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(Click for frequent words.) 65 APXS 65 Mössbauer 64 neutron spectrometer 63 spectroscopically 63 Orbiter LRO 63 stellar occultations 62 X ray spectrometer 62 retroreflector 62 martian meteorites 62 gamma ray spectrometer 61 airglow 61 Wilkinson Microwave Anisotropy Probe 61 lunar craters 61 WMAP satellite 61 Mars CRISM 61 Anisotropy Probe 61 polarimetry 61 Composite Infrared Spectrometer 61 distant quasars 60 photometer 60 NASA Wilkinson Microwave 60 radar altimetry 60 spectral characteristics 60 laser altimeter 60 ray Space Telescope 60 Corot 7b 60 Cosmic Microwave Background 60 Cassini flyby 60 imaging spectrometer 59 extrasolar 59 NASA Cassini spacecraft 59 cosmological distances 59 spectrographic 59 Ulysses spacecraft 59 Epsilon Eridani 59 occultations 59 mineralogical composition 59 planet Gliese #g 59 spectroscopic measurements 59 SDSS II 59 Planck satellite 59 Upsilon Andromedae 59 VIRTIS 59 HiRISE image 59 RHESSI 59 spectroscopic observations 58 Hipparcos 58 THEMIS satellites 58 Lunar Orbiter Laser Altimeter 58 permanently shadowed craters 58 NASA THEMIS 58 smallest exoplanet 58 Diviner instrument 58 SPICAM 58 X ray telescopes 58 gamma ray observatory 58 jovian 58 Kepler Mission 58 SeaWiFS 58 polar craters 58 YORP effect 58 Saturn Enceladus 58 Advanced Microwave Scanning 58 infrared spectra 58 noctilucent clouds 58 twin STEREO spacecraft 58 magnetospheric 58 GALEX 58 Cassini radar 58 orbiter Mars Odyssey 58 Cepheid variables 58 NASA Cassini 58 lunar meteorites 58 magma ocean 57 radial velocity technique 57 Planetary Transits 57 lobate scarps 57 NASA WMAP 57 SIRTF 57 Imaging Spectrometer 57 Fermi LAT 57 exo planet 57 Fermi Gamma ray 57 Landsat satellite 57 lunar crust 57 radiometers 57 moon Enceladus 57 radio occultation 57 Anisotropy Probe WMAP 57 distant supernovae 57 moonquakes 57 polarimetric 57 Spectroscopic 57 MARSIS 57 orbiting gamma ray 57 planetary Transits 57 EPOCh 57 Helioseismic 57 retrograde orbit 57 ESO VLT 57 Viking landers 57 DISR 57 eclipsing binary 57 Panoramic Camera 57 MG J# +# 57 Fermi telescope 57 Ultraviolet Imaging Spectrograph UVIS 57 binary quasar 57 Hubble observations 57 Triangulum Galaxy 57 spatially resolved 57 Spectrograph 57 Climate Experiment GRACE 57 COROT 7b 57 Convection Rotation 57 lunar equator 57 biosignatures 57 ESA Planck 57 Mars Reconnaissance Orbiter MRO 57 AKARI 57 exoplanetary 57 Thermal Emission Spectrometer 57 THEMIS 56 telescopic observations 56 microlensing events 56 Pancam 56 Cometary 56 rover panoramic 56 Orbiter MRO 56 LRO spacecraft 56 Gusev crater 56 radiometer 56 ChemCam 56 spacecraft orbiting 56 Compact Reconnaissance Imaging Spectrometer 56 THEMIS Images 56 HiRISE camera aboard 56 HD#b 56 Moon Mineralogy Mapper M3 56 IBEX spacecraft 56 Gliese #c 56 Evolution Explorer 56 Heterodyne Instrument 56 WISE infrared 56 Cassini ultraviolet 56 Lunar Reconnaissance Orbiter LRO 56 AB Aurigae 56 exoplanets planets 56 G#.# +#.# 56 Infrared Astronomical Satellite IRAS 56 interstellar dust grains 56 backscattered 56 extrasolar planetary systems 56 Neutron Detector 56 astrometry 56 photometry 56 Solar Dynamics Observatory 56 Voyager spacecraft 56 Comet Halley 56 Martian meteorites 56 geoneutrinos 56 Corot 9b 56 Lunar Reconnaissance Orbiter Camera 56 XMM Newton 56 THEMIS Image 56 spectrometric 56 NASA Far Ultraviolet 56 GJ #b [001] 56 Antarctic Dry Valleys 56 substorm 56 Kuiper Belt Objects 56 constellation Eridanus 56 NASA ICESat 56 earthshine 56 Ontario Lacus 56 spectrographs 56 martian soil 56 moons Phobos 56 Philae lander 56 composite infrared spectrometer 56 Mössbauer spectrometer 56 NASA Cosmic Background 56 Stadermann 56 oxygen isotopic 56 Herschel telescope 56 Mercury flyby 56 Galactic Plane 56 HiRISE images 56 permanently shadowed regions 56 ESA Envisat satellite 56 periodicities 56 galaxy M# [001] 56 coronagraph 56 Ozone Monitoring 56 Cepheids 55 J# +# [002] 55 diffraction patterns 55 Hubble Space Telescope HST 55 Crab Pulsar 55 NASA Fermi Gamma 55 crustal thickness 55 asteroseismology 55 UVOT 55 RXTE 55 Neutron Spectrometer 55 Cosmic Background Explorer COBE 55 Saturn Cassini 55 Galaxy Evolution 55 millisecond pulsar 55 ESA ERS 55 cosmic ray flux 55 tropospheric 55 Mini TES 55 lunar regolith 55 circumstellar 55 stellar occultation 55 particle acceleration 55 NASA Lunar Reconnaissance 55 mantle plumes 55 STEREO spacecraft 55 coronal loops 55 phyllosilicate 55 Opportunity rover 55 Carina constellation 55 TrES 4 55 NASA QuikScat satellite 55 Heliospheric Observatory SOHO 55 constellation Aquarius 55 Gerard Kuiper 55 CoRoT satellite 55 CRISM 55 Titan flybys 55 Exoplanet 55 spacecraft orbited 55 SINFONI 55 extrasolar planet 55 planet Gliese #c 55 evaporite deposits 55 SNR #-#.# 55 NASA Lunar Prospector 55 extrasolar planets orbiting 55 crystalline silicates 55 Cancri e 55 Astrophysical 55 bolometers 55 Muchachos Observatory 55 Nasa Mars Reconnaissance 55 electron ion 55 EPOXI spacecraft 55 Oscillations 55 Cosmic Evolution 55 Martian craters 55 solar corona 55 Ultraviolet Imaging Spectrograph 55 Mossbauer 55 gravitational lenses 55 atmospheric aerosols 55 Mars orbiting spacecraft 55 GRB# 55 Martian dust 55 planets orbiting distant 55 circumstellar disks 55 planetary atmospheres 55 Exoplanets 55 spacecraft Cassini 55 interferometric 55 AGNs 55 Mauna Kea Hawaii 55 neutral mass spectrometer 55 Mars Odyssey Orbiter 55 Shackleton crater 55 Raman spectra 55 transiting planet 55 Reiner Gamma 55 Cydonia region 55 Kuiper belt objects 54 Magnetic Imager HMI 54 NASA Interstellar Boundary 54 auroral 54 sulfur isotope 54 radiotelescope 54 ESA Integral 54 WMAP 54 planet Uranus 54 Tau Ceti 54 Mars Climate Sounder 54 protoplanetary disk 54 Earthlike planets 54 ARPES 54 ICESat 54 astronomical observations 54 Galileo spacecraft 54 Mars landers 54 orbiting spacecraft 54 gravitational lens 54 intracluster 54 GJ #b [002] 54 Nikku Madhusudhan 54 infall 54 stellar seismology 54 microlensing 54 SMOS 54 Mars Color Imager 54 WISE telescope 54 Huygens descent 54 Gamma ray 54 IRC +# 54 Delta Cephei 54 Samuel Oschin Telescope 54 ultraviolet wavelengths 54 Cabeus 54 Gravity Recovery 54 HD #b [002] 54 icy comets 54 transiting planets 54 ESO PR 54 exoplanetary systems 54 gravitational microlensing 54 ultracold atoms 54 CMB radiation 54 astrometric 54 KBOs 54 particle analyzers 54 Cassini ion 54 periodic dimming 54 Valles Marineris 54 Descent Imager Spectral Radiometer 54 rocky extrasolar planet 54 lunar topography 54 KAGUYA 54 GRB #B 54 Ring Nebula 54 Reflection Radiometer 54 electron neutrinos 54 Planck telescope 54 BLG #Lb 54 icy moons 54 infrared spectral 54 photosphere 54 shadowed craters 54 microwave radiometers 54 Bug Nebula 54 magnetic polarity 54 Climate Sounder 54 Robotic Arm Camera 54 Earth ionosphere 54 spectral bands 54 Hawaii Mauna Kea 54 Cat Paw Nebula 54 transiting exoplanets 54 mantle convection 54 Spitzer infrared spectrograph 54 waxing crescent 54 Mini SAR 54 Explorer GALEX 54 ecliptic plane 54 extrasolar planetary 54 Clementine spacecraft 54 Syrtis Major 54 gamma rays emitted 54 NASA Mars Odyssey 54 hydrated minerals 54 silicate dust 54 Neutral Mass Spectrometer 54 Mars Odyssey spacecraft 54 COROT 54 RS Ophiuchi 54 Nasa spacecraft 54 Milky Way halo 54 axial tilt 54 Keck Interferometer 54 infrared spectrometers 54 arcminutes 54 Rosetta orbiter 54 azimuthal 54 Solar TErrestrial RElations Observatory 54 DEIMOS 54 planemos 54 frequency combs 54 Maunder minimum 54 ultraviolet imaging spectrograph 54 GJ#b 54 OGLE TR #b 54 proplyds 54 telescope atop Mauna 54 Aqua satellite 54 Earthshine 54 Wilkinson Microwave Probe 54 Lunar Laser Ranging 54 journal Icarus 54 Olympus Mons 54 planet HD #b 54 flyby Cassini 54 NASA COBE satellite 54 Keck telescope 54 Astrophysics Cambridge Mass. 54 Veil Nebula 54 meridional flow 54 Ken Herkenhoff 54 interstellar clouds 54 paleomagnetic 53 Sounder AIRS instrument 53 maser 53 Mars Orbiter Camera 53 orbiting observatories 53 Quadrantid meteor shower 53 GRB #A 53 Herschel Space 53 Suzaku 53 Fomalhaut b 53 perchlorate salts 53 elemental composition 53 Lunar Prospector 53 Alpha Particle 53 X ray wavelengths 53 antineutrino 53 Ground penetrating radar 53 millimeter wavelengths 53 SCIAMACHY 53 extragalactic 53 radial velocity 53 diffraction pattern 53 Saturnian moons 53 de Pater 53 intrinsic brightness 53 phyllosilicates 53 comets orbiting 53 Atmospheric Infrared Sounder 53 ESA XMM Newton 53 Shepherding Spacecraft 53 Microlensing 53 NASA Odyssey orbiter 53 mu Arae 53 BepiColombo 53 Alfven waves 53 basaltic rocks 53 LADEE 53 Nasa Kepler 53 NASA Atmospheric Infrared 53 Infrared Thermal Imaging Spectrometer 53 spaceborne 53 Shackleton Crater 53 HUDF 53 auroral emissions 53 brightnesses 53 Global Surveyor 53 filamentary structure 53 spectroscopic analysis 53 constellation Virgo 53 microscopic imager 53 THEMIS spacecraft 53 Global Surveyor spacecraft 53 constellations Cygnus 53 Extrasolar Planet Observation 53 ESO telescope 53 situ measurements 53 infrared telescopes 53 IKAROS 53 Spectrometers 53 submillimetre wavelengths 53 asteroidal 53 Lander robotic arm 53 NASA Kepler telescope 53 Hinode spacecraft 53 exo planets 53 X ray observatories 53 Mars Orbiter 53 waning gibbous 53 multispectral 53 Kepler #b 53 Mission SRTM 53 Saturn moons 53 Beta Pictoris 53 Red Rectangle 53 ESA Envisat 53 Phoenix Microscopy Electrochemistry 53 SN #A 53 interstellar cloud 53 STEREO satellites 53 Galilean satellites 53 comet McNaught 53 Submillimeter Array 53 TrES 53 distant supernovas 53 Solar Optical Telescope 53 XTE J# 53 EPOXI 53 Total Ozone Mapping 53 magnetotail 53 NASA STEREO 53 Comet Tempel Tuttle 53 Io Europa 53 Trifid Nebula 53 protoplanetary disks 53 Mars Pathfinder lander 53 OMEGA instrument 53 laser spectroscopy 53 DEEP2 53 NASA Mars Reconnaissance 53 NASA LCROSS 53 photoelectron 53 SIRAL 53 merging galaxies 53 Mars Reconnaissance Orbiter 53 constellation Sagittarius 53 hexagonal mirrors 53 VB #b 53 x ray fluorescence 53 dynamical evolution 53 UVIS 53 Giovanni Cassini 53 masers 53 penetrating radar 53 Context Camera 53 Mercury magnetosphere 53 earthlike planets 53 Imaging Spectroradiometer MODIS instrument 53 gamma ray detector 53 THEMIS mission 53 Saturnian moon 53 Infrared Mapping Spectrometer VIMS 53 lunar poles 53 ultraviolet radiation emitted 53 planetary transits 53 magnetic reconnection 53 spacecraft flyby 53 infrared observatory 53 Orion nebula 53 Pluto Charon 53 NASA rovers Spirit 53 Yinghuo 1 53 neutrino oscillations 53 Keck telescopes 53 Moessbauer spectrometer 53 spectroscopic 52 plasma spectrometer 52 MARSIS radar 52 Moderate Resolution Imaging 52 lunar surface 52 luminous galaxies 52 Mossbauer spectrometer 52 martian 52 faintest galaxies 52 Spitzer infrared 52 gaseous planet 52 scanning electron microscope SEM 52 VLTI 52 outer corona 52 Meridiani 52 subsurface ocean 52 polar caps 52 emit X rays 52 Jovian moons 52 lunar highlands 52 optical interferometry 52 Jenniskens 52 moons orbiting 52 Comet Lulin 52 NIRSpec 52 CIRS 52 nucleosynthesis 52 Epoxi 52 NASA CloudSat 52 Gas Chromatograph Mass Spectrometer 52 APEX telescope 52 sunlike stars 52 Cassini flybys 52 Cassini 52 planets comets 52 X ray observatory 52 Martian rovers 52 spectrometer 52 constellation Centaurus 52 magnetic substorms 52 Infrared Array Camera 52 Observatory SDO 52 planetary astronomer 52 lunar soil 52 X ray emission 52 nebular 52 Storrie Lombardi 52 Fossae 52 Viking Lander 52 heliospheric 52 ejecta 52 Butterfly Nebula 52 RPWS 52 Arsia Mons 52 electron diffraction 52 interplanetary spacecraft 52 Nili Fossae 52 HESS telescopes 52 Caloris 52 Gravity Probe 52 constellation Carina 52 submillimetre 52 VY Canis Majoris 52 isotopic ratios 52 planets orbiting sun 52 moon Mab 52 Moon Mineralogy Mapper 52 NASA MODIS 52 microshutters 52 Hubble orbits 52 AMSR E 52 WISE spacecraft 52 Infrared Mapping Spectrometer 52 MINOS 52 Omega Nebula 52 Great Orion Nebula 52 Itokawa 52 LORRI 52 ESA SMART 52 neutrino detectors 52 robotic landers 52 Explorer WISE 52 speckle pattern 52 ESO telescopes 52 cosmic microwave background 52 Radiometric 52 exosphere 52 multiwavelength 52 pointings 52 Milankovitch cycles 52 AU Mic 52 comets asteroids 52 Oort Cloud 52 Iapetus 52 Saturn moon Enceladus 52 Orbiter spacecraft 52 Lyman alpha 52 absorption spectra 52 infrared astronomy 52 Martian polar 52 thin crescent 52 circumstellar disk 52 visit http:/saturn.jpl.nasa.gov 52 ADM Aeolus 52 Kuiper belt object 52 Upsilon Andromedae b 52 NASA EPOXI mission 52 AERONET 52 Kepler Space Telescope 52 oxygen isotope 52 Extrasolar Planets 52 Albedo 52 radiometry 52 Churyumov Gerasimenko 52 Relations Observatory STEREO 52 UCO Lick 52 binary asteroid 52 HiRISE camera 52 cometary 52 radiative transfer 52 spectrometers 52 diffuse aurora 52 Gamma ray burst 52 hydroxyl molecules 52 protoplanet 52 Surface Stereo Imager 52 KamLAND 52 galactic cosmic rays 52 orbiter Cassini 52 infrared wavelength 52 SOHO spacecraft 52 Hellas Basin 52 Hubble Near Infrared 52 Rosette Nebula 52 inch Samuel Oschin 52 ESA Herschel 52 interstellar boundary 52 orbiting Chandra 52 Cassini spacecraft orbiting 52 NASA Kepler 52 mineral olivine 52 Earthlike 52 R Coronae Borealis 52 Cloud Aerosol Lidar 52 Saturnian moon Titan 52 Saturnian 52 BP Piscium 52 inch refractor telescope 52 Saturn outermost 52 Mars Odyssey orbiter 52 Ocean Salinity 52 optical wavelengths 52 NanoSIMS 51 comet nuclei 51 blackbody 51 polar mesospheric clouds 51 NEAR Shoemaker 51 Sinus Meridiani 51 Arabia Terra 51 moonlet 51 LAGEOS 51 Interferometer 51 NEAs 51 Keck Telescope 51 GRACE satellites 51 Saturn rings 51 Perseus Cluster 51 polar vortex 51 INMS 51 Pleiades cluster 51 Microscopy Electrochemistry 51 Spitzer Space Telescope 51 primitive meteorites 51 chemical abundances 51 Geminga 51 zodiacal light 51 antineutrinos 51 NASA rover Spirit 51 spectral fingerprint 51 weak gravitational lensing 51 UKIRT 51 WHIM 51 Higgs bosons 51 Epsilon Indi 51 millisecond pulsars 51 seismic tomography 51 HD# [002] 51 gradiometer 51 Gliese #g 51 http:/saturn.jpl.nasa.gov 51 aerosol particles 51 infrared spectrometer 51 chondritic meteorites 51 altimetry 51 occultation 51 Planck observatory 51 spaceweather.com 51 Kepler 9c 51 trench informally 51 Subaru telescope 51 spectroscope 51 Neogene 51 antihelium 4 51 distant quasar 51 Bonnie Buratti 51 Miniature Synthetic Aperture Radar 51 X ray pulses 51 planetary nebulas 51 Kuiper Belt Object 51 Galilean moons 51 NASA Landsat 51 MODIS 51 Taurus Littrow Valley 51 muon neutrino 51 slender crescent 51 Tropospheric Emission Spectrometer 51 SEGUE 51 Saturnian system 51 cosmic microwave radiation 51 exoplanets orbiting 51 lunar orbits 51 Foing 51 brightest supernova 51 comet Tempel Tuttle 51 Conductivity Analyzer MECA 51 aurorae 51 Imaging Spectroradiometer 51 George Djorgovski 51 Mars Phobos 51 multispectral imagery 51 hyperspectral imager 51 HARPS spectrograph attached 51 detect gravitational waves 51 astronomical objects 51 Andromeda halo 51 infrared wavelengths 51 Synthetic Aperture Radar 51 ESA Huygens probe 51 Lagrangian 51 Imaging Spectrometer MERIS 51 galaxy formation 51 GRBs 51 seabed sediments 51 SIM PlanetQuest 51 cryovolcanism 51 Surface Temperature 51 lensing galaxy 51 distant galaxies 51 planets orbits 51 Orion Nebula 51 Omega Centauri 51 Area Telescope LAT 51 enters lunar orbit 51 Earth orbiting satellites 51 gravitationally lensed 51 ultrashort pulses 51 Hinode 51 2MASS 51 AATSR 51 Multi Object Spectrometer 51 cosmic ray 51 Supernova #A 51 Infrared Pathfinder Satellite 51 BaBar experiment 51 Doppler measurements 51 supergiant star 51 Science Experiment HiRISE 51 ammonia hydrates 51 cometary material 51 Anthony Remijan 51 Photometric 51 planetary nebulae 51 gamma ray emission 51 Multi Object Spectrograph 51 detect gamma rays 51 Landsat satellites 51 Observatory STEREO 51 supersymmetric particles 51 NASA Voyager spacecraft 51 Bose Einstein Condensate 51 Auger Observatory 51 La Silla Chile 51 Mini Thermal Emission 51 O OREOS 51 SAXS 51 orbital eccentricity 51 High Resolution Imaging 51 GLAST telescope 51 Mastcam 51 NASA twin rovers 51 galactic mergers 51 COBE satellite 51 KH #D 51 inhabitable planets 51 irregularly shaped asteroid 51 Chang'eI 51 Ringed Planet 51 Saturn moon 51 Rayleigh scattering 51 geyser plumes 51 baryon acoustic oscillations 51 paleoclimate records 51 submillimeter wavelengths 51 astrophysical objects 51 magnetic monopoles 51 LROC 51 photoelectron spectroscopy 51 TGFs 51 transiting exoplanet 51 heavily cratered 51 Horsehead Nebula 51 NASA rovers 51 celestial sphere 51 Beta Pictoris b 51 exoplanet orbiting 51 axions 51 martian surface 51 Neptune Uranus 51 Geoscience Laser Altimeter 51 Saturn magnetosphere 51 Envisat satellites 51 Arecibo Observatory 51 constellation Hercules 51 Wolszczan 51 Suzaku X ray 51 planets circling 51 VIRTIS instrument 51 OSIRIS 51 Mojzsis 51 upper troposphere 51 Scatterometer 51 Kepler Telescope 51 accretion disks 51 P/# A2 51 SDSS telescope 51 Phoebe orbits 51 moons circling 51 Kepler spacecraft 51 astrophysical phenomena 51 type Ia supernova 51 Cassini Huygens Mission 51 Venusian atmosphere 51 DigitalGlobe WorldView 2 51 Martian lander 51 CDMS experiment 51 metallicity 51 Comet Hartley 51 GQ Lupi 51 Curiosity rover 51 polarimeter 51 GOSAT 51 supercomputer simulations 51 helium ions 51 Comet Hartley 2 51 radial velocities 51 Radiation Belt 51 asteroid Vesta 51 Borexino 51 CoRoT 7b 51 photoemission 51 Stephan Quintet 51 GLAST Burst Monitor 50 Hanny Voorwerp 50 coronal mass ejections CMEs 50 moon Charon 50 Cosmic Microwave Background CMB 50 Magellanic Stream 50 radiometric measurements 50 spectral fingerprints 50 Trapezium 50 exosolar planets 50 astronomical telescope 50 Nasa Mars Odyssey 50 globular cluster M# 50 Instrument OMI 50 planetary surfaces 50 fainter objects 50 planets Uranus 50 Earthlike planet 50 NASA satellites orbiting 50 starburst galaxy 50 Normalized Difference Vegetation 50 Aram Chaos 50 interferograms 50 lunar orbiting spacecraft 50 yardangs 50 Methone 50 ejecta plume 50 moon Io 50 SNfactory 50 Conductivity Analyzer 50 Super Earths 50 aerosol measurements 50 HiRISE 50 celestial objects 50 Eagle Nebula 50 ESA Cluster 50 lunar crater 50 subglacial lakes 50 Cassini Ion 50 Herschel Space Telescope 50 SHARAD 50 interstellar dust clouds 50 distant galaxy clusters 50 Planetary Fourier Spectrometer PFS 50 optical spectra 50 Viking Orbiter 50 smoothest flattest 50 HRTEM 50 comet Churyumov Gerasimenko 50 Gliese #d 50 HARPS instrument 50 reflection nebula 50 supermassive 50 Magnetosphere 50 abyssal plains 50 Microscopic Imager 50 sundog 50 elemental abundances 50 Swift Ultraviolet Optical 50 constellation Andromeda 50 Extreme Ultraviolet Imaging Spectrometer 50 Jupiter magnetosphere 50 Dynamics Observatory 50 ASPERA 50 oxygen isotopes 50 Candor Chasma 50 NASA twin STEREO 50 greatest insect emergences 50 particle detectors 50 Ocean Salinity SMOS 50 Rossby waves 50 Virgo Cluster 50 Lunar Module Eagle 50 photons particles 50 type Ia supernovae 50 Orionid meteors 50 graphite whiskers 50 Kuiper Belt object 50 WASP #b 50 isotope ratios 50 liquid ethane 50 bathymetry 50 cryosphere 50 Bose Einstein condensates 50 spectrometer readings 50 X ray Telescope XRT 50 submillimeter wavelength 50 accelerator mass spectrometry 50 AMIE camera 50 ejecta blanket 50 Martian 50 constellation Cetus 50 NuSTAR 50 stellar nurseries 50 extrasolar planets 50 magnetometry 50 helium atoms 50 cosmological observations 50 lander robotic arm 50 lunar perigee 50 Huygens lander 50 dwarf spheroidal galaxies 50 X ray spectroscopy 50 Banerdt