 According to Ron, what motivated him and Val to join the Geigs?
We knew the pay was poor, but we had felt it a sort of obligation, something we could do as individuals to keep the industries of radioactives-starved Earth going. And that started the chain of events that led Val and me to end up as a madman's prisoners, on Mars. It's a stopgap effort, just to keep things moving until Project Sea-Dredge starts functioning. Enter the Geig Corps: volunteers out on the face of Mars, combing for its uranium deposits. For a puzzled moment I thought it was our Dome, the settlement where all of UranCo's Geig Corps were located, but another look told me that this was actually quite near us and fairly small.
 desire to maintain their present way of life
 desire to maintain their present way of life  monetary compensation  opportunity for a new life on Mars  heroic reputational status upon returning to Earth