The entire Apollo 11 mission to the moon took just eight days. If we ever want to build permanent bases on the moon, or perhaps even Mars or beyond, then future astronauts will have to spend many more days, months and maybe even years in space without a constant lifeline to Earth. The question is how would they get hold of everything they needed. Using rockets to send all the equipment and supplies for building and maintaining long-term settlements on the moon would be hugely expensive.