A big reason the Space Shuttle looks the way it does is a planned mission called Shuttle Reference Mission-3b. The plan was to capture and return a satellite from a polar orbit in less than 2 hours, a single orbit. It required a few rather difficult specification to the shuttle such as a large delta wing that then required a more robust heat shield. Plans for the mission were dropped before the shuttle flew probably because it was too ambitions but the changes lived on.
—David Foss