak havoc on a regional, continental and even global scale.