When you first think of the ideal candidates to make it through a gruelling 500+ day, 112 million km round trip to Mars, you don't exactly picture an old and crotchety married couple, but apparently that's just what's needed. The Mars Project wants a "tested" couple that could stand being so damn close to each other for over a year in a tiny box; I can kind of see their point.
The strength of the couples' bond will be severely tested, and the selection process will be quite gruelling, but the perfect couple will also be at least middle-aged. That's primarily to do with the fact that they're going to be bombarded with cosmic radiation, which will have less effect on the aged than the young and nubile.
The Mars500 project is looking to blast off in January 2018, because of the combined orbits of Mars and Earth put us in close-ish proximity at that point, although the round trip will still take over a year and a half. So, if you happen to be in your 40s or 50s and you and your better half fancy going to see Mars, maybe you should apply. Me, I'm happy with my feet firmly on Planet Earth until someone's proven you're not going to mutate into The Thing bathed in deep-space radiation. [BBC]