On 17 February 1959, the United States successfully launched the Vanguard 2 satellite from Cape Canaveral. It was designed to measure cloud cover distribution, thus making it the first weather satellite.
The satellite was a 20-inch diameter sphere, weighing 23.7 pounds. It was spin stabilized, but wobbled so as to degrade the cloud cover data. The 1-watt data transmitter worked for 23 days, and the 10-milliwatt tracking beacon lasted 26 days. The short mission was as anticipated, due to battery lifetime. It was more a proof of concept mission than anything else, and it certainly did that.
Both Vanguard 2, and the upper stage of its launch rocket are still in orbit, and should remain there for about 300 years, before the drag of the tenuous atmosphere at that height finally brings it down. Careful monitoring of the motion of the satellite continues to probe the density of the upper atmosphere, thus continuing the 300-year scientific mission for Vanguard 2.
The United States alone now has somewhere between 20 & 30 active weather satellites. There are numerous weather & Earth observing satellites up there now, in equatorial, polar, geosynchronous & geostationary orbits. Believe it or not, weather predictions are now far more reliable than they were, specifically due to the wealth of information returned by weather satellites.
The era of weather & Earth observing satellites, one of which I worked on (Terra/ASTER), all started with Vanguard 2. The ASTER instrument on Terra is an Earth surface observer, not a weather satellite, but I worked as an atmospheric scientist on the science team.
https://en.wikipedia.org/wiki/Vanguard_2 (Wikipedia)
https://www.youtube.com/watch?v=mgyhlQiKhhE (1m 25s historic video of Vanguard 2 & launch)
https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action... (NASA Space Science Data Coordinated Archive; image source)
https://www.heavens-above.com/SatInfo.aspx?satid=11&lat=0... (Vanguard 2 - Heavens Above)
https://www.heavens-above.com/orbit.aspx?satid=00011 (Vanguard 2, orbit & ground track - Heavens Above)
https://www.n2yo.com/satellite/?s=11 (Live tracking of Vanguard 2 - N2YO.com)
https://en.wikipedia.org/wiki/Weather_satellite (Weather satellite)
https://www.ssd.noaa.gov/imagery/index.html (NOAA Satellite and Information Service)
ASTER Algorithm Theoretical Basis Documents. I co-authored “Atmospheric Correction Method for ASTER Thermal Radiometry Over Land” (ATBD-AST-09T; 15 February 1999)
“EOS ASTER thermal infrared band vicarious calibration” (proceedings of the SPIE, December 2001)
Originally posted by Tim Thompson, NASA JPL Senior Astronomer (Retired)
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