They’re mounted on the boosters (three on each), on or in the orbiter (five), and on the tank (one). Space Shuttle Main Engines ... and the other into the payload bay. In the early 1990s ...

In other ways, though, the X-37 will be picking up where another U.S. spaceplane, NASA's space shuttle ... change out the payload bay quickly, and put into a different orbit, and do all that ...