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Artist's impression of a GPS IIRM satellite in orbit
Mission typeNavigation
OperatorUS Air Force
COSPAR ID2009-043A
SATCAT no.35752
Mission duration10 years (planned)
Spacecraft properties
Spacecraft typeGPS Block IIRM
ManufacturerLockheed Martin
Launch mass2,032 kilograms (4,480 lb)
Start of mission
Launch date17 August 2009, 10:35:00 (2009-08-17UTC10:35Z) UTC
RocketDelta II 7925-9.5, D343
Launch siteCape Canaveral SLC-17A
Orbital parameters
Reference systemGeocentric
RegimeMedium Earth
Perigee altitude20,200 kilometres (12,600 mi)
Apogee altitude20,200 kilometres (12,600 mi)
Inclination55 degrees
Period12 hours

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 modernised IIRM configuration.[2]

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]


  1. ^ a b Krebs, Gunter. "Navstar 2RM". Gunter's Space Page. Retrieved 15 August 2009.
  2. ^ a b "Final LockMart Modernized GPS IIR Satellite Set For Launch". GPS Daily. 11 August 2009. Retrieved 15 August 2009.
  3. ^ a b c "Delta II GPS IIR-21 Mission Booklet" (PDF). United Launch Alliance. Retrieved 5 July 2020.
  4. ^ a b Ray, Justin. "Mission Status Center". Delta Launch Report. Spaceflight Now. Retrieved 15 August 2009.
  5. ^ Ray, Justin (24 March 2009). "Delta 2 rocket delivers another GPS satellite to orbit". Spaceflight Now. Retrieved 13 August 2009.
  6. ^ Krebs, Gunter. "Martin Marietta -> Lockheed Martin: 4000". Gunter's Space Page. Retrieved 15 August 2009.
  7. ^ "Air Force Sets Latest GPS Satellite Operational". Inside GNSS. 27 August 2009. Archived from the original on 6 December 2010. Retrieved 6 September 2009.
This page was last edited on 18 December 2020, at 08:16
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