Colonization of Mars (for example) has a pretty obvious and clear obstacle: The enormous distance. The Moon is kinda "close". Are there any theoretical (or technological) obstacles that would prevent us from living on the Moon?
For example, would we be able to maintain a permanent life support system? It was successful in several space station projects, such as Mir and obviosuly the ISS, but the Moon is farther away - a life support system needs a constant supply, but bringing water, oxygen, and food would take some days, so immediate intervention is not possible, if something goes wrong.