U.S. Space Development Agency Prepares For Critical Tech Demonstrations

The Space Development Agency is on the cusp of proving out a massive experiment in Pentagon acquisition and military space operations. First, it must relay data among its on-orbit systems, from space to an airborne system and to ground receivers.

The five-year-old agency’s signature Proliferated Warfighter Space Architecture (PWSA) will include hundreds of satellites stationed in low Earth orbit (LEO), and a new tranche of satellites is planned come online every two years. The constellation includes an evolving set of low-latency communication transport satellites for 24/7 data transmission and a tracking layer of satellites to detect and monitor ballistic missile threats in real time. Once fully fielded, the PWSA also is intended to enable enhanced battle management, navigation, ground support and deterrence from space.

• The agency demonstrated Link 16 from space to air and ground
• More tests are planned before year-end to study on-orbit optical and laser communications to airborne systems

This massive, rotating constellation hinges on the ability of the Space Development Agency (SDA) to demonstrate intersatellite connectivity using onboard optical communication terminals (OCT) as well as laser connectivity among space systems and airborne and ground assets.

The agency first tested space-to-space data relay between two prototype satellites in 2021 under a partnership with DARPA. But since launching its initial batch of 27 Tranche 0 satellites between late 2023 and early 2024, the SDA has prioritized ramping up on-orbit demonstrations for both the transport and tracking layer satellites.

York Space Systems and Lockheed Martin each built 10 satellites for the Tranche 0 transport layer while SpaceX and L3Harris developed four satellites, each equipped with wide-field-of-view sensors for the tracking layer. The SDA plans to launch the next 154 tracking and transport layer satellites under Tranche 1 by year-end, representing the first operational batch of spacecraft for the PWSA.

The agency is using the Tranche 0 satellites to demonstrate the most critical technologies that the PWSA needs to prove out in order to be viable: Link 16 data transmission from space to ground, airborne and space systems; space-to-space optical communications; and laser communications among space and airborne systems.

The SDA prioritized Link 16 from space early on because it would provide the most immediate capability—and lowest adoption burden—to the warfighter, says the agency’s director, Derek Tournear. The Link 16 tactical data link communication system is used by the U.S. along with its NATO and coalition partner forces to transmit and exchange real-time situational awareness data among network participants.

The first attempt to demonstrate Link 16 from space occurred in November 2023, when the SDA transmitted data from three Tranche 0 satellites built by York Space Systems to ground-based radios located at an Australian test site. The test was conducted first over Australian sovereign territory, then over international waters.

The connection made during that initial test was not very reliable, says Melanie Preisser, York Space Systems executive vice president and general manager.

“We were able to enter the Link 16 network, but we weren’t able to maintain that linkage throughout the entire satellite pass,” Preisser tells Aviation Week. The company worked with the SDA in the spring to perform about 50 additional test events during which the York-built satellites successfully connected multiple times to Link 16 ground receivers, she says.

Those tests culminated in a Link 16 data transmission in July among the Tranche 0 satellites in LEO and a U.S. Navy aircraft carrier in international waters as well as an aircraft stationed aboard the ship. Over a two-day period, the SDA demonstrated “consistent” linking from LEO to ground, mobile and maritime Link 16 radios and antennas, Damon Feltman, the agency’s transport cell chief, said on Aug. 8 at the Space and Missile Defense Symposium in Huntsville, Alabama.

Demonstrating that the transport satellites could connect reliably to the Link 16 network was “the biggest concern” so far, Tournear says.

“We are now focused fully on getting the transport satellites to do the optical communication,” he says, noting that the goal is to link two satellites from separate vendors by the end of September. “Getting York to talk to York [or] getting SpaceX to talk to SpaceX is one thing. But we want to demonstrate that we can have those two talk to each other,” he says.

October’s test campaigns will focus on demonstrating space-to-air laser communications with several pathways using separate air vendors, Tournear says. The agency has agreements with TESAT Government, Calspan and General Atomics to conduct a series of OCT-related tests in the coming months.

One of those tests, dubbed Stallion, will involve a space-to-airborne demonstration for which General Atomics is building an airborne OCT to be flown on a De Havilland Canada DHC-6 Twin Otter aircraft leased by the SDA. The OCT will need to connect with a space-based terminal already in orbit, says Gregg Burgess, General Atomics vice president for space systems. That test could occur by year-end, pending the success of earlier optical communications demos.

“They need to get the space-to-space crosslinks demonstrated before moving to the space-to-air” mission, Burgess says. General Atomics is the payload provider for Lockheed Martin’s satellites in development for the SDA’s Tranche 2 tracking layer.

General Atomics also is participating in an experiment called Manhattan, which involves two OCT General Atomics built to the SDA’s standard that will fly on two company-developed spacecraft.

The GA-75 spacecraft fitted with OCT is planned to demonstrate space-to-space crosslink data relay in degraded environments, meeting the agency’s specifications for data rate and range. It also is intended to be capable of performing space-to-ground and space-to-air communications, Burgess says. The company is funding the design and hardware build while the SDA is paying for some of the spacecraft operations as well as the launch of the two satellites. General Atomics plans to integrate the complete systems in its Centennial, Colorado, facilities late this year and be “ready to launch” by the second quarter of 2025, although a ride has not yet been purchased, Burgess says.

On Sept. 3, the SDA hit a new milestone when it connected two SpaceX Tranche 0 tracking-layer birds using TESAT-built optical communications terminals, Tournear said on Sept. 4 during the Defense News Conference in Washington. Acquiring the link between the two spacecraft took about 10-100 sec.; the link was maintained for several hours.

“From my perspective, we have demonstrated all of the big rocks and burned down all of the risk for Tranche 1 in Tranche 0, based on that success last night,” he said.