USA-91
USA-91, also known as GPS IIA-11, GPS II-20 and GPS SVN-37, was an American navigation satellite which formed part of the Global Positioning System. It was the eleventh of nineteen Block IIA GPS satellites to be launched.
| Mission type | Navigation |
|---|---|
| Operator | US Air Force |
| COSPAR ID | 1993-032A[1] |
| SATCAT no. | 22657[1] |
| Mission duration | 7.5 years (planned)[2] |
| Spacecraft properties | |
| Spacecraft type | GPS Block IIA[2] |
| Manufacturer | Rockwell[2] |
| Launch mass | 1,816 kilograms (4,004 lb)[2] |
| Start of mission | |
| Launch date | 13 May 1993, 00:07:00 UTC |
| Rocket | Delta II 7925-9.5, D220[3] |
| Launch site | Cape Canaveral LC-17A[3] |
| End of mission | |
| Disposal | Placed in a graveyard orbit |
| Deactivated | 18 March 2016 |
| Orbital parameters | |
| Reference system | Geocentric |
| Regime | Medium Earth (Semi-synchronous) |
| Perigee altitude | 20,033 kilometres (12,448 mi)[4] |
| Apogee altitude | 20,327 kilometres (12,631 mi)[4] |
| Inclination | 54.9 degrees[4] |
| Period | 717.88 minutes[4] |
USA-91 was launched at 00:07:00 UTC on 13 May 1993, atop a Delta II carrier rocket, flight number D220, flying in the 7925-9.5 configuration.[3] The launch took place from Launch Complex 17A at the Cape Canaveral Air Force Station,[5] and placed USA-91 into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-37XFP apogee motor.[2]
On 14 June 1993, USA-91 was in an orbit with a perigee of 20,033 kilometres (12,448 mi), an apogee of 20,327 kilometres (12,631 mi), a period of 717.88 minutes, and 54.9 degrees of inclination to the equator.[4] It broadcast signal PRN 07, and operated in slot 4 of plane C of the GPS constellation.[6] The satellite had a mass of 1,816 kilograms (4,004 lb). It had a design life of 7.5 years,[2] and ceased operations on 20 December 2007.
Following decommissioning, it was kept as a reserve satellite. It was finally put in a disposal orbit approximately 1000 km above the operational constellation on March 18, 2016.[7]
References
- "Navstar 2A-11". US National Space Science Data Center. Retrieved 10 July 2012.
- Krebs, Gunter. "GPS-2A (Navstar-2A)". Gunter's Space Page. 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.
- "50 SW to dispose of two GPS satellites". United States Air Force. Retrieved 21 March 2016.