AFRL Leaps Forward in NTS-3 Spacecraft Development

Air Force Research Laboratory News Release

2021 June 24

(JUN 24) KIRTLAND AIR FORCE BASE, N.M. (AFRL) - The Air Force Research Laboratory's Navigation Technology Satellite-3 (NTS-3) satellite navigation program is closer in the development of the spacecraft for its in-space demonstration, thanks to the delivery of its bus that will carry it to space in 2023.

In 2019, the U.S. Air Force designated NTS-3 as one of three Vanguard programs, which are priority initiatives to deliver new, game-changing capabilities for national defense. The NTS-3 mission is to advance technologies to responsively mitigate interference to position, navigation and timing (PNT) capabilities, and increase system resiliency for the U.S. Space Force's Global Positioning System military, civil and commercial users.

Northrop Grumman Corporation recently delivered an ESPAStar-D spacecraft bus to L3Harris Technologies of Palm Bay, Florida in support of the NTS-3 mission scheduled to launch to geosynchronous orbit from Cape Canaveral in 2023.

The AFRL Transformational Capabilities Office at Wright-Patterson AFB and Space Vehicles Directorate, located at Kirtland AFB in Albuquerque, N.M, are in partnership with the two industry companies for the bus development and integration.

"This is the first time an ESPAStar 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 Northrop Grumman's product line, in order to provide the bus to another defense contractor for payload integration using standard interfaces."

The ESPAStar-D bus, built in Northrop Grumman's satellite manufacturing facility in Gilbert, Arizona, includes critical subsystems such as communications, power, attitude determination and control, in addition to configurable structures to mount payloads.

A June 2021 press release from Northrop Grumman explains the company built the ESPAStar-D bus "to provide affordable, rapid access to space," and that its configuration, using an Evolved Expendable Launch Vehicle (EELV) Secondary Payload Adapter (ESPA), allows multiple separate experimental payloads to be stacked together on one launch vehicle.

It should be noted that AFRL developed the ESPA ring - a technology that revolutionized the transport of space experiments, allowing for lower-cost and more frequent "rides" to space, for government and industry users.

"The transfer of the bus allows L3Harris to move forward building the NTS-3 spacecraft," said 2nd Lt. Charles Schramka, the program's deputy principal investigator. "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."

Following L3Harris's work, AFRL will test the bus with the NTS-3 ground control and user equipment segments, and will perform its own integrated testing on the overall NTS-3 system architecture.

Besides the bus delivery, there are other advances in the program.

Schramka said, "This month we took delivery of an experimental receiver known as Global Navigation Satellite System Test Architecture (GNSSTA), developed by our sister AFRL unit, the Sensors Directorate at Wright-Patterson AFB, Ohio and Mitre Corporation. GNSSTA is a reprogrammable software defined signal receiver that allows us to receive the legacy GPS and advanced signals generated by NTS-3."

AFRL will continue its integration efforts through 2022 to ensure all parts are working together for the fall of 2023 NTS-3 launch.

"With the delivery of the bus we are entering into the next phase of payload integration," Biersgreen said. "These recent breakthroughs allow the program to continue to move forward and prepare for launch of the first U.S. integrated satellite navigation experiment in over 45 years."

About AFRL

The Air Force Research Laboratory (AFRL) is the primary scientific research and development center for the Department of the Air Force. AFRL plays an integral role in leading the discovery, development, and integration of affordable warfighting technologies for our air, space, and cyberspace force. With a workforce of more than 11,500 across nine technology areas and 40 other operations across the globe, AFRL provides a diverse portfolio of science and technology ranging from fundamental to advanced research and technology development. For more information, visit: www.afresearchlab.com.

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