@prefix ns0: . @prefix skos: . ns0:altLabel [ ] ; skos:definition """The Atmospheric Explorer-D (AE-D) spacecraft (designation: 08353 / 75096A ) was designed as a multi- sided polyhedron shaped frame with a mean diameter of about 1.4 meters. AE-D was in most respects similar to AE-C. The AE-D was launched on 1975-10-6 and decayed 1976-03-12. The purpose of the AE-D mission was a direct continuation of the EA-C mission: to investigate the chemical and physical processes in the uppermost layer of the earth's atmosphere, the thermosphere, with emphasis on energy transfer and other controlling processes. Photochemical processes related to the absorption of solar UV radiation were studied by making coordinated measurements of reacting constituents and the solar input in the region of high absorption of solar energy. The payload included instrumentation to measure: Solar UV Fluxes, the Composition of Positive Ions and Neutral Particles, the Density and Temperature of neutral particles, positive ions and electrons, Atmospheric airglow emissions, Photoelectron Energy Spectra, and Proton and Electron Fluxes with particle energy up to 25 keV. This mission was planned to sample the high latitude regions at the same time that the AE-E mission was sampling the equatorial and low latitude regions. The same type of spacecraft as AE-C was used, and the payload consisted of the same types of instruments except for deletion of the extreme solar UV monitor and the Bennett ion mass spectrometer both of which were part of the AE-E payload. AE-D was placed in a high inclination (polar) orbit. The polar orbit provided sampling of all latitudes, the perigee moved through all latitudes in 3 months, and all local times in 4 months. Unfortunately, a failure in the solar power panels resulted in the termination of AE-D operations on January 29, 1976, after slightly less than 4 months of useful spacecraft life. However, all the regions at the perigee altitudes were sampled during this time. The AE-D spacecraft re-entered the earth's atmosphere about 1 month after the cessation of telemetry. To continue the correlated observations with the AE-E mission, the earlier AE-C spacecraft was then reactivated on February 28, 1976 as replacecment for AE-D. Power to AE-D was supplied by a solar cell array. The spacecraft used a PCM telemetry data system that operated in real time or using a tape recorder. Group: Platform_Details Entry_ID: AE-D Group: Platform_Identification Platform_Category: Earth Observation Satellites Platform_Series_or_Entity: AE (Atmosphere Explorer) Short_Name: AE-D Long_Name: Atmosphere Explorer D (Explorer 54) End_Group Group: Synonymous_Platform_Names Short_Name: Explorer 54 Short_Name: 08353 End_Group Group: Platform_Associated_Instruments Short_Name: MASS SPECTROMETERS End_Group Creation_Date: 2007-08-22 Online_Resource: http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1975-096A Group: Platform_Logistics Launch_Date: 1975-10-06 Primary_Sponsor: NASA End_Group End_Group"""@en ; skos:prefLabel "AE-D"@en ; skos:inScheme ; skos:broader ; a skos:Concept . skos:prefLabel "AE (Atmosphere Explorer)"@en ; a skos:Concept ; skos:narrower .