|Operator||US Air Force|
|Mission duration||7.5 years (planned)|
|Spacecraft type||GPS Block II|
|Launch mass||840 kilograms (1,850 lb)|
|Start of mission|
|Launch date||21 October 1989, 09:31:01UTC|
|Rocket||Delta II 6925, D188|
|Launch site||Cape Canaveral LC-17A|
|End of mission|
|Deactivated||11 September 2001|
|Perigee altitude||20,081 kilometres (12,478 mi)|
|Apogee altitude||20,280 kilometres (12,600 mi)|
USA-47, also known as GPS II-4 and GPS SVN-19, was an American navigation satellite which formed part of the Global Positioning System. It was the fourth of nine Block II GPS satellites to be launched, which were the first operational GPS satellites to fly.
USA-47 was launched at 09:31:01 UTC on 21 October 1989, atop a Delta II carrier rocket, flight number D188, flying in the 6925 configuration. The launch took place from Launch Complex 17A at the Cape Canaveral Air Force Station, and placed USA-47 into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-37XFP apogee motor.
On 21 November 1989, USA-47 was in an orbit with a perigee of 20,081 kilometres (12,478 mi), an apogee of 20,280 kilometres (12,600 mi), a period of 717.9 minutes, and 54.7 degrees of inclination to the equator. It operated in slot 5 of plane A of the GPS constellation. The satellite had a mass of 840 kilograms (1,850 lb), and generated 710 watts of power. It had a design life of 7.5 years, and ceased operations on 11 September 2001.
- Krebs, Gunter. "GPS-2 (Navstar-2)". Gunter's Space Page. Retrieved 10 July 2012.
- "Navstar 2-04". US National Space Science Data Center. Retrieved 10 July 2012.
- McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 10 July 2012.
- McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. Retrieved 10 July 2012.
- McDowell, Jonathan. "Launch List". Launch Vehicle Database. Jonathan's Space Page. Retrieved 10 July 2012.
- Wade, Mark. "Navstar". Encyclopedia Astronautica. Retrieved 10 July 2012.
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