GPS Block IIF, or GPS IIF is an interim class of GPS (satellite), which are used to keep the Navstar

Global Positioning System The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite ...

operational until the

GPS Block IIIA GPS Block III (previously Block IIIA) consists of the first ten GPS III satellites, which will be used to keep the Navstar Global Positioning System operational. Lockheed Martin designed, developed and manufactured the GPS III Non-Flight Sate ...

satellites become operational. They were built by

Boeing The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and ...

, to be operated by the

United States Air Force The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Si ...

being launched by

United Launch Alliance United Launch Alliance (ULA), legally United Launch Alliance, LLC, is an American spacecraft launch service provider that manufactures and operates a number of rocket vehicles that are capable of launching spacecraft into orbits around Earth, a ...

(ULA), using

Evolved Expendable Launch Vehicle National Security Space Launch (NSSL) — formerly Evolved Expendable Launch Vehicle (EELV) from 1994 to 2019 — is a program of the United States Space Force (USSF) intended to assure access to space for United States Department of Defense and o ...

s (EELV). They are the final component of the Block II GPS constellation to be launched. On 5 February 2016, the final satellite in the GPS Block IIF was successfully launched, completing the block. The spacecraft have a mass of and a design life of 12 years. Like earlier GPS satellites, Block IIF spacecraft operate in semi-synchronous

medium Earth orbit A medium Earth orbit (MEO) is an Earth-centered orbit with an altitude above a low Earth orbit (LEO) and below a high Earth orbit (HEO) – between above sea level.

s, with an altitude of approximately , and an

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting pla ...

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 25 January 2016. The operational constellation now includes Block IIR, IIRM, IIF and III variants. Because the Evolved Expendable Launch Vehicles are more powerful than the

Delta II Delta II was an expendable launch system, originally designed and built by McDonnell Douglas. Delta II was part of the Delta rocket family and entered service in 1989. Delta II vehicles included the Delta 6000, and the two later Delta 7000 va ...

, 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 motor An apogee kick motor (AKM) is a rocket motor that is regularly employed on artificial satellites to provide the final impulse to change the trajectory from the transfer orbit into its final (most commonly circular) orbit. For a satellite la ...

s. 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.

New characteristics

* 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 The error analysis for the Global Positioning System is important for understanding how GPS works, and for knowing what magnitude of error should be expected. The GPS makes corrections for receiver clock errors and other effects but there are sti ...

(SA) hardware installed, which degraded civilian accuracy when turned on in the original satellite fleet

Launch history

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

References

{{GPS satellites Global Positioning System

New characteristics

Launch history

See also

References