Why is a NASA spacecraft crashing into an Asteroid?

This illustration made available by Johns Hopkins APL and NASA depicts NASA's DART probe, foreground right, and Italian Space Agency's LICIACube, bottom right, at the Didymos system before impact with the asteroid Dimorphos, left/AP

WASHINGTON: In the first-of-its kind, save-the-world experiment, NASA is about to clobber a small, harmless asteroid millions of miles away.