NATIONAL HARBOR, Md.—The Space Development Agency (SDA) continues to advance the communications capabilities of its first batch of satellites on orbit as part of the Proliferated Warfighter Space Architecture (PWSA), demonstrating sustained linkages between two satellites for more than a day at a time, the agency’s top official said on Monday.
Two weeks ago, the two SpaceX-built tracking layer satellites in Tranche 0 were demonstrating the ability to maintain a link between their respective optical laser communications terminals for two to three hours at a time before losing the connection and now that linkage is exceeding 24 hours before dropping, Derek Tournear told reporters at the annual Air Force Association Air, Space & Cyber Conference.
“They drop link maybe once every other day and then it takes them under 100 seconds to regain that link again, so that’s essentially where we need it to be for an operational system,” he said during a roundtable.
York Space Systems, which has eight transport layer satellites in orbit as part of Tranche 0, demonstrated optical communications networking on its satellites, Tournear said. Next up is to have York’s and SpaceX’s satellites communicate with each other, he said.
Like SpaceX, York’s optical terminals are supplied by Tesat on the Tranche 0 spacecraft. York said that it is the only Tranche 0 satellite “provider to make a space-to-ground Link 16 link and the only current provider to successfully demonstrate a laser link.”
Tournear said the risk is low that optical terminals between the two vendors’ spacecraft will not communicate given that the links must meet the interfaces and standards set by SDA, and because the companies have had to demonstrate that their respective links work at the optical and networking testbed hosted by the Naval Research Laboratory.
The Tranche 0 satellites are a prototype and experimentation effort to prove out the key requirements of the PWSA, which is to prove that Link 16 communications can be done from space down to air-, land-, and sea-based assets, that tracking of advanced missile threats can be done, and that an optical mesh network can be formed and maintained in space. All three questions have been answered affirmatively, Tournear said, describing Tranche 0 as an “unmitigated success.”
The goal of the PWSA is to create a proliferated constellation of satellites in low Earth orbit that can be updated every two years via new launches of spacecraft that help give the Defense Department joint all-domain command and control to enable direct tactical satellite communications to platforms and sensor-to-shooter connectivity.
So far, the Link 16 demonstrations have worked every time, Tournear said.
“Essentially, 100 percent of our links work every time we go in,” he said. “When someone’s prepared to listen to us, we transmit, receive, and that works.”
The satellites equipped with Link 16 have been maintaining contact for about 10 minutes, and this has been “working exceptionally well,” Tournear said. When the Tranche 1 satellites are on orbit, there will be 126 equipped with Link 16 and the connectivity will be longer per satellite, he said.
“So, essentially anytime you’re on the globe, you’ll be able to look up and have at least one, if not two to four Link 16 satellites overhead at any given time so you’ll have that assured connectivity with that network,” he said.
The missile tracking tests so far have used the SpaceX satellites, which have detected launches of larger launch vehicles, short-range ballistic missiles, and the re-entry in June of the upper stage of the Starship launch vehicle, Tournear said.
Tournear said that when the PWSA is operational, the tracking satellites will quickly sense the types of advanced, short-range missiles being used in the Russo-Ukrainian War and the multiple salvos launched at Israel in April, and transmit the data to warfighters.
“So, we would see that being able to get those data into theater much quicker than is traditionally done,” he said.
Missile tracking to date has been done with the SpaceX craft that include sensors provided by Leidos [LDOS]. Tracking satellites provided by L3Harris Technologies [LHX] that also include the company’s sensors are being tested and calibrated and are expected to begin tracking missile launches in early October, Tournear said.
Launches of the next set of PWSA satellites will begin in early 2025, Tournear said. Earlier this month, he said the agency was shooting for late 2024 or early 2025 to begin launching Tranche 1 but that timeframe is now early next year due mostly to continued challenges with tier one and two suppliers.
Schedule slips in SDA parlance are “weeks,” Tournear said, suggesting the first Tranche 1 launches will be in January, and February at the latest.