Related by context. Frequent words. (Click for all words.) 51 robotic probes 48 Astronauts inspect 46 Earthlings 46 NASA Kepler 45 Happiest Celebration 44 Earth 44 extraterrestrial beings 43 NASA rovers 43 Cassini Huygens 43 Exoplanet 42 robotic rover 42 Mars rovers Spirit 42 Magnificent Desolation 42 moonwalker 41 interplanetary spacecraft 41 Apollo astronauts 41 By JOE LAPOINTE 41 Lunar Reconnaissance Orbiter LRO 41 twin rover Spirit 41 orbiting Hubble Space Telescope 41 asteroid Ceres 41 NASA Cassini 41 outer space 41 robotic explorers 40 alien civilizations 40 Soviet cosmonaut Yuri Gagarin 40 Phil Plait 40 Carl Sagan 40 lunar orbiter 40 orbited Earth 39 PASADENA Calif. NASA 39 Mars Lander 39 spacecraft orbiting 39 Bad Astronomy 39 NASA Spacecraft 39 Gene Cernan 39 interplanetary missions 39 Ed Weiler 39 Kepler spacecraft 39 NASA Stardust spacecraft 39 earthlings 39 Nibiru 39 Nicolaus Copernicus 39 Compton Gamma Ray 39 Stardust spacecraft 38 Saturn moon 38 Robert Zubrin 38 unmanned lunar 38 Outer Space Treaty 38 extra terrestrials 38 Mars Rover 38 particle beam 38 GOES O 38 astronaut Yang Liwei 38 Planet Earth 38 HD #b [002] 38 JPL manages 38 extraterrestrials 38 planet 38 VSS Enterprise 38 Chang'eI 38 LCROSS mission 37 star Gliese 37 Mars rovers 37 Radiohead frontman Thom Yorke 37 COROT 37 Lunokhod 37 Stardust NExT 37 asteroid Vesta 37 invading aliens 37 rover Spirit 37 robotic spacecraft 37 comet Shoemaker Levy 37 Apollo missions 37 Voyager spacecraft 37 lunar missions 37 Earthlike planets 37 heliocentric 37 Martian dust 37 innermost planet 37 Messenger spacecraft 37 comet 37 Hayabusa probe 37 shuttle undocked 37 director Derek Hassmann 37 Sputnik satellite 37 NASA Fermi Gamma 37 planetoid 37 Teletran Sky Spy 37 astronaut Nicole Stott 37 planet Uranus 37 comet dust 36 Mars orbiter 36 Red Planet 36 Mars Odyssey orbiter 36 spacecrafts 36 unmanned spacecraft 36 Discovery undocked 36 satellites 36 Solar Dynamics 36 Giant Leap