@prefix ns0: . @prefix skos: . ns0:resource [ ] ; skos:definition """- Spacecraft Brief Description - Vanguard 2 was an earth-orbiting satellite designed to measure cloud-cover distribution over the daylight portion of its orbit. The spacecraft was a 9.8 kg magnesium sphere 50.8 cm in diameter. It contained two optical telescopes with two photocells. The sphere was internally gold-plated and externally covered with an aluminum deposit coated with silicon oxide of sufficient thickness to provide thermal control for the instrumentation. Radio communication was provided by a 1-W, 108.03-MHz telemetry transmitter and a 10-mW, 108-MHz beacon transmitter that sent a continuous signal for tracking purposes. A command receiver was used to activate a tape recorder that relayed telescope experiment data to the telemetry transmitter. Both transmitters functioned normally for 19 days. The satellite was spin stabilized at 50 rpm, but telemetry data were poor because of an unsatisfactory orientation of the spin axis. The power supply for the instrumentation was provided by mercury batteries. - Auxiliary Information - Launch Date and Time : 1959-02-17 16:05:00 Epoch Date and Time : 1959-02-17 16:48:00 Apogee (km or AU): 3320. Perigee (km or AU): 559. Inclination (degree) : 32.88 Orbit Type : Geocentric Information last updated on 1992-04-14 Vanguard 3 was launched by a Vanguard rocket from the Eastern Test Range into a geocentric orbit. The objectives of the flight were to measure the earth's magnetic field, the solar X-ray radiation and its effects on the earth's atmosphere, and the near-earth micrometeoroid environment. Instrumentation included a proton magnetometer, X-ray ionization chambers, and various micrometeoroid detectors. The spacecraft was a 50.8-cm-diameter magnesium sphere. The magnetometer was housed in a glass fiber phenolic resin conical tube attached to the sphere. Data transmission stopped on December 11, 1959, after 84 days of operation. The data obtained provided a comprehensive survey of the earth's magnetic field over the area covered, defined the lower edge of the Van Allen radiation belt, and provided a count of micrometeoroid impacts. Vanguard 3 has an expected orbital lifetime of 300 yr. - Auxiliary Information - Launch Date and Time : 1959-09-18 05:16:00 Epoch Date and Time : 1959-09-18 14:24:00 Apogee (km or AU): 3744. Perigee (km or AU): 512. Inclination (degree) : 33.3 Orbit Type : Geocentric Information last updated on 1992-04-14 Group: Platform_Details Entry_ID: VANGUARD Group: Platform_Identification Platform_Category: Earth Observation Satellites Short_Name: VANGUARD End_Group Group: Synonymous_Platform_Names Short_Name: VANGUARD End_Group Creation_Date: 2007-11-30 Online_Resource: http://history.nasa.gov/SP-4202/toc2.html Sample_Image: http://history.nasa.gov/SP-4202/p0-ii.jpg Group: Platform_Logistics Launch_Date: 1959-02-17 Primary_Sponsor: United States Department of Defense End_Group End_Group"""@en ; skos:prefLabel "VANGUARD"@en ; skos:inScheme ; skos:broader ; a skos:Concept . skos:prefLabel "Earth Observation Satellites"@en ; a skos:Concept ; skos:narrower .