The fear of space cafard must be somewhat similar to that of
seasickness every new sailor had back in ancient days when man sailed
the oceans of Terra. He never knew until he made his first voyage if he
was going to be susceptible; and, if he turned out to be, it meant the
sea wasn't for him.
* * * * *
Of course, space cafard goes tragically further. A new man usually
succumbs his first few hours in space, if he is going to get it at
all. He probably makes it to the next planet, sometimes not; sometimes
he goes incurably mad, right off the bat. But even if he does make
it, wild horses could never get him on another rocketship. He becomes
a halftripper, marooned on an alien world. Usually, although I have
known of several exceptions, if you don't get it on your first trip, it
seldom bothers you; you're immune for the rest of your life.