As far as it goes there are no rules; but, only as far as it goes. I tell you this in all confidence, but, if it should go any further… well, let me leave that unspoken.
Between Earth and Mars there are only eighty-four hours of travel, or is that eighty-four days? I always get the two mixed up. Without easy access to a timetable I’m not that sure when the next shuttle is due, or when it would be arriving at the Red Planet. There’s also the problem that there might be a need to change shuttles along the way.