WASHINGTON — Northrop Grumman has delivered a bus for Navigation Technology Satellite-3 (NTS-3), ensuring that the experimental positioning satellite is on track for launch in 2023.
As one of the Air Force Research Laboratory’s four Vanguard programs — initiatives that are expected to deliver transformational technologies to the war fighter — NTS-3 is being developed to demonstrate new positioning, navigation and timing capabilities that could improve GPS satellites in the future. For example, the experimental satellite will feature steerable beams for regional coverage and a reprogrammable software-defined payload that can be updated on orbit. While the satellite won’t impact the GPS satellites expected to launch in the next few years, it could lead to improvements in the GPS IIIF satellites, such as space vehicles 14, 15 and 16 which will go on orbit in the late 2020s.
In addition to demonstrating technology for future GPS satellites, NTS-3 will augment the current GPS constellation while on orbit, supporting war fighters with an additional PNT signal from geostationary orbit. AFRL expects to conduct tests with the satellite for one year before transferring it to the U.S. Space Force, which then will integrate it with its PNT capabilities.
AFRL awarded L3Harris an $84 million contract in 2018 to act as prime contractor on the satellite and develop the payload. The government cleared the satellite for fabrication in August 2020 after it passed a critical design review.
Now, AFRL says Northrop Grumman has delivered the ESPAStar-D spacecraft bus that will host the experimental payload.
“The transfer of the bus allows L3Harris to move forward building the NTS-3 spacecraft,” NTS-3 Deputy Principal Investigator 2nd Lt. Charles Schramka said in a June 24 statement. “L3Harris will perform tests and begin integrating the NTS-3 PNT payload onto the bus. Together the bus and payload will form the NTS-3 spacecraft.”
In its statement, AFRL highlighted the fact that it’s using a commercial bus for NTS-3, a growing trend in government satellite acquisitions. The ESPAStar bus includes communications, power and control subsystems with standard interfaces for simple payload integration. It also features an AFRL-developed Expendable Launch Vehicle (EELV) Secondary Payload Adapter (ESPA) ring, which enables manufacturers to stack multiple payloads on one launch vehicle.
“This is the first time an ESPAStar-D bus has been built and delivered as a commercially-available commodity,” said Arlen Biersgreen, the NTS-3 program manager. “NTS-3 is using a unique acquisition model for the ESPAStar line that fully exercises the commercial nature of the Northrop Grumman’s product line, in order to provide the bus to another defense contractor for payload integration using standard interfaces.”
In addition to the bus delivery, AFRL took delivery of the Global Navigation Satellite System Test Architecture receiver, a reprogrammable software-defined device that can receive both GPS signals and the advanced PNT signals transmitted by NTS-3
Originally expected to launch in 2022, AFRL noted in April that the rideshare secured for NTS-3 had been pushed to fall 2023. While the lab says the delay is entirely outside its control, it will use the time to conduct more ground experimentation and risk reduction.
UPDATE: This story has been updated to further clarify that NTS-3 will not necessarily be integrated with the GPS operational system.
Nathan Strout covers space, unmanned and intelligence systems for C4ISRNET.