20thcenturyamericanhistory aerospaceengineering astrogeology astronauticalengineering astronautics astronauts astronomicalstudies astronomy bigbangtheory boring comets designandconstruction drillingandboringmachinery equipmentandsupplies exploration flugkörper history juvenileliterature mars(planet) marsprobes microwaveanisotropyprobe(spacecraft) observations officialsandemployees oilwelldrilling origin planets popularworks raumfahrt research researchgoddardspaceflightcenter researchprincetonuniversity robotics rosetta(spacecraft) rovingvehicles(astronautics) spaceflight spaceprogram spacevehicles thesolarsystem