GPS 2F-11, the Air Force’s penultimate GPS 2F series satellite is encapsulated inside an Atlas 5 4-meter payload fairing. Photo: ULA

[Via Satellite 02-01-2016] This week the U.S. Air Force, Boeing and United Launch Alliance (ULA) are planning to launch the final Global Positioning System (GPS) 2F series satellite, GPS 2F-12, in what marks not only the last 2F mission, but also the beginning of a busy year of National Security Satellite (NSS) launches. ULA is set to launch GPS 2F-12 on Feb. 5, following a brief delay to evaluate the electrical connectors on the Atlas 5 booster. The mission, according to Col. Steve Whitney, director of the U.S. Air Force’s Global Positioning Systems Directorate, caps off a 21-month stretch during which the U.S. launched seven GPS satellites. He described this period as one of the most aggressive launch campaigns in 20 years, but the Air Force is also looking forward to a packed launch schedule in 2016.

“We have a very busy national security space manifest with eight launches over the next nine months, beginning with this, the GPS 2F-12 mission,” Walter Lauderdale, GPS 2F-12 mission director, said during a Jan. 29 conference call. “This includes three pairs of launches where each pair is separated by a week or less. The first pair involves this launch and the Delta 4-NROL 45 launch on Feb. 10 from Vandenberg Air Force Base.”

Lauderdale said the two-day launch delay was the result of a possible concern with electrical connecters, which the GPS 2F-12 team then took the time to inspect. ULA Vice President of Custom Services Laura Maginnis said the connectors provide power as well as command and control to different components on the vehicle. Further details as to what prompted the concern over the integrity of the connecters were not disclosed.

The GPS 2F series brings improvements to the U.S. Global Navigation Satellite System (GNSS), such as better accuracy, longer design life and an additional signal for aviation and safety of life applications. Whitney said the series also include a more robust military signal, which, as of the Oct. 31 launch of GPS 2F-11, is now accessible from 18 satellites. He said this is significant because it allows the Air Force to have four satellites with this signal in view at all times anywhere in the world.

The GPS 2F satellites have also evolved since they were first introduced. Mark Smith, Boeing GPS 2F deputy program manager, said two of the satellites have an enhanced L1 capability that provides additional power to the users. Boeing has provided 50 GPS satellites to the U.S. government to date, including GPS 2F-12.

Currently, the U.S. Air Force has 30 satellites in the operational system for GPS. There are nine satellites kept in a residual status, with one recently relegated to this mode to make room for GPS 2F-12. The Air Force GPS system has the capacity to field a maximum operational constellation of 31 satellites.

Future GPS programs will have increased competition on both production and launch. On Jan. 8 the Air Force issued a Request for Proposals (RFP) for the GPS 3 Space Vehicles 11+ Phase 1 Production Readiness Feasibility Assessment contract. And companies are producing new products for future satellites. Harris Corporation recently announced that the company will begin offering fully digital payloads for GPS 3, up from the 70 percent digital payload used today, on Space Vehicles (SV) 11 and beyond. Lockheed Martin is building the first eight GPS 3 satellites, of which the first completed Thermal Vacuum (TVAC) testing in December 2015. The Air Force also issued an RFP in September 2015 for the launch of a GPS 3 satellite in 2018. ULA and SpaceX are certified to compete.

“The directorate here is currently engaged in a very aggressive campaign to modernize the GPS system across all three segments: space, ground and user equipment. The results of this campaign provide stronger signals, additional civil signals, and improve the robustness of the overall system architecture,” said Whitney.