Presumably you meant WITHOUT sex. However, there's no reason to expect that they would have to abstain during the trip.
I'd love to see it happen, though. [ETA: the trip, not the sex. Necessarily.] Not sure whether they can pull it off. I would imagine one big problem will be, yes I'll say it, radiation. Maybe that's why they're looking for "mature" folks who won't be around long enough for the extra exposure to matter.
~cough~
And yes - interesting Freudian slip there by me, I was having wistful and fond recollections of such things
The radiation issue has been mentioned in some reports, and no doubt quotes will be flung around by the Apollo denier community as they fail to distinguish between 18 months and a couple of weeks.
I think this is a marvellous thing, but it will be 9 months of not an awful lot happening, followed by a brief period of "HEY WOW!!", then another 9 months of not an awful lot happening. The periods of not an awful lot happening will be filled with conspiracy theory nonsense about the people they send being somewhere in a basement on Earth and the Mars footage will be all CGI
I think it's a shame that they won't be going to the surface. I can see why, as it makes the cost of the whole thing affordable to the average billionaire space industry backer, but I think it will be very psychologically difficult. You could perhaps cope with the privations of the long journey if you knew that you were getting out at the end for a walk, but to just orbit a few times and head straight back? There will be people arguing that you might as well send monkeys.
I suppose they would get valuable information about human biology and psychology in preparation for a longer surface bound mission, and there is something in our nature that makes eyewitness testimony more valuable and interesting than the view from a camera alone. I am interested and excited to see how this turns out, and look forward to private industry looking at the moon with more seriously in the near future too.