In 1985, Rockwell International considered the possibility that there might be profit in clustering the External Tank from the Space Shuttle in Earth orbit. There the tanks could be filled with propellant to serve as orbital “gas stations,” or rebuilt into space habitats or other structures, or simple reprocessed for the raw structural materials. In order to do this the Shuttle would have to shed a noticeable fraction of total payload. Something not given a whole lot of thought was what to do about the insulating foam applied to the tanks; ultraviolet sunlight, thermal cycling and a harsh vacuum would cause the foam to break down ans turn each orbiting tank into a little comet, the nucleus of a cloud of foam bits.
Still, it would have been nice if the tanks had been used rather than simply dumped into the Indian Ocean.
