When astronauts return to the Moon for the first time since the Apollo Era, they will be relying on a number of mission elements to get them there and back safely. This includes the Space Launch System (SLS) and Orionspacecraft that will launch a crew of four and carry them to the Moon. But until recently, the question of how they will get to and from the surface remained unresolved, as there were a few options.
Apollo 11 was the first mission to land people on the lunar surface. But Apollo relied on a lot of predecessor missions to lay the groundwork for the successful mission to the Moon. One of them was Apollo 10, the fourth crewed mission in the Apollo program.
Apollo 10 was an almost complete mission that including everything that Apollo 11 had, except for an actual landing on the Moon. It was a dress rehearsal, and was the second Apollo mission to orbit the Moon. It even had an Apollo Lunar Module that was flown to within 15 km of the lunar surface. But that module never landed, and eventually, after it rendezvoused with the command module and the crew disembarked, it was sent into orbit around the Sun.