USA-206,[1] 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 which 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.[2]

USA-206

Artist's impression of a GPS IIRM satellite in orbit
Mission type	Navigation
Operator	US Air Force
COSPAR ID	2009-043A
SATCAT no.	35752
Mission duration	10 years (planned)
Spacecraft properties
Spacecraft type	GPS Block IIRM
Bus	AS-4000
Manufacturer	Lockheed Martin
Launch mass	2,032 kilograms (4,480 lb)
Start of mission
Launch date	17 August 2009, 10:35:00 (2009-08-17UTC10:35Z) UTC
Rocket	Delta II 7925-9.5, D343
Launch site	Cape Canaveral SLC-17A
Contractor	ULA
Orbital parameters
Reference system	Geocentric
Regime	Medium Earth (Semi-synchronous)
Perigee altitude	20,200 kilometers (12,600 mi)
Apogee altitude	20,200 kilometers (12,600 mi)
Inclination	55 degrees
Period	12 hours

GPS IIR-21 was built by Lockheed Martin, based on the AS-4000 satellite bus, with the navigation payload being built by ITT.[2] It was launched by a United Launch Alliance Delta II rocket, using the 7925-9.5 configuration,[3] on 17 August 2009 at 10:35 GMT.[4] 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.[5] It is also the final flight of an AS-4000 bus,[6] the final GPS launch on a Delta II, and the final Delta II launch to be overseen by the US Air Force.[3]

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 2,032-kilogram (4,480 lb) satellite,[1] and is expected to operate for at least ten years.[3] 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.[4] It was declared operational on 27 August 2009.[7]

References