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A Universe to Explore
The Why of it All
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acceleration alien Apollo approach asteroids astronauts atmosphere attained beam become black hole body centre century civilization comet craft crew Daedalus decades direction distance Earth effect encounter escape velocity event horizon exhaust velocity exist exploration faster-than-light final velocity fly-by fuel fusion galactic Galaxy global gravitational field growth hibernation human hydrogen increase inhabitants intelligence interplanetary interstellar Ark interstellar travel journey Jupiter kilometres kind laser launch lunar Mars mass ratio massive material means metres million mission Moon moving NASA nuclear pulse rocket orbit parsecs payload perhaps period planetary system planets population possible probe problems Project Daedalus propellant propulsion Proxima Centauri radiation radius ramjet range reach reaction relative relativistic result satellite Shuttle society solar sail Solar System Space Ark space colony spacecraft spacetime species speed of light stars starship stellar surface temperature terrestrial thousand tion tonnes Universe vehicle Venus voyage zero