NASA is developing Double Asteroid Redirection Test (DART), the first-ever mission that will deflect a near-Earth asteroid.
The mission will help to test the systems that will allow mankind to protect the planet from potential cosmic body impacts in the future.
The DART will be built and managed by the John Hopkins Applied Physics Laboratory (APL). It will be NASA’s first mission to demonstrate kinetic impactor technique. The target for DART is an asteroid called Didymos that will have a distant approach to Earth in October 2022 and then again in 2024.
The asteroid Didymos (Greek word for twin) is an asteroid binary system that consists of two bodies: Didymos A (about 780 metres in size), and Didymos B (about 160 metres in size), smaller asteroid orbiting Didymos A. DART will impact only the smaller of the two bodies, Didymos B.
After launch, DART will fly to Didymos and use an APL- developed onboard autonomous targeting system to aim itself at Didymos B. The refrigerator-sized spacecraft will strike the smaller body at a speed about 6 km/s i.e. about nine times faster than a bullet.
Earth-based observatories will observe the impact and the resulting change in the orbit of Didymos B around Didymos A. It will allow scientists to better determine the capabilities of kinetic impact as an asteroid mitigation strategy.
Didymos asteroid system
The Didymos asteroid system has been closely studied since 2003. It has been classified as potentially hazardous asteroid. Its primary body is a rocky S-type object, with composition similar to that of many asteroids. The composition of its small companion, Didymos B is unknown, but its size is typical of asteroids that could potentially create regional effects should they impact Earth.
Kinetic impact technique
This technique involves sending one or more large, high-speed spacecraft into the path of an approaching near-earth object to shift its orbit to defend against future impact. It works by changing the speed of a threatening asteroid by a small fraction of its total velocity. This is done well before the predicted impact so that this small velocity adds up over time to a big shift of the asteroid’s path away from Earth.