Robert A. Heinlein 
Green Hills of Earth 

Nine ships blasted off from Moon Base. Once in space, eight of them formed a globe around the smallest. They held this formation all the way to Earth. The small ship displayed the insignia of an admiral — yet there was no living thing of any sort in her. She was not even a passenger ship, but a drone, a robot ship intended for radioactive cargo. This trip she carried nothing but a lead coffin — and a Geiger counter that was never quiet.