Global Positioning System supplies space-based military and civil radio-positioning for geolocation, navigation, and timing.

It is a fundamental enabler of precision bombing, CSAR, mapping, and rendezvous. It provides accurate and uninterrupted 3D (latitude, longitude, and altitude) position, velocity, and time data.

The last of the GPS Block IIA satellites, launched between 1990 and 1997 was decommissioned in 2020. GPS Block IIR and IIR-M (modernized) included 21 vehicles launched between 2005 and 2009.

Modernization upgrades included two new signals, enhanced encryption, anti-jamming capabilities, and a second civil signal. GPS Block IIF is a follow-on to IIR-M. Upgrades include extended design life, faster processors, and improved anti-jam and accuracy, a new military signal, and a second and third dedicated civil signal.

The GPS Block IIIA, first launched on Dec. 23, 2018, has improved accuracy, availability, integrity, and incorporates a steerable, high-power, anti-jam capability.

Lockheed Martin is under contract to build the final Block IIIA vehicles (nine and 10) for launch in 2022 and was awarded a follow-on $7.2 billion contract for 22 Block IIF in 2018. Block IIIF adds a hosted search and rescue payload, as well as geographically targetable high-power military signal and FY21 funds procurement of the second and third vehicles.

The third GPS III launch on June 30, 2020, marked the first GPS mission boosted by a SpaceX Falcon 9, and a fourth satellite successfully launched Nov. 5, 2020. Two GPS IIIA launches are slated for 2021 and the first IIIF is slated to be launch-ready by 2026.

Contractors: Boeing (IIF); Lockheed Martin (IIR, IIR-M, III/IIIF).
Operator/Location: USSF SpOC; Schriever SFB, Colo.
First Launch: Feb. 22, 1978.
IOC: Dec. 9, 1993.
Design Life: 7.5 yr (IIR/IIR-M); 12 yr (IIF); 15 yr (IIIA).
Launch Vehicle: Delta II, Delta IV, Falcon 9.
Constellation: 33 spacecraft (not including decommissioned or on-orbit spares).
Active Satellites: •GPS Block IIR. Launched 1997 to 2004; eight active. •GPS Block IIR-M. Launched in 2005 to 2009; seven active. •GPS Block IIF. Launched in 2010 to 2016; 12 active. •GPS Block IIIA/IIIF. New generation launched in 2018; three active.
Dimensions: (IIR/IIR-M) 5 x 6.3 x 6.25 ft, span incl solar panels 38 ft; (IIF) 9.6 x 6.5 x 12.9 ft, span incl solar panels 43.1 ft.
Weight: On orbit, 2,370 lb (IIR/IIR-M); 3,439 lb (IIF).
Performance: Orbits the Earth every 12 hr, emitting continuous signals, providing time to within one-millionth of a second, velocity within a fraction of a mile per hour, and location to within a few feet.
Orbit Altitude: 10,988 miles.
Power: Solar panels generating 1,136 watts (IIR/IIR-M); up to 2,900 watts (IIF).

More articles about the Global Positioning System