USA-66
| Names | Navstar 2A-01 GPS IIA-1 GPS II-10 GPS SVN-23 |
|---|---|
| Mission type | Navigation |
| Operator | U.S. Air Force |
| COSPAR ID | 1990-103A |
| SATCAT no. | 20959 |
| Mission duration | 7.5 years (planned) 25 years (achieved) |
| Spacecraft properties | |
| Spacecraft | GPS IIA |
| Spacecraft type | GPS Block IIA |
| Manufacturer | Rockwell International |
| Launch mass | 840 kg (1,850 lb) |
| Dimensions | 5.3 m (17 ft) of long |
| Power | 710 watts |
| Start of mission | |
| Launch date | 26 November 1990, 21:39:01 UTC |
| Rocket | Delta II 7925-9.5 (Delta D201) |
| Launch site | Cape Canaveral, LC-17A |
| Contractor | McDonnell Douglas |
| Entered service | 30 December 1990 |
| End of mission | |
| Disposal | Graveyard orbit |
| Deactivated | 25 January 2016 |
| Orbital parameters | |
| Reference system | Geocentric orbit |
| Regime | Medium Earth orbit (Semi-synchronous) |
| Slot | E5 (slot 5 plane E) |
| Perigee altitude | 19,935 km (12,387 mi) |
| Apogee altitude | 20,279 km (12,601 mi) |
| Inclination | 54.8° |
| Period | 714.8 minutes |
USA-66, also known as GPS IIA-1, GPS II-10 and GPS SVN-23, was an American navigation satellite which formed part of the Global Positioning System. It was the first of nineteen Block IIA GPS satellites to be launched, and was the oldest GPS satellite still in operation until its decommissioning on 25 January 2016.