That, and space elevators are feasible on the moon with todays technology which makes moving stuff into orbit much cheaper: https://en.wikipedia.org/wiki/Lunar_space_elevator

Using a lunar space elevator allows you to cheaply move materials from the moon into space and build huge interplanetary rockets without having to design your rocket around the rocket equation to get out of a gravity well.

In fact, the more I think about this, the more I think a lunar space elevator port is the key to exploring the solar system. You can build massive spaceships and refuel them without ever having to deal with the tyranny of the rocket equation.