NASA is developing the first-ever mission that will work as a planetary defence mechanism against potential cosmic body impacts in the future.
The mission, The Double Asteroid Redirection Test (DART), is being designed, built and managed by the John Hopkins Applied Physics Laboratory.
The mission has moved from concept development to preliminary design phase, following NASA’s approval on 23 June 2017.
It is the first-ever design that will have the capability of deflecting a near-Earth asteroid.
It would demonstrate the kinetic impactor technique by knocking the hazardous object into a different flight path that would not threaten the planetary defence.
The approval by NASA advances the project towards a historic test with a non-threatening small asteroid.
The target for DART would be an asteroid that will have a distant approach to Earth in October 2022 and then again in 2024.
The asteroid called Didymos (Greek for twin) consists of two bodies: Didymos A, which is about 780 metres in size, and Didymos B, which is a smaller asteroid about 160 metres in size.
DART would impact only smaller of the two bodies, Didymos B, the composition of which is unknown.
The size is typical of asteroids that could potentially create regional effects should they impact Earth.
After launch, DART would fly to Didymos and use an APL- developed onboard autonomous targeting system to aim itself at Didymos B.
The spacecraft is expected to strike the smaller body at a speed that would be about nine times faster than a bullet, around six kilometres per second.
Earth-based observatories would be able to see the impact and the resulting change in the orbit of Didymos B around Didymos A, allowing scientists to better determine the capabilities of the kinetic impact as an asteroid mitigation strategy.
The kinetic impact technique works by changing the speed of a threatening asteroid by a small fraction of its total velocity.
By doing it well before the predicted impact, the small nudge will add up over time to a big shift of the asteroid’s path away from Earth.
DART is a critical step in demonstrating we can protect our planet from a future asteroid impact. As we don’t know that much about their internal structure or composition, this experiment needs to be performed on a real asteroid.