The first in a series of launches supporting a burgeoning satellite constellation for the Space Development Agency (SDA) is set to take flight Wednesday morning from Vandenberg Space Force Base in California.
The SDA was formed as an independent agency 2019 with the goal of safeguarding the United States against hypersonic weapons and offering a network of satellites and ground support systems that could unify the Department of Defense’s capabilities across a “resilient, threat-driven space surveillance and communications architecture,” according its establishing memorandum. It became a part of the U.S. Space Force in October 2022.
The 21 satellites, built by York Space Systems, are the first, fully operational spacecraft for the constellation known as the Proliferated Warfighter Space Architecture (PWSA). It was formerly called the National Defense Space Architecture (NDSA), but the name was changed in 2023.
The SDA said it was renamed “to more specifically reflect the agency’s mission to deliver needed space-based capabilities to the joint warfighter to support terrestrial missions through development, fielding, and operation of a proliferated low Earth orbit (pLEO) constellation of satellites.”
SpaceX is targeting launch of its Falcon 9 rocket for the Tranche 1 Transporter Layer mission from Space Launch Complex 4 East at 7:12 a.m. PDT (10:12 a.m. EDT / 1412 UTC).
Spaceflight Now will have live coverage beginning about 30 minutes prior to liftoff.
While a specific launch weather forecast wasn’t issued publicly ahead of the launch, SDA Deputy Director Gurpartap “GP” Sandhoo said on Tuesday mission teams polled ‘go’ to proceed with the final prelaunch activities ahead of the Wednesday morning launch attempt.
This mission was awarded to SpaceX as part of the National Security Space Launch (NSSL) Phase 2 contract, which is managed by the U.S. Space Force’s Space Systems Command (SSC). It was one of three missions awarded to SpaceX as part of a $309.7 million agreement.
For this first Tranche 1 mission, SpaceX will use the Falcon 9 first stage booster 1093, which will be flying for a sixth time. Its previous five flights were all in support of SpaceX’s Starlink constellation.
A little more than 8.5 minutes after liftoff, B1093 will target a propulsive landing on SpaceX’s drone ship called ‘Of Course I Still Love You,’ which will be positioned in the Pacific Ocean.
As with many national security missions a full deployment timetable was not released, but an SDA official said the 21 satellites would be deployed into a polar orbit in batches starting about an hour after launch, noting there are several minutes between each deployment sequence.
Coming soon to (war) theaters
The Tranche 1 Transport Layer (T1TL) is the first batch of operational satellites supporting the SDA’s PWSA constellation. It comes after nearly two dozen demonstration satellites were launched across three Falcon 9 flights between 2023 and 2024 as part of Tranche 0.
Breaking down some of the jargon, the SDA defines a “tranche” as the generation or iteration of satellites. Meanwhile the agency said a “layer” signifies “a particular function of the architecture that delivers or enables a warfighting capability.”
In this instance, the SDA said its Tracking Layer “will provide a mesh network comprised of communication satellites that connect to one another and to other space vehicles and ground stations via optical intersatellite links (OISLs).”
That “mesh” refers to the optical lasers used to connect the satellites in orbit between one another as well as to ground stations around the world.
“The Tracking Layer and Custody Layer provide sensing functions for advanced missile threats and time-critical land and maritime targets, and connect to the Transport Layer to provide threat indications and targeting data to our warfighters in real time,” the SDA stated on its website.
During a prelaunch briefing on Tuesday, Sandhoo described the Transport Layer as a type of “relay” that helps extend sensitive, tactical communications beyond a line of sight. Right now, that’s a limitation of Link 16 radios, which are a secure communications system used by NATO and its partners.
“Now (following the incorporation of this technology), you’re able to talk not only to within a couple of miles with your Link 16 radios,” Sandhoo said. “We can use space to go, let’s say, go from Hawaii out to Guam using those tactile radios, using a space layer… as a relay.”
York Space Systems announced the completion of its first 21 T1TL satellites back in April 2025. They were initially awarded a $382 million contract to develop 42 of these satellites, but due to reworking some aspects of the satellites and delays to the launch schedule, that price tag went up.
“Each of the [space vehicles] for Tranche 1 Transport is going to be around $14 to $15 million a unit,” Sandhoo said. “I think that number is going to be pretty consistent. These are fixed-price contracts, but we’ve had to fix things and adapt as needed to make sure we deliver it.”
There are 10 launches planned for Tranche 1, which include six within the Transport Layer and four within the Tracking Layer. Sandhoo said SDA is aiming for a launch cadence of roughly once per month with the next flight expected during the second week of October, this time featuring T1TL satellites from Lockheed Martin.
source: spaceflightnow.com