Don't be silly. They're not coming back. They will colonize Mars and grow their crops there. Reproduce and have families. Build cities. it'll be some years before they can build the subway, ya' understand but all good things come to he who waits.
I agree. It’s a one way trip regardless of how it is sold to be. As long as they have many supplies and options to overcome unknowns they may survive a long time, possibly thrive there.