I watched it a long time ago. Are you talking about the manga? I don't remember this at all. There were lots of people who spent extended periods in space, Nono in particular spent her whole life on the moon, which doesn't have a molten core, and thus nothing to deflect much of the harmful radiation from the sun, and she's still alive and kicking after 12 years. True, the dangers in the Von Braun would include more than radiation, but the anime left off being rather hopeful, I thought. Are you just pulling things out of your ass?