Ever wonder how Aperture managed to harvest so many moon rocks?

This group's goal is to make a Portal 2 singleplayer map that takes place on the moon, spanning over several maps. The scale of the project is up in the air at the moment, and any ideas or concept would be useful.
Someone on an Aperture Science moon base needs to be rescued. The party escort bot (the player) he requested arrives on the outskirts of the base and must work its way across the moon surface and into the base. The escort bot will go through a series of testing tracks in order to save him.

Project Notes (Google Plus)[docs.google.com]
Super Ninja Fat's Concept Art