[woodman]

Stress can really put the zap on even those at their reproductive peak. It is a very common experience for men going through USMC bootcamp to not have a single erection in the 3 months they're there. Same story during combat operations. I fought in Fallujah for 7 months and I can tell you that sex was near the bottom of my list of concerns. Sure the number of opportunities were low, but even pornography held no interest. The tales of sex on deployment occur in very low stress environments: Navy ships and mega-bases, between personnel who don't see combat and have ice cream socials...

I imagine a Martian outpost would initially be pretty stressful. Once it becomes safe enough, and the stress levels decrease, sex won't be a mission-success/safety concern any longer. That isn't to say that there shouldn't be a plan in place, but it isn't as big a deal as folks make it out to be.