| USA-206 | |
| Mission Type: | Navigation |
| Operator: | US Air Force |
| Cospar Id: | 2009-043A |
| Satcat: | 35752 |
| Mission Duration: | 10 years (planned) |
| Spacecraft Type: | GPS Block IIRM |
| Spacecraft Bus: | AS-4000 |
| Manufacturer: | Lockheed Martin |
| Launch Date: | UTC |
| Launch Rocket: | D343 |
| Launch Site: | Cape Canaveral SLC-17A |
| Launch Contractor: | ULA |
| Orbit Reference: | Geocentric |
| Orbit Regime: | Medium Earth (Semi-synchronous) |
| Orbit Periapsis: | 20200km (12,600miles) |
| Orbit Apoapsis: | 20200km (12,600miles) |
| Orbit Inclination: | 55 degrees |
| Orbit Period: | 12 hours |
| Apsis: | gee |
USA-206, also GPS SVN-50, PRN-05 and NAVSTAR 64 and known before launch as GPS IIR-21, GPS IIRM-8 or GPS IIR-21(M), is an American navigation satellite that forms part of the Navstar Global Positioning System. It was the twenty-first and last Block IIR GPS satellite to be launched and the eighth to use the modernized IIRM configuration.[1]
GPS IIR-21 was built by Lockheed Martin, based on the AS-4000 satellite bus, with the navigation payload being built by ITT.[1] It was launched by a United Launch Alliance Delta II rocket, using the 7925-9.5 configuration,[2] on 17 August 2009 at 10:35 GMT.[3] It was the last spacecraft to launch from Space Launch Complex 17A at the Cape Canaveral Air Force Station, a launch pad which was first used in August 1957 for test flights of the PGM-17 Thor missile.[4] It is also the final flight of an AS-4000 bus,[5] the final GPS launch on a Delta II, and the final Delta II launch to be overseen by the US Air Force.
Following separation from its carrier rocket, GPS IIR-21 received its USA designation, USA-206. It was deployed into a transfer orbit, from which raised itself to a semi-synchronous medium Earth orbit on 19 August, using an onboard Star 37FM apogee motor. It is a 2032kg (4,480lb) satellite,[6] and is expected to operate for at least ten years. Once it had completed on-orbit testing, it began covering Slot 3 of Plane E of the GPS constellation, replacing USA-126, or GPS IIA-26, which was launched in July 1996.[3] It was declared operational on 27 August 2009.[7]