USA-128
| Names | Navstar 2A-18 GPS IIA-18 GPS II-27 GPS SVN-30 |
|---|---|
| Mission type | Navigation |
| Operator | U.S. Air Force |
| COSPAR ID | 1996-056A |
| SATCAT no. | 24320 |
| Mission duration | 7.5 years (planned) 14.75 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 | 12 September 1996, 08:49:00 UTC |
| Rocket | Delta II 7925-9.5 (Delta D238) |
| Launch site | Cape Canaveral, LC-17A |
| Contractor | McDonnell Douglas |
| Entered service | 17 October 1996 |
| End of mission | |
| Disposal | Graveyard orbit |
| Deactivated | 20 July 2011 |
| Orbital parameters | |
| Reference system | Geocentric orbit |
| Regime | Medium Earth orbit (Semi-synchronous) |
| Slot | B2 (slot 2 plane B) |
| Perigee altitude | 20,058 km (12,463 mi) |
| Apogee altitude | 20,305 km (12,617 mi) |
| Inclination | 54.7° |
| Period | 717.94 minutes |
USA-128, also known as GPS IIA-18, GPS II-27 and GPS SVN-30, is an American navigation satellite which forms part of the Global Positioning System. It was the eighteenth of nineteen Block IIA GPS satellites to be launched.