EntityQ49897· pop 10· linked from 179 articlesExplorer 9Sign in to saveAmerican satelliteConnectionsExplorers ProgramEntitydensity of airEntitynitrogenEntityNASAConceptlatitudeEntitypublic domainEntitydigital object identifierEntityInternational Standard Serial NumberEntityCambridgeEntityGreenwich Mean TimeEntitysolar cellEntityionosphereEntityorbital periodEntitymesosphereEntitythermosphereEntityapsisEntityexosphereEntitySmithsonian InstitutionEntityVostok 1EntitybibcodeEntityCategoriesBalloon satellitesExplorers ProgramGeospace monitoring satellitesPassive satellitesSatellites in medium Earth orbitSource attributionSpacecraft launched in 1961Spacecraft which reentered in 1964