[Manned space flight--man, the weakest link in this endeavor?].
D018504:Ecological Systems, Closed; D005118:Extraterrestrial Environment; D006801:Humans; D013026:Space Flight; D013997:Time Factors; D014893:Weightlessness
Bemannte Raumfahrt--der Mensch, schwächstes Glied dieses Vorhabens.