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| Organization: | Department of the Navy |
| Major Contractors: | Naval Research Laboratory |
| Mission Type: | Earth Science |
| Satellite of: | Earth |
| Launch: | March 17, 1958 at 12:15:41 UTC |
| Launch Vehicle: | Vanguard rocket |
| Decay: | 240 year orbital lifetime |
| Mission Duration: | May, 1964 - ~2,200 days |
| Mass: | 1.47 kg |
| NSSDC ID: | 1958-002B |
| Webpage: | NASA NSSDC Master Catalog |
| Orbital elements | |
|---|---|
| Semimajor Axis: | 8,689.7 km |
| Eccentricity: | 0.1909 |
| Inclination: | 33.25° |
| Orbital Period: | 134.2 minutes |
| Apogee: | 3,969 km |
| Perigee: | 654 km |
| Orbits: | ~181,600 as of July 17, 2004 |
| Instruments | |
| Radio Beacon : | Tracking data used to map earth's shape |
| Satellite Drag : | Determine upper atmospheric densities |
| Thermistors : | Interior temperature |
Vanguard 1 is the oldest still orbiting artificial satellite, though there is no longer communication with it. It is a small earth-orbiting satellite that was designed to test the launch capabilities of a three-stage launch vehicle and the effects of the environment on a satellite and its systems in Earth orbit. It also was used to obtain geodetic measurements through orbit analysis.
The spacecraft was a 1.47 kg aluminum sphere 152 mm in diameter. It contained a 10 mW, 108 MHz mercury-battery powered transmitter and a 5 mW, 108.03 MHz transmitter powered by six solar cells mounted on the body of the satellite. Six short aerials protruded from the sphere. The transmitters were used primarily for engineering and tracking data, but were also used to determine the total electron content between the satellite and ground stations. Vanguard also carried two thermistors which measured the interior temperature over 16 days in order to track the effectiveness of the thermal protection.
The three stage launch vehicle placed Vanguard into a 654 x 3969 km 134.2 minute orbit inclined at 34.25 degrees on March 17, 1958. Original estimates had the orbit lasting for 2000 years, but it was discovered that solar radiation pressure and atmospheric drag during high levels of solar activity produced significant perturbations in the perigee height of the satellite, which caused a significant decrease in its expected lifetime to only about 240 years. The battery powered transmitter stopped operating in June 1958 when the batteries ran down. The solar powered transmitter operated until May 1964Events January January 1 Federation of Rhodesia and Nyasaland is dissolved. January 3 Senator Barry Goldwater announces that he will seek the Republican nomination for President. January 5 In the first meeting between leaders of the Roman Catholic and Ort (when the last signals were received in QuitoQuito is the capital city of Ecuador. Located in a valley on the western slopes of Pichincha, an active volcano in the Andes mountains, its elevation of around 2850 meters (9300 feet) above sea level makes it one of the world's highest capital cities., EcuadorThe Republic of Ecuador is a country of South America. Republica del Ecuador ( In Detail) National motto: Libertad y Orden ( Spanish; "The peace and wellbeing, the glory and triumph" Official language Spanish Capital Quito Largest City Guayaquil President) after which the spacecraft was optically tracked from Earth.