Welcome to the Disney Parks Moms Panel Dolores ~
I completely understand your plight. I too have been there, done that but I am never doing it again. While Mission: SPACE is truly incredible, the claustrophobic person living inside of me conquered my fears once but just can not bring myself to doing it again.
Being the good friend that I try to be, I waited in line with one of my friends. I was allowed to wait in line all the way until they actually counted Guests for spots to board for the mission. Guests who decided they wanted to withdraw from the mission were directed from that point to the
Mission: SPACE Advanced Training Lab. It is an interactive game area at the exit of the attraction. All Guests come through it after they complete their mission. It will keep you entertained while you wait on your son and he will also enjoy it once he has finished the ride.
Please feel free to visit us with all of your planning questions. It is our pleasure to assist you!
Wishing you minnie magical memories :-) Allison V.