Analysis: Colony Drop
Note that in real life, the colony and moon version of this is very, very difficult. It's nearly as hard to take something out of orbit as it is to put it in in the first place, as all the momentum must be shed. The energy necessary to do this is actually more than will be released in the collision. Note, most of the force would come from Aerobraking in the atmosphere, so not all that hard for something in low earth orbit where "stationkeeping" burns are required to to keep the object in orbit.