GPS Block IIF
GPS Block IIF, or GPS IIF is an interim class of GPS (satellite), which are used to keep the Navstar Global Positioning System operational until the GPS Block IIIA satellites become operational. They are being built by Boeing, and will be operated by the United States Air Force following their launch by United Launch Alliance, using Evolved Expendable Launch Vehicles. They are the final component of the Block II GPS constellation to be launched. On February 5, 2016, the final satellite in the IIF-block was successfully launched, completing the block.
Artist's impression of a Block IIF GPS satellite in orbit
|Country of origin||United States|
|Operator||United States Air Force|
|Design life||12 years|
|Launch mass||1,633 kilograms (3,600 lb)|
|Power||1952 W (end of life)|
|First launch||GPS IIF SV-1|
28 May 2010, 03:00 UTC
|Last launch||GPS IIF-12|
5 February 2016, 13:38 UTC
The spacecraft have a mass of 1,630 kilograms (3,590 lb) and a design life of 12 years. Like earlier GPS satellites, Block IIF spacecraft operate in semi-synchronous medium Earth orbits, with an altitude of approximately 20,460 kilometers (12,710 mi), and an orbital period of twelve hours.
The satellites replace the GPS Block IIA satellites that were launched between 1990 and 1997 and were designed to last 7.5 years. The final satellite of the Block IIA series was decommissioned on January 25, 2016. The operational constellation now includes Block IIR, IIRM and IIF variants.
Because the Evolved Expendable Launch Vehicles are more powerful than the Delta II, which was used to orbit earlier Block II GPS satellites, they can place the satellites directly into their operational orbits. As a result, Block IIF satellites do not carry apogee kick motors. The original contract for Block IIF, signed in 1996, called for 33 spacecraft. This was later reduced to 12, and program delays and technical problems pushed the first launch from 2006 to 2010.
- Broadcasting L5 "safety of life" navigation signal demonstrated on USA-203
- Broadcasting a new M-code signal
- Doubling in the predicted accuracy
- Better resistance to jamming
- Reprogrammable processors that can receive software uploads
- The first GPS satellites not to have Selective Availability (SA) hardware installed, which degraded civilian accuracy when turned on in the original satellite fleet
Overall, 12 GPS Block IIF satellites were launched, all of which are currently operational.
|Satellite||USA designation||Launch Date
|GPS IIF-1||USA-213||28 May 2010, 03:00||Delta IV-M+(4,2), D349||Cape Canaveral SLC-37B||In Service|||
|GPS IIF-2||USA-232||16 July 2011, 06:41||Delta IV-M+(4,2), D355||Cape Canaveral SLC-37B||In Service|||
|GPS IIF-3||USA-239||4 October 2012, 12:10||Delta IV-M+(4,2), D361||Cape Canaveral SLC-37B||In Service||This launch came shortly before the 10th anniversary of the inaugural Delta IV launch.|||
|GPS IIF-4||USA-242||15 May 2013, 21:38||Atlas V 401, AV-039||Cape Canaveral SLC-41||In Service|||
|GPS IIF-5||USA-248||25 February 2014, 01:59||Delta IV-M+(4,2), D365||Cape Canaveral SLC-37B||In Service|||
|GPS IIF-6||USA-251||17 May 2014, 00:03||Delta IV-M+(4,2), D366||Cape Canaveral SLC-37B||In Service|||
|GPS IIF-7||USA-256||2 August 2014, 03:23||Atlas V 401, AV-048||Cape Canaveral SLC-41||In Service|||
|GPS IIF-8||USA-258||29 October 2014, 17:21||Atlas V 401, AV-050||Cape Canaveral SLC-41||In Service|||
|GPS IIF-9||USA-260||25 March 2015, 18:36||Delta IV-M+(4,2), D371||Cape Canaveral SLC-37B||In Service|||
|GPS IIF-10||USA-262||15 July 2015, 15:36||Atlas V 401, AV-055||Cape Canaveral SLC-41||In Service|||
|GPS IIF-11||USA-265||31 October 2015, 16:13||Atlas V 401, AV-060||Cape Canaveral SLC-41||In Service|||
|GPS IIF-12||USA-266||5 February 2016, 13:38||Atlas V 401, AV-057||Cape Canaveral SLC-41||In Service|||
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