[freshair]

> "A space elevator makes no sense on the moon. First of all the orbit is unstable and you would need constant station keeping."

In a typical space elevator, the counterweight end of a space elevator is not in orbit. The center of mass of a space elevator would be above geostationary orbit, so the counterweight would be moving substantially faster than orbital speed at its altitude. A space elevator is held taut by centrifugal "force".

For the Moon it would work a bit different; the Moon doesn't spin fast enough for a purely centrifugal elevator. Instead the elevator would pass through one of the Lagrange points, in effect being held taut between the gravitational pulls of Earth and the Moon.

The Lagrange points aren't stable orbits either, but technically the space elevator would be going through a Lagrange point, not sitting inside that region in orbit. I am not sure how much station keeping would be required. You might still be right overall here.

[nickik]

The question is what the advantage is. If you are launch bulk materials, a railgun will be cheaper.

And for human launch a SSTO reusable lander should be fine.

[freshair]

Perhaps the niche for a space elevator is bulk passenger transit. An elevator could perhaps ferry more people than a reusable lander, while not turning them into goo as the g-forces of a railgun might.