NASA is about to smash a satellite into an asteroid. The asteroid, Dimorphos is a 'moon' of another, Didymos, in the Asteroid belt. The hope is to nudge it into a slightly different orbit in order to 'prove' that we could use the same process if a bigger asteroid ever threatens Earth.
So far, so good, but what of the unknowns?
Doing such a thing could upset the gravitational stability of that part of the asteroid belt and even further afield.
Some time ago I was reading about us mining asteroids and even taking them to the moon for mineral extraction. Two great concerns were that it was unknown what removing a very large asteroid, it would have to be large, a few km in diameter, to make it worthwhile, would do to the stability of gravitation in the belt. The other was about what would happen if one escaped en route to the Moon. These were blithely passed off as scare stories.
I sure hope that the scientist have got their maths right.