After gathering precise measurements of the rotation and velocity of an incoming asteroid, two large clouds of white paintballs would be shot at the asteroid from a nearby spaceship.

FORBES: An Earth-Killing Asteroid Could Be Deflected With Paintballs

This involves pitching the machine's nose up to reduce its forward velocity and increase the speed of rotation of the blades (and thus the amount of lift they provide) to soften the landing.

ECONOMIST: Monitor