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How can a kinetic-impact spacecraft help deflect an asteroid on a collision course with Earth?

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The Chicxulub asteroid — Earth impact hazard An artist's rendering of the impact of a near-Earth object 66 million years ago in what is today the Caribbean region. Many scientists think that the collision of a large asteroid or comet nucleus with Earth triggered the mass extinction of dinosaurs and many other species near the end of the Cretaceous Period.

A kinetic-impact spacecraft is a strategy used in planetary defense to mitigate the threat of an asteroid on a collision course with Earth. This method involves sending a nonexplosive projectile to strike the object at high speed, which alters its orbit enough to avoid an impact.12

The effectiveness of this approach was demonstrated by the Double Asteroid Redirection Test (DART) mission in 2022. When the DART spacecraft collided with the asteroid Dimorphos, the impact did more than just transfer momentum through the collision itself. The force of the impact ejected tons of material from the asteroid, which further enhanced the change in the asteroid's orbital period. This process successfully altered the orbit of Dimorphos significantly more than scientists had originally anticipated, proving that kinetic impact is a viable strategy for redirecting potentially hazardous objects.12