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(Click for frequent words.) 69 Churyumov Gerasimenko 67 Fomalhaut b 66 planetary Transits 66 Comet Halley 66 Mars moon Phobos 66 Upsilon Andromedae 66 Nasa spacecraft 66 Comet Hartley 2 66 comet flyby 66 WISE spacecraft 65 airglow 65 Comet #P/Churyumov-Gerasimenko 65 Comet Lulin 65 innermost planet 65 IBEX spacecraft 64 Orbiter LRO 64 Comet Hartley 64 Solar TErrestrial RElations Observatory 64 NASA Cassini 64 exoplanets planets 64 Cassini flyby 64 retrograde orbit 64 comet Churyumov Gerasimenko 63 LORRI 63 Comet Churyumov Gerasimenko 63 Epsilon Eridani 63 Galileo spacecraft 63 orbiting 63 Evolution Explorer 63 Kepler 9c 63 Ultraviolet Imaging Spectrograph UVIS 63 Cassini 63 THEMIS satellites 63 Galilean moons 63 Cassini Huygens spacecraft 63 Mars Pathfinder lander 63 Mars landers 63 Upsilon Andromedae b 62 THEMIS spacecraft 62 comets orbiting 62 cosmic cannibal 62 Jovian moons 62 lunar equator 62 planet Uranus 62 Orbiter MRO 62 exo planets 62 Voyager spacecraft 62 Kuiper belt objects 62 Cancri e 62 thin crescent 62 Toutatis 62 WISE telescope 62 highly elliptical orbits 62 Martian rovers 62 gamma ray observatory 62 slender crescent 62 lunar landers 62 Mars Orbiter 62 Fermi telescope 62 elliptical orbits 62 Galilean satellites 62 reentry capsule 61 Nasa Mars Odyssey 61 celestial sphere 61 Saturn Enceladus 61 Convection Rotation 61 ESA Huygens probe 61 lunar orbits 61 Lunar Reconnaissance Orbiter LRO 61 Geminga 61 planet Gliese #g 61 gaseous planet 61 comet Hale Bopp 61 moons orbiting 61 Samuel Oschin Telescope 61 icy moons 61 exoplanetary 61 Ring Nebula 61 NASA EPOXI mission 61 planets orbits 61 asteroid Vesta 61 Galaxy Evolution 61 Cygnus Lyra region 61 Corot 7b 61 Viking orbiters 61 comet McNaught 61 asteroid Itokawa 61 Venusian 61 occultations 61 BepiColombo 61 flyby Cassini 61 flyby spacecraft 61 WISE infrared 61 waning crescent Moon 61 synchronous polar 61 NASA Stardust spacecraft 61 unmanned probes 61 Gliese #c 61 Kepler spacecraft 61 Saturnian system 61 moons Phobos 61 HiRISE camera aboard 61 Sojourner rover 61 Bonneville Crater 61 Saturnian moons 61 Wolszczan 61 orbiting Saturn 61 transiting exoplanet 61 interplanetary spacecraft 61 CoRoT satellite 60 spacecraft 60 Ulysses spacecraft 60 smallest exoplanet 60 Foton M3 60 spacecraft Cassini 60 Explorer WISE 60 Titan flyby 60 NASA STEREO 60 orbiting Kepler telescope 60 Kuiper Belt Objects 60 superheated gases surrounding 60 Rosetta spacecraft 60 Saturnian moon Titan 60 Solar Dynamics Observatory 60 exosphere 60 moon Io 60 spacecraft flyby 60 Rosetta lander 60 ESA Rosetta 60 retroreflector 60 Pleiades cluster 60 Cassini Huygens 60 asteroid Steins 60 lobate scarps 60 P/# A2 60 Kuiper Belt Object 60 Stardust capsule 60 Stardust spacecraft 60 stellar occultation 60 sunlike star 60 Zeta Ophiuchi 60 Comet 9P/Tempel 1 60 Pluto Charon 60 NASA MESSENGER spacecraft 60 jovian 60 moon Phobos 60 MARSIS radar 60 orbited Jupiter 60 Curiosity rover 60 NASA LCROSS 60 ESA Planck 60 robotic explorer 60 Gerard Kuiper 60 orbital rendezvous 59 waning gibbous 59 infrared telescopes 59 orbits 59 Hubble orbits 59 lunar meteorites 59 Saturn moons Titan 59 outer planets 59 comet chaser 59 COROT 7b 59 Philae lander 59 synchronous orbit 59 zodiacal light 59 orbiter 59 outermost planets 59 Atlantis undocks 59 Manned missions 59 Mini TES 59 APXS 59 galaxy M# [001] 59 interstellar dust particles 59 moons circling 59 protoplanet 59 cometary debris 59 HiRISE 59 Deep Impact flyby spacecraft 59 Mars Reconnaissance Orbiter MRO 59 moon Mimas 59 spacecraft orbited 59 KBOs 59 Huygens lander 59 Comet Machholz 59 extrasolar 59 planets Uranus 59 orbit 59 Shackleton Crater 59 Saturn moons 59 NEAR Shoemaker 59 Valles Marineris canyon 59 O OREOS 59 Phoebe orbits 59 orbiting spacecraft 59 Nasa Kepler 59 Perseus Cluster 59 COROT 59 EPOXI spacecraft 59 NASA THEMIS 59 MARSIS instrument 59 Saturn rings 59 elongated orbits 59 Jenniskens 59 Opportunity Mars rover 59 Oort cloud 59 Quadrantid meteor shower 59 constellation Hercules 59 planetary nebulas 59 moon Mab 59 Olympus Mons 59 Heliospheric Observatory SOHO 59 ecliptic plane 59 OGLE TR #b 59 Martian terrain 58 Mars Phobos 58 #P/Churyumov-Gerasimenko 58 comets asteroids 58 HiRISE image 58 HiRISE camera 58 constellation Eridanus 58 irregularly shaped asteroid 58 Huygens mission 58 Jupiter Ganymede 58 whiz harmlessly 58 Ringed Planet 58 Nasa Mars Reconnaissance 58 Cometary 58 planets circling stars 58 Planck satellite 58 ESA ASI 58 Jupiter icy moons 58 Cassini spacecraft orbiting 58 Mercury flyby 58 Oort Cloud 58 ESA Integral 58 THEMIS 58 TrES 4 58 Deep Impact comet 58 MESSENGER spacecraft 58 Saturn moon 58 Pleiades star 58 EPOXI mission 58 SIRTF 58 constellation Aquarius 58 exosolar planets 58 Odyssey orbiter 58 VIRTIS 58 spacecraft orbiting 58 Neptune Uranus 58 prograde 58 moonlet 58 Quadrantids 58 Hubble 58 Relations Observatory STEREO 58 Charon Pluto 58 orbiting observatories 58 Saturnian 58 Orionids 58 polar craters 58 NASA Lunar Prospector 58 highly elliptical orbit 58 Proxima Centauri 58 MG J# +# 58 Comet NEAT 58 closest flyby 58 planets orbiting stars 58 inhabitable planets 58 Tempel Tuttle 58 permanently shadowed craters 58 orbital solitude 58 Meridiani plains 58 interstellar particles 58 Solar Orbiter 58 rocky extrasolar planet 58 constellation Carina 58 Saturn outermost moon 58 Cassini Equinox 58 spacecraft Chandrayaan 1 58 orbiting Hubble Space Telescope 58 circumstellar disks 58 HD#b 58 comet 58 Orion nebula 58 spiral galaxy Messier 58 Epsilon Aurigae 58 Cassini Huygens Mission 58 Deep Impact eXtended Investigation 58 Aqua satellite 58 ESA Mars 58 martian 58 Reconnaissance Orbiter 58 Mars Reconnaissance Orbiter 58 Saturnian moon 58 moon Ganymede 58 BLG #Lb 58 spiral galaxy NGC 58 comet Wild 58 lunar craters 58 star Spica 58 Endurance crater 58 planets orbiting sun 58 Ranging spacecraft 58 GALEX 58 binary asteroid 58 planets moons 58 rover Opportunity 58 SIM PlanetQuest 57 moon Charon 57 Martian polar 57 waxing crescent 57 asteroid Eros 57 NASA Cassini spacecraft 57 Mars CRISM 57 Gerhard Schwehm 57 Flyby spacecraft 57 ESA Huygens 57 cometary 57 ESA Herschel 57 Kepler #b 57 orbital inclination 57 Jupiter flyby 57 Giovanni Cassini 57 Eridanus 57 Predator drone flies 57 Uranus Jupiter 57 Kepler Space Telescope 57 Cassini spacecraft 57 Gusev crater 57 ringed planet 57 S/# P2 57 twin Voyager spacecraft 57 RXTE 57 Planetary Transits 57 coronal loops 57 Opportunity rover 57 Mini Thermal Emission 57 Observatory SDO 57 Viking Lander 57 VY Canis Majoris 57 Valles Marineris 57 Mars 57 outer corona 57 Kuiper belt object 57 planets asteroids 57 penumbral shadow 57 ESA GOCE 57 planet HD#b 57 moons 57 Mars Lander 57 comet nucleus 57 Jovian moon 57 twin rover Opportunity 57 Methone 57 DISR 57 subsurface ocean 57 AU Mic 57 sunlike stars 57 moons orbiting Saturn 57 X ray observatory 57 Epoxi 57 rover Spirit 57 KAGUYA 57 Syrtis Major 57 robotic rovers 57 MARSIS 57 GJ#b 57 moonlets 57 enters lunar orbit 57 Titan Saturn 57 Earthlike planets 57 laser altimeter 57 Venusian atmosphere 57 geo stationary orbit 57 Martian surface 57 trans Neptunian objects 57 Rosetta orbiter 57 shadowy craters 57 Kuiper Belt objects 57 moon Deimos 57 NASA Voyager spacecraft 57 super perigee moon 57 microlensing events 57 Exoplanet 57 LADEE 57 meteoroid 57 Comet Holmes 57 magnetotail 57 smoothest flattest spot 57 Omega Centauri 57 Herschel telescope 57 Andromeda Galaxy 57 Krimigis 57 GJ #b [002] 57 Dumbbell Nebula 57 exo planet 57 heavily cratered 57 retrograde orbits 57 Mars orbiting spacecraft 57 CoRoT 9b 57 Huygens 57 lander 57 Kepler Mission 57 Chajnantor plateau 57 asteroids orbiting 57 KH #D 57 Coma cluster 57 Mars Opportunity rover 57 Saturn moon Mimas 57 visit http:/saturn.jpl.nasa.gov 56 THEMIS Images 56 Cassini flybys 56 Pancam 56 manned Shenzhou 56 Comet Encke 56 waning crescent 56 Ed Weiler NASA 56 Mandushev 56 SOHO spacecraft 56 Enceladus flybys 56 circular orbit 56 interstellar dust samples 56 Rosette Nebula 56 Jupiter Icy Moons 56 NFIRE satellite 56 SKY WATCH 56 noctilucent clouds 56 NASA twin rovers 56 WASP #b 56 Martian crater 56 geostationary orbits 56 spaceweather.com 56 Cosmic Microwave Background 56 Titan flybys 56 Herschel Space Telescope 56 Uranus Neptune 56 Earth magnetotail 56 Martian craters 56 planets 56 northern arctic plains 56 mu Arae 56 NASA rover Spirit 56 Context Camera 56 ray Space Telescope 56 Mössbauer 56 Yinghuo 1 56 NASAs 56 Global Surveyor 56 amateur skywatchers 56 Flyby 56 SN #A 56 Nasa 56 Descent Imager Spectral Radiometer 56 planetary surfaces 56 interstellar cloud 56 flyby 56 asteroidal 56 geo synchronous 56 Mars Color Imager 56 NASA rovers 56 Sputnik beeped 56 Shuttle Atlantis blasts 56 Shackleton crater 56 photosphere 56 twin STEREO spacecraft 56 gravitational perturbations 56 comet Tempel Tuttle 56 NuSTAR 56 Discovery undocks 56 Martian dust 56 Hellas Basin 56 orbiting Mars 56 Saturn outermost ring 56 Moderate Resolution Imaging 56 orbital 56 IRAS #-# 56 starlike object 56 Bug Nebula 56 Butterfly Nebula 56 comet #P/Churyumov-Gerasimenko 56 Candor Chasma 56 rover Sojourner 56 NASA Kepler spacecraft 56 XMM Newton 56 Mars rovers Opportunity 56 Opportunity rovers 56 lunar crust 56 phyllosilicates 56 extrasolar planet 56 constellation Andromeda 56 comets meteors 56 entire Milstar constellation 56 Martian rover 56 Neutron Spectrometer 56 constellation Taurus 56 Red Rectangle 56 Endeavour undocks 56 Orientale Basin 56 Venusian surface 56 Martian equator 56 Nasa Jet Propulsion 56 filamentary structure 56 New Horizons spacecraft 56 Shepherding Spacecraft 56 Deep Impact craft 56 STEREO spacecraft 56 Saturn Jupiter Uranus 56 Diviner instrument 56 constellation Aquila 56 icy comets 56 Martian 56 Shallow Subsurface Radar 56 Huygens descent 56 elliptical polar 56 Beta Pictoris b 56 NASA Spacecraft 56 martian rocks 56 orbiting gamma ray 56 NanoSail D 56 accretion disks 56 Planck telescope 55 smallest exoplanets 55 http:/saturn.jpl.nasa.gov 55 shadowed craters 55 Composite Infrared Spectrometer 55 Solar System 55 Saturn moon Iapetus 55 constellation Scorpius 55 hubble 55 Mars Pathfinder 55 axial tilt 55 sized planets orbiting 55 Jupiter Uranus 55 volcanic moon Io 55 MESSENGER 55 Comet LINEAR 55 comet Lulin 55 planets comets 55 Diviner 55 exoplanets orbiting 55 satellites orbiting Earth 55 Io Europa 55 fainter objects 55 mere fly bys 55 zodiac constellations 55 lunar orbiters 55 hydroxyl molecules 55 distant galaxy 55 globulars 55 gibbous moon 55 planetary transits 55 Comet Tempel Tuttle 55 WISE mapped 55 Martian arctic 55 Optical Spectroscopic 55 CoRoT 7b 55 Messenger spacecraft 55 Shuttle undocks 55 largest moon Charon 55 Earthlike planet 55 Isidis Planitia 55 Hubble Space Telescope HST 55 NASA rovers Spirit 55 comet particles 55 Shenzhou VI capsule 55 Orionid meteors 55 orbits Saturn 55 Discovery undocked 55 Great Observatories 55 rover panoramic 55 habitable worlds 55 Sombrero Galaxy 55 exoplanet orbiting 55 coronal holes 55 NASA ICESat 55 Saturn outermost 55 Stardust NExT 55 ejecta blanket 55 waxing gibbous 55 thin crescent moon 55 durable twin rovers 55 planet orbits 55 Itokawa asteroid 55 Mars Odyssey spacecraft 55 Martian rocks 55 Helix Nebula 55 protoplanetary 55 Encke gap 55 galactic mergers 55 Earth magnetosphere 55 Comet Hale Bopp 55 Muchachos Observatory 55 planet HD #b 55 Super Earths 55 GJ #b [001] 55 sols 55 NASA Cassini orbiter 55 perihelion 55 interstellar dust grains 55 Earth radii 55 Foing 55 telescopic observations 55 ESA SMART 55 LCROSS spacecraft 55 ah dus 55 Global Surveyor spacecraft 55 Thermal Emission Spectrometer 55 lander Philae 55 solar corona 55 NASA Kepler telescope 55 SMOS 55 mineral olivine 55 bedrock outcropping 55 Hale Bopp 55 telescope eyepiece 55 High Resolution Imaging 55 Mimas 55 N. Rathnasree 55 GRB #B 55 celestial equator 55 Exoplanets 55 moon Enceladus 55 lensing galaxy 55 Kuiper Belt object 55 constellation Ursa Major 55 Beta Pictoris 55 Gliese #d 55 geyser plumes 55 Orion Nebula 55 Pluto Eris 55 planet magnetosphere 55 GQ Lupi 55 LROC 55 planets astronomers 55 stationary lander 55 orbital resonance 55 Jupiter moons 55 Caloris Basin 55 DIXI 55 brightest supernova 55 Earth asteroid Itokawa 55 millisecond pulsar 55 Gliese #e 55 Kepler Telescope 55 circumstellar 55 stellar occultations 55 planemos 55 Ocean Salinity SMOS 55 Planck spacecraft 55 Lagoon Nebula 55 STSS Demo 55 LRO spacecraft 55 SN #D 55 Mars Squyres 55 moonquakes 55 Cosmonaut Yuri Gagarin 55 rovers Spirit 55 HL Tau 55 Infrared Array Camera 55 NASA Kepler 55 robotic spacecraft 55 inner Oort Cloud 55 orbital eccentricity 55 Comet #P 55 star Fomalhaut 54 ESA XMM Newton 54 Eagle lunar lander 54 SHARAD 54 celestial observations 54 duration spaceflights 54 Terra Meridiani 54 Enceladus 54 Andromeda galaxy 54 EPOCh 54 NEOWISE 54 Triangulum Galaxy 54 Jupiter moon Io 54 Lunar CRater Observation 54 Peony nebula star 54 gamma ray spectrometer 54 polar orbits 54 Great Orion Nebula 54 moon 54 Mars rovers Spirit 54 Stephan Quintet 54 Shuttle Endeavor 54 Eric Becklin 54 NEAs 54 Elenin 54 microscopic imager 54 meteoroid impacts 54 X ray telescopes 54 Sun synchronous orbit 54 Emily Lakdawalla 54 THEMIS Image 54 Halley comet 54 globular cluster M# 54 nebular 54 Lunokhod 54 eccentric orbits 54 Hubble Space telescope 54 windshield wiper maneuver 54 Geminid meteors 54 OSIRIS REx 54 orbited 54 Red Planet 54 NASA 54 zodiacal constellations 54 icy moon Enceladus 54 imaging spectrometer 54 Viking landers 54 Mars Orbiter Camera 54 Orion constellation 54 NASA Lunar Reconnaissance 54 lunar meteorite 54 Hubble telescope 54 constellation Virgo 54 galaxy NGC 54 supergiant stars 54 HD #b [002] 54 circular orbits 54 ATV Johannes Kepler 54 filamentary structures 54 NASA Spirit rover 54 SBSS satellite 54 orbiter Cassini 54 aphelion 54 ESO VLT 54 HD #b [001] 54 Cassini Image 54 NASA Interstellar Boundary 54 copper impactor 54 Swift Tuttle 54 Caloris 54 radial velocity technique 54 Meridiani 54 Gliese #G 54 GEochemistry 54 merging galaxies 54 JIMO 54 millisecond pulsars 54 asteroid Lutetia 54 Proba 2 54 humanoid robot bound 54 Herschel Space 54 ecliptic 54 CoRoT 54 Space Infrared Telescope 54 Corot 9b 54 Vourlidas 54 Boethin 54 Spitzer infrared 54 constellation Centaurus 54 SpaceWeather.com 54 faint smudge 54 Hubble Telescope 54 Wilkinson Microwave Anisotropy Probe 54 circumlunar 54 Fomalhaut 54 RY Sagittarii 54 Atlantis Undocks From 54 Solar Terrestrial Relations 54 periodic dimming 54 martian surface 54 Lulin 54 Martian landscape 54 Voyager probes 54 Cosmic Evolution 54 Shuttle Docks 54 Earthlike 54 Astronauts inspect 54 spaceward 54 Dean Pesnell 54 lander rover 54 Mars rover 54 distant supernovas 54 BP Psc 54 Galactic cosmic rays 54 asteroids Ceres 54 carbonaceous chondrite 54 Kuiper belt 54 Horsehead Nebula 54 onboard Chandrayaan 54 OMEGA instrument 54 Jupiter magnetosphere 54 magnetospheric 54 EPOXI 54 urine recycler 54 axis perpendicular 54 Eta Aquarid meteor shower 54 solar prominences 54 infrared telescope 54 arctic plains 54 giant elliptical galaxy 54 albedo reflectivity 54 Foton spacecraft 54 auroral displays 54 Apollo missions 54 Chang'eI 54 asteroids comets 54 lunar perigee 54 potentially habitable 54 P Churyumov Gerasimenko 54 Wolf Rayet stars 54 Leonid meteor showers 54 Canadian Julie Payette 54 pulsating aurora 54 Victoria Crater 54 exoplanets planets outside 54 Today waxing Virgo 54 galactic halo 54 NASA Opportunity rover 54 gaseous planets 54 crewed spacecraft 54 Hubble Space 54 permanently shadowed regions 54 hydrated minerals 54 cometary dust 54 AB Aurigae 53 cluster NGC 53 Jupiter Saturn 53 Comet Tempel 1 53 Infrared Astronomy SOFIA 53 cosmological distances 53 NASA Solar Terrestrial 53 spokesman Paul Foerman 53 gibbous 53 equatorial latitudes 53 GOES O 53 LRO LCROSS 53 PSR B# +# 53 magma ocean 53 crescent Moon 53 called lobate scarps 53 Espenak 53 NASA Hubble Space 53 Aurigid 53 Infrared Astronomical Satellite IRAS 53 rover 53 Arsia Mons 53 Hayabusa probe 53 NASA MESSENGER 53 Spirit Mars rover 53 NASA Gamma ray 53 galactic disk 53 planets constellations 53 astrophysical phenomena 53 orbit GEO 53 solar radii 53 Hot Jupiters 53 carry heavier payloads 53 Express orbiter 53 binary quasar 53 CRISM 53 Bonnie Buratti 53 interstellar boundary 53 Itokawa 53 Martian meteorites 53 hematite mineral 53 Shuttle Discovery docks 53 Konacki 53 NGC #A 53 Imaging Spectroradiometer MODIS instrument 53 sundog 53 Spitzer infrared spectrograph 53 Saturn moons Enceladus 53 Oefelein piloted 53 Libra constellation Vogt 53 Infrared Pathfinder Satellite 53 Spudis 53 rotational axis 53 circumstellar disk 53 GOCE satellite 53 Dynamics Observatory 53 Shenzhou spacecraft 53 robot rovers 53 sun corona 53 Lutetia 53 thruster rockets 53 Launch Scrubbed 53 rovers 53 geosynchronous satellites 53 Goldilocks planet 53 VIRTIS instrument 53 Martian orbit 53 Spitzer Space Telescopes 53 Cabeus crater 53 Interstellar Boundary Explorer 53 robotic landers 53 George Zamka 53 Mössbauer spectrometer 53 Eagle Nebula 53 extravehicular activities 53 lunar regolith 53 extrasolar planets 53 transiting planets 53 Explorer GALEX 53 Phobos Grunt 53 hexagonal mirrors 53 electric ion propulsion 53 prominences 53 Ontario Lacus 53 inner asteroid belt 53 X ray Telescope XRT 53 lunar soil 53 celestial phenomena 53 planetary missions 53 permanently shadowed crater 53 constellation Pegasus 53 Hinode 53 Martian moons Phobos 53 NASA Wilkinson Microwave 53 orbital insertion 53 RS Ophiuchi 53 gravitational lenses 53 Huygens probe 53 Cloud Aerosol Lidar 53 gravitational tides 53 moondust 53 Lunar Crater 53 Pete Theisinger 53 ST5 53 orbiting telescope 53 Chandrayaan II 53 Submillimeter Array 53 Earth orbit 53 Heliospheric Observatory 53 heliospheric 53 Taurids 53 elongated orbit 53 PSLV C6 53 Perseid shower 53 Tarantula Nebula 53 Comet McNaught 53 S/# S1 53 Cepheid variables 53 Fermi Telescope 53 robotic lander 53 HD# [002] 53 star Beta Pictoris 53 Space ENvironment GEochemistry 53 dwarf spheroidal 53 planetary geologists 53 Gliese #g 53 outermost planet 53 protoplanets 53 Lunar Reconnaissance Orbiter Camera 53 Eta Aquarids 53 extrasolar planets orbiting 53 amateur astronomers peering 53 orbited Earth 53 Helios 2B 53 Mini SAR 53 wheeled rovers 53 GOCE 53 STEREO mission 53 inch Samuel Oschin 53 LCROSS 53 lunar 53 Titan smoggy 53 RRATs 53 NFIRE 53 Neptune Jupiter 53 Stardust NExT mission 53 Earth orbiting satellites 53 Origins Spectral Interpretation 53 Space Telescope GLAST 53 Dalcanton 53 Saturn moon Enceladus 53 Spacecraft 53 terra forming 53 director Charles Elachi 53 Shuttle Discovery blasts 53 Maunder minimum 53 detect gravitational waves 53 RQ# 53 NASA Stratospheric Observatory 53 distant supernovae 53 waxing gibbous moon 53 ESO telescopes 53 constellation Cygnus 53 dust enshrouded 53 comet tail 53 earthlike planets 53 Crab Nebula 53 HM Cancri 53 orbital velocity 53 crystalline silicates 53 Astronauts Install 53 substorm 53 Lunar Prospector 53 Soyuz landings 53 Pluto Kuiper Belt 53 orbiter Mars Odyssey 53 Hyakutake 53 Hipparcos 53 Antarctic Dry Valleys 53 lunar surface 53 layered bedrock