Asteroid strikes are difficult to anticipate as to when and where.

Not really, the people in that business have tracked a number
of large asteroids, one of which passed between the moon and earth.
They measure their orbit and project it onwards to see if it will hit earth.
They may find that it will hiy earth in 150 years time.
One NASA project was sent to land on an asteroid to sample it to see
what its composition was. It had a second purpose to see if they
could land on an asteroid and give it a push into a different orbit.
Knowing the mas of the asteroid they would know how powerful a rocket
or how many would be needed to move it into a safe orbit.
Anyway that is where the technique is at present.