If we slam an impactor into an asteroid in exactly the wrong spot, the space rock may pass through a "gravitational keyhole" that brings it to Earth.

Can we safely deflect a killer asteroid without making it worse? Only if we avoid the gravitational 'keyhole,' scientists say

Source: space
Source Link: https://www.space.com/astronomy/asteroids/attempting-to-deflect-a-potentially-hazardous-asteroid-could-accidentally-put-it-on-a-collision-course-with-earth