There are only about sixty days left before the American space probe DART (Double Asteroid Redirection Test) reaches its goal. Launched in November 2021 from Vandenberg Base in California, the half-ton cube-shaped machine flies through space at a speed of 24,000 km/h. And it will collide with the asteroid Dimorphos on September 26, 2022, which will then be 11 million kilometers from Earth.
This asteroid, approximately 160 meters wide, orbits an 800-meter-diameter rocky object called Didymos in just 11 hours. And it is by measuring the post-collision change in the orbital period of Dimorphos (reduced by about 10% according to estimates) that the DART mission will test the impact of a kinetic impactor on an asteroid’s course… a method that could deflect a near-Earth cruiser heading straight for our planet, and thus thus avoiding a regional cataclysm if such a meteor were once identified.
A diagram representing the binary asteroid targeted by the DART mission. 1 credit
Mission in two stages
The results of the collision with Dimorphos (orbital period modification, crater formation, debris ejection, etc.) will be analyzed by the Italian nanosatellite LICIACube (Light Italian CubeSat for Imaging of Asteroids) aboard DART and catapulted ten days before the collision. And in 2024, the European probe HERA will fly to a binary asteroid to enter orbit, map the surface of Dimorphos and collect extremely accurate information thanks to a set of instruments (cameras, radar, thermal imager, gravimeter, altimeter, etc.).
China intends to play a role
But in a few years, the United States and Europe will no longer be the only space powers working on planetary defense and experimenting with this type of technology. Because China intends to play its part and is also developing an asteroid deflection mission. Announced for the first time last April, the project was detailed during a conference hosted by Chinese engineer Long Lehao, who piloted the Long March launch vehicle design as well as China’s lunar exploration program. The mission, developed by the China Space Administration, will be launched in 2026 using a Long March 3B launch vehicle.
New details on China’s asteroid deflection mission: 2026 launch of a Long March 3B rocket targeting the Earth-crossing near-Earth asteroid 2020 PN1 (~40 m in diameter). According to a slide from a lecture by Long March designer Long Lehao, it will combine an orbiter and an impactor. pic.twitter.com/GRWpRDCbgy
— Andrew Jones (@AJ_FI) July 12, 2022
Engineer Long Lehao presents the Chinese mission concept.
Smaller target than Dimorphos
As well as the DART and HERA programs, united under the AIDA consortium (Estimation of collision and deflection of an asteroid), it will test the projectile’s ability to deflect a threatening celestial object. But the Chinese mission will include both an impactor launched at full speed towards the asteroid and an orbiter that will study the aftermath of the impact. The target will also be smaller than Dimorphos. This is asteroid 2020 PN1 with a diameter of about 40 meters. Discovered two years ago by the Haleakala observatory in Hawaii, it is part of an Aten-type asteroid and will be 19 million kilometers from Earth in 2026.
These facilities would destroy a city like Lyon
Only NEOs with a width of more than a kilometer can cause a planetary cataclysm, and with a diameter of more than 140 meters, such as Dimorphos, a regional catastrophe. Therefore, 2020 PN1 is below this threshold. However, hitting the Earth, asteroids of this size can cause significant damage, for example, destroying a city like Lyon. They are also much more numerous and harder to spot than asteroids like Dimorphos. Thus, the Chinese mission will provide valuable information to try to protect itself from such threats.
Due to their small size, the vast majority of asteroids around 25 meters wide have yet to be identified. Credit: DART/NASA/NPS