WASHINGTON — The U.S. Air Force Navigation Technology Satellite-3 — a flight experiment seven years in the making — is undergoing final tests ahead of a projected 2024 launch.
A lot is riding on this project. The $250 million experiment led by the Air Force Research Laboratory aims to deliver novel technologies for space-based positioning, navigation, and timing (PNT). It’s also seen as a test case for the management of the so-called PNT enterprise, which includes the satellites, the ground system and the receivers that allow users to talk to the satellites.
“In fiscal year 2024, we will launch and begin testing of the Navigation Technology Satellite 3, an end-to-end space-based prototype across space, ground, and user equipment segments to improve resiliency in contested environments against jamming and spoofing,” Frank Calvelli, assistant secretary of the Air Force for space acquisition and integration, said April 26 in testimony to the House Armed Services Committee’s strategic forces subcommittee.
In this case, “end to end” means the program is equally focused on the ground, space and user segments. The Air Force wants NTS-3 to serve as a model for how to avoid the problems experienced in the Global Positioning System program that for years has come under fire for the management of the ground segment and user equipment procurements.
The GPS next-generation ground system known as OCX was characterized by Calvelli as a “troubled program which is years late and significantly overrun on costs.”
Meanwhile, delays in the development of modern GPS receivers, according to the Government Accountability Office, have prevented military users from taking advantage of the more secure jam-resistant signals broadcast by GPS 3 satellites.
Calvelli has said that the problems experienced by GPS and other military satellites programs led him to write a list of “space acquisition tenets,” one of which is to “deliver ground before launch.”
NTS-3 will seek to demonstrate next-generation technologies not only in the satellite but also in the ground segment and signal-receiver devices, said Arlen Biersgreen, the NTS-3 program manager at AFRL.
Biersgreen in a recent interview said the satellite and ground control system are in the final integration and test campaign.
The project has garnered high-level attention, Biersgreen said. In the past several months he has briefed officials from the Air Force, Space Force and the Department of Transportation. Many of the questions he gets, Biersgreen added, are about the potential of NTS-3 to add a layer of resilience to the nation’s PNT capabilities.
Focus on space and ground
The satellite, built by L3Harris, will operate for one year in a near-geosynchronous orbit and will broadcast navigation signals from its phased array antenna, which can electronically steer signals to a desired region without physically moving the satellite.
Biersgreen said a digital reprogrammable PNT signal generator allows new signal updates after launch so it can counter interference. It also has new features designed to defeat spoofing.
The ground control system, developed by Parsons Corp., will be operated at AFRL Space Vehicles Directorate headquarters at Kirtland Air Force Base, New Mexico.
Ed Baron, senior vice president of Parsons’ space mission solutions, said compatibility testing with the satellite will be completed this summer.
Unlike other DoD space programs, the NTS-3 ground system development started before the satellite was built, Baron said. Parsons won the contract in 2017 and L3Harris received the satellite contract in 2018.
AFRL will use commercial ground antennas to increase opportunities for contact time with the satellite while reducing dependence on strained government antennas, Baron said.
Biersgreen said the software-defined radio technology used in the receivers will give operators on the ground access to NTS-3 and also GPS signals, as well as additional anti-jam and anti-spoof protections.
The technologies demonstrated in NTS-3 are expected to transition to military PNT satellites that could serve as backup to GPS.
Ensuring access to space-based PNT has become a growing priority since Russia’s invasion of Ukraine, where jammers were deployed by Russian forces to disrupt GPS signals. In addition to denying GPS through electronic jamming attacks, foreign militaries can also target U.S. military GPS users with falsified PNT data, a technique known as spoofing.
The Air Force designated NTS-3 as one of its so-called vanguard programs that promise to provide “superior advantages in the battlefield.”
“GPS is going to continue to be the gold standard, but we need to provide additional options,” Biersgreen said.
Launch date still uncertain
NTS-3 is scheduled for launch on USSF-106, a national security space mission assigned to United Launch Alliance’s Vulcan Centaur rocket. The 1,250-kilogram satellite will ride as a secondary payload.
That mission has been projected to launch in late 2023 but is likely to slip to 2024 due to delays caused by a Centaur upper stage anomaly that is still being investigated.
Vulcan has to complete two flights before it can be certified to fly USSF-106.
A spokesman for the U.S. Space Force Space Systems Command said the USSF-106 launch date “and any associated impacts due to the recent Centaur 5 test anomaly are currently under review. Any updates or new planning dates will be determined after the ULA investigation is complete.”
