A closer look at the Falcon 9 rocket

Space X describes the Falcon 9 rocket as a "reusable, two-stage rocket" and the lower part of the rocket can be returned to Earth to be used again after launch. But other parts of the rocket are shed in space and remain there, stuck in orbit, unless they collide with another celestial body. SpaceX launched this specific Falcon 9 rocket as part of a US and Japanese mission to carry a pair of lunar landers and scientific equipment to the Moon last year. The upper stage of the rocket is a