1894-1989 1906-1969 1912-1977 astronaut astronautes astronautics astronauts bemannteraumfahrt biografie biographie biographies biography duitsers encyclopedias encyclopédies germany geschichte hermann histoire history influenceehricke influenceley influenceoberth influencevonbraun kraffta mannedspaceflight propulsion rocketry rockets scientists spaceflight spaceflighttothemoon unitedstates volspatialhabité wernher willy