Been playing Rimworld again recently and one of the dlc's added in space ships and orbital stations.
And I found a mod that lets you fire missiles from orbit and lets you fill the missiles with toxic waste or napalm or dead bodies, any material really.
And I saw another mod that adds in poo and pee to the game as a material that you can store in tanks.
Pretty sure if I combine these I will be able to do orbital poo bombardments.