WASHINGTON — The U.S. Space Force has yet to launch all of the GPS III satellites at its disposal, but work on new, more powerful versions is already underway. New GPS III Follow-on satellites — or GPS IIIF for short — will continue to improve the constellation’s accuracy and protection against jamming.
GPS III satellites are already a substantial upgrade to the current constellation, providing three times greater accuracy and eight times better anti-jamming capability than their predecessors. In addition to introducing a new civil signal that is compatible with other navigation satellite systems, the five GPS III satellites on orbit completed the space component of M-code — an even more secure and accurate signal for military use.
The Space Force has launched five of the planned GPS III satellites, and three more have been declared “available for launch” but are waiting in storage with prime contractor Lockheed Martin. The remaining two are undergoing testing.
The Space Force has a contract with Lockheed for up to 22 GPS IIIF satellites. The service already exercised contract options for seven GPS IIIF satellites, with the most recent award taking place in October 2021, when Space Systems Command issued $737 million to the company for three more satellites.
GPS IIIF satellites will be more advanced than their predecessors. Most notably, the new space systems will prove a new Regional Military Protection capability, a steerable M-code signal that can concentrate the effect in a specified region. RMP can provide up to 60 times greater anti-jamming measures, helping ensure soldiers can access critical position, navigation and timing data in contested environments.
Other new features include a laser retroreflector array to increase accuracy; an upgraded nuclear detection detonation system payload; and a search and rescue payload.
Starting with the third GPS IIIF space vehicle, the satellites will be built with Lockheed’s LM2100 Combat Bus, specifically designed for military use. The company claims its new bus, which will also be used for the Space Force’s next missile warning satellites, will have greater resiliency and cyber protections, more power, and better propulsion.
And thanks to a new port option on the LM2100 bus, it could be possible to upgrade GPS IIIF satellites on orbit. The company’s Augmentation System Port Interface essentially works as a USB port for the satellite, allowing the Space Force to launch new payloads into space that can be plugged into the system.
Nathan Strout covers space, unmanned and intelligence systems for C4ISRNET.
