GPS Block IIF, or GPS IIF is an interim class of
GPS (satellite)
GPS satellite blocks are the various production generations of the Global Positioning System (GPS) used for satellite navigation. The first satellite in the system, Navstar 1, was launched on 22 February 1978. The GPS satellite constellatio ...
, 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 sy ...
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 Sat ...
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 product ...
, 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 Signal ...
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 ...
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 geocentric orbit, 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 planets ...
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
A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propulsive jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, produ ...
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
USA-203, also known as GPS IIR-20(M), GPS IIRM-7 and GPS SVN-49, is an American navigation satellite which was intended to become part of the Global Positioning System. It was the sixth of seven Block IIRM satellites to be launched, and the twenti ...
* 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:
See also
*
BeiDou Navigation Satellite System
The BeiDou Navigation Satellite System (BDS; ) is a Chinese satellite navigation system. It consists of two separate satellite constellations. The first BeiDou system, officially called the BeiDou Satellite Navigation Experimental System and ...
*
BeiDou-2 (COMPASS) navigation system
*
Galileo (satellite navigation)
Galileo is a global navigation satellite system (GNSS) that went live in 2016, created by the European Union through the European Space Agency (ESA), operated by the European Union Agency for the Space Programme (EUSPA), headquartered in Pra ...
*
GLONASS
GLONASS (russian: ГЛОНАСС, label=none, ; rus, links=no, Глобальная навигационная спутниковая система, r=Global'naya Navigatsionnaya Sputnikovaya Sistema, t=Global Navigation Satellite System) is ...
*
Quasi-Zenith Satellite System
The Quasi-Zenith Satellite System (QZSS), also known as , is a four-satellite regional time transfer system and a satellite-based augmentation system developed by the Japanese government to enhance the United States-operated Global Positioni ...
References
{{GPS satellites
Global Positioning System