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.[2] 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.

GPS Block IIF
Artist's impression of a Block IIF GPS satellite in orbit
ManufacturerBoeing
Country of origin United States
OperatorUnited States Air Force
ApplicationsSatellite navigation
Specifications
BusAS-4000
Design life12 years
Launch mass1,633 kilograms (3,600 lb)[1]
Power1952 W (end of life)[1]
RegimeSemi-synchronous MEO
Dimensions
Production
StatusProduction Completed
Built12
On order0
Launched12
Operational12
Maiden launchGPS IIF SV-1
28 May 2010, 03:00 UTC
Last launchGPS IIF-12
5 February 2016, 13:38 UTC
← GPS Block IIR GPS Block IIIA →

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.[3] The final satellite of the Block IIA series was decommissioned on January 25, 2016.[4] 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.[5]

New characteristics
  • Broadcasting L5 "safety of life" navigation signal demonstrated on USA-203[3]
  • Broadcasting a new M-code signal[3]
  • Doubling in the predicted accuracy[6]
  • Better resistance to jamming[3]
  • Reprogrammable processors that can receive software uploads[3]
  • The first GPS satellites not to have Selective Availability (SA) hardware installed, which degraded civilian accuracy when turned on in the original satellite fleet[3]

Launch history

Overall, 12 GPS Block IIF satellites were launched, all of which are currently operational.

GPS Block IIF satellites
Satellite USA designation Launch Date
(UTC)		 Rocket Launch Site Status Notes Ref.
GPS IIF-1 USA-213 28 May 2010, 03:00 Delta IV-M+(4,2), D349 Cape Canaveral SLC-37B In Service [6][7][8]
GPS IIF-2 USA-232 16 July 2011, 06:41 Delta IV-M+(4,2), D355 Cape Canaveral SLC-37B In Service [9]
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. [10]
GPS IIF-4 USA-242 15 May 2013, 21:38 Atlas V 401, AV-039 Cape Canaveral SLC-41 In Service [11][12]
GPS IIF-5 USA-248 25 February 2014, 01:59 Delta IV-M+(4,2), D365 Cape Canaveral SLC-37B In Service [13]
GPS IIF-6 USA-251 17 May 2014, 00:03 Delta IV-M+(4,2), D366 Cape Canaveral SLC-37B In Service [14]
GPS IIF-7 USA-256 2 August 2014, 03:23 Atlas V 401, AV-048 Cape Canaveral SLC-41 In Service [15][16]
GPS IIF-8 USA-258 29 October 2014, 17:21 Atlas V 401, AV-050 Cape Canaveral SLC-41 In Service [17][18]
GPS IIF-9 USA-260 25 March 2015, 18:36 Delta IV-M+(4,2), D371 Cape Canaveral SLC-37B In Service [19]
GPS IIF-10 USA-262 15 July 2015, 15:36 Atlas V 401, AV-055 Cape Canaveral SLC-41 In Service [15]
GPS IIF-11 USA-265 31 October 2015, 16:13 Atlas V 401, AV-060 Cape Canaveral SLC-41 In Service [15][20]
GPS IIF-12 USA-266 5 February 2016, 13:38 Atlas V 401, AV-057 Cape Canaveral SLC-41 In Service [15][21]
gollark: Suuuuuuuuure.
gollark: This sort of thing seems like more of a vague moral signalling statement than actual advice.
gollark: This is significantly nonaesthetic.
gollark: It begins.
gollark: I dislike rounded corners, see.

See also

References
  1. "Global Positioning System". Boeing. Retrieved May 6, 2016.
  2. "Global Positioning System (GPS) IIF". Boeing. Retrieved May 27, 2010.
  3. "First Block 2F GPS Satellite Launched, Needed to Prevent System Failure". DailyTech. Archived from the original on May 30, 2010. Retrieved May 30, 2010.
  4. "GPS CONSTELLATION STATUS". U.S. Coast Guard Navigation Center. Retrieved January 25, 2016.
  5. Pike, John. "GPS Block II F". Globalsecurity.org. Retrieved May 27, 2010.
  6. "Mission Overview" (PDF). Delta IV Launches GPS IIF SV-1. United Launch Alliance. May 28, 2010. Retrieved October 29, 2015.
  7. Tariq Malik (May 28, 2010). "Air Force Launches Advanced New GPS Satellite". SPACE.com.
  8. "ULA Marks Delta 50th Anniversary with Successful Delta IV GPS IIF SV-1 Launch". United Launch Alliance. May 28, 2010. Retrieved October 29, 2015.
  9. "United Launch Alliance Marks the 50th Successful GPS Launch for the Air Force with the Delivery of the GPS IIF-2 Mission to Orbit". United Launch Alliance. July 16, 2011. Retrieved October 29, 2015.
  10. "United Launch Alliance GPS IIF-3". United Launch Alliance. Archived from the original on October 1, 2012. Retrieved October 8, 2012.
  11. "ULA Atlas V sets sail with new GPS satellite". NASA Space Flight. May 15, 2013. Retrieved May 15, 2013.
  12. "Orbit Data and Resources on Active GNSS Satellites". GPS World. Retrieved March 6, 2014.
  13. "United Launch Alliance Successfully Launches 25th Delta IV Mission Carrying Global Positioning System Satellite for the U.S. Air Force". United Launch Alliance. Archived from the original on February 9, 2014. Retrieved March 6, 2014.
  14. "Sixth GPS IIF Spacecraft Launches". Inside GNSS. Gibbons Media & Research LLC. May 17, 2014.
  15. "Boeing Satellite Launch Schedule". Boeing. Archived from the original on June 11, 2014. Retrieved May 17, 2014.
  16. "Atlas V to Launch GPS IIF-7". United Launch Alliance. Retrieved August 2, 2014.
  17. "Atlas V successfully vaults satellite to orbit". Florida Today. August 2, 2014. Retrieved October 29, 2015.
  18. "NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2014090". United States Coast Guard. December 12, 2014. Retrieved October 29, 2015.
  19. "United Launch Alliance GPS IIF-9" (PDF). Retrieved March 25, 2015.
  20. "Atlas V to Launch GPS IIF-11". October 31, 2015. Retrieved October 31, 2015.
  21. "New GPS satellite begins transmitting to users around the globe". Retrieved March 9, 2016.
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