If we can count on a clear path to the target world, and the target world
has an atmosphere, then why not mine the ore and shape it like a
parachute, balancing the majority of the weight around the rim, and making
sure to have lots of "vacuum pockets" in it. Then aim it at the world and
fire with the opening of the metal shoot being that the front of the
projectile. When it hits the atmo, it's shape could give it plenty of
drag and then it would land in the ocean and, due to all the vacuum
pockets, be buoyant enough that it will float and can be pick up at
leisure.
Of course, if we can't count on an uninterrupted path between the mining
facility and the world, I don't see any way that this could be done
without tacking on some course correction machinery.
> Nyotekundu Sourcebook.
>
> To stop it? Use the target planets gravity of course. Basically the
> accelerator is firing the ore into an orbit around the planet. Match speed
> and pick it up.