How would the earth stop a killer asteroid? You’ve seen the sci fi solutions…send a team of miners to plant an atomic bomb to blow it up! In reality, astrophysicists are studying what we might do if confronted with the case of an asteroid headed in our direction. Key to solving this sort of problem is identifying the asteroid years in advance. If detected today, for example, the earth would need seven years to be able to affect the trajectory of the asteroid in time to miss earth. Two kinds of missions are suggested, the first would be to explore the asteroid and to determine if it did in fact present a threat, and the second would be a mission to either slow down or accelerate the asteroid so that it would miss the point of collision. Any launch of vehicles from earth would need to be sent years in advance to have any effect of a rock hurtling to earth.
See and read more at: https://www.space.com/asteroid-threat-simulation-nasa-deflection-idea.html