A devastating event in the worlds of
Mobile Suit Gundam.
Theory states that by using the 5
Lagrange Points around the
earth and
moon, one could place large colonies, capable of supporting millions of people in space. The points would then keep the colonies in stable positions. This is the basis behind the entire universe of Gundam.
These
colonies, capable of supporting upwards of 3 to 4 million people (possibly more), are huge. Containing full
atmospheres, they are often several miles long, and weigh in excess of several
billion metric tons easily.
One
military tactic used in the endless wars of the Gundam universes is attempting (and occasionally succeeding) to drop one or more of these colonies on earth. The resulting explosions would be greater than some of the largest nuclear detonations, leaving
craters visible from space.
This occurs most notably in
Gundam X, where the core of the story takes place on an earth devastated 15 years earlier by a
successful multiple colony drop. The resulting blasts created a (relatively) short
nuclear winter, killing most of the earth's population.
A colony drop was also the original intention of
Operation Meteor, the
codename of the mission the boys of
Gundam Wing were on. The colonies were going to be covertly (as covertly as that can be) dropped, then the Gundams would rush in and take control amid the panic.
Milliardo Peacecraft attempted to incite a smaller effect, after the original Operation Meteor had been foiled, by dropping a near colony-sized
spacecraft on the earth, but failed.
Another successful (maybe more) colony drop occurred in
0083, although I cannot say anything about it, as I have not seen this OAV series yet.