Related by context. Frequent words. (Click for all words.) 70 NASA Kepler 61 COROT 61 Cassini Huygens 59 Stardust spacecraft 59 extrasolar planets 59 robotic spacecraft 59 extrasolar planet 58 exoplanet 58 exoplanets 58 Opportunity rover 57 NASA Lunar Reconnaissance 57 Titan Saturn 57 PASADENA Calif. NASA 57 super Earths 57 Kepler telescope 56 Mars orbiter 56 habitable planets 56 Saturn moon 56 Cassini spacecraft 56 orbiting observatory 56 orbiting spacecraft 56 rovers Spirit 55 Gliese #g 55 XMM Newton 55 NASA Cassini spacecraft 55 infrared telescope 54 rover Opportunity 54 orbiting Mars 54 rocky planets 54 planets 53 microlensing 53 Astronomers 53 Martian arctic 53 Saturn moon Enceladus 53 astrobiologists 53 unmanned lunar 53 New Horizons spacecraft 53 orbiting telescope 53 comet Wild 53 GLAST 53 spacecraft 52 moon Charon 52 planets orbiting 52 X ray telescope 52 asteroid 52 Phoenix Mars lander 52 Mars Reconnaissance Orbiter 52 CALIPSO 52 Earth asteroids 52 EPOXI 52 Mars rover Opportunity 52 orbiting 52 astronomers 51 twin rovers 51 GOCE 51 lunar orbiter 51 terrestrial planets 51 NASA Mars Odyssey 51 Saturn moons 51 Lunar Reconnaissance Orbiter 51 Cassini 51 Spitzer Space Telescope 50 MARSIS 50 Mars rovers 50 Mars lander 50 Phoenix lander 50 Deep Impact mission 50 moon Europa 50 outer planets 50 NASA Mars Reconnaissance 50 distant galaxy 50 brown dwarfs 50 cometary 50 Cancri 50 comet Hartley 2 50 Cassini orbiter 50 Kepler 50 Mars Pathfinder 50 NASA Hubble Space 50 Itokawa 49 ESA Mars 49 moon Titan 49 OGLE 49 Red Planet 49 Martian surface 49 asteroids 49 Space Telescope 49 MESSENGER 49 Oceansat 2 49 Mars Odyssey 49 Mars rover 49 Global Surveyor 49 planetary missions 49 Hubble Space Telescope 49 habitable planet 49 ExoMars 49 Very Large Array 48 HD #b [002] 48 planetary 48 NASA Deep Impact 48 Orion Nebula