You can get to the moon base!! just buy the green meteorite thing at the coffee shop. wait until it arrives in the mail in your current house. once you have the meteor in your pockets, go to the phone booth in Sim Quarter. go in and 'Phone Home!' youll be at moon base zeta!! just go back to the phone booth to return to Sim Quarter.youll always have access to the base as long as the meteor is in your 'Pockets'
(p.s. there is a xizzle bead in the leftmost room of the base)