Now a refueled SS will head to the moon, where it will dock with the Orion capsule that is basically 1.5 times the size of the Apollo capsule. SS will dwarf Orion, like 20 times bigger. SS will take 4 people down to the moon. It will then bring them back to Orion where they will then return to the earth.
NASA picked Space X for this over some legacy space contractors. There were a lot of mad Congressmen and women. The thing is, everybody knows that SX can do the job for the whole mission. They can launch, land, and return the astronauts back to the earth, and since SS/SH is fully reusable they can do it for millions, not billions. Like literally billions of dollars cheaper. A lot of smart people think that NASA will only launch SLS ( senate launch system) once or twice.
