The Space Development Agency (SDA) is preparing for the next major procurement of satellites for the military’s low Earth orbit satellite constellation, known as the Proliferated Warfighter Space Architecture (PWSA).
Last week, satellite vendors were notified of an upcoming solicitation for an estimated 200 satellites and associated ground services under Tranche 3 of the PWSA. The procurement process is expected to begin in 2025, and SDA is calling for “improved and more focused proposals” that will enhance the capabilities of the constellation while preparing for its long-term sustainment.
An organization under the U.S. Space Force, SDA’s primary mission is to develop and deploy next-generation space systems that enhance the military’s ability to detect, track, and counter advanced threats. By leveraging commercial space technologies and rapid acquisition strategies, SDA is trying to deliver systems faster and more cost-effectively than traditional military space programs.
The PWSA, currently in its demonstration phase with just 27 satellites in orbit, is designed to serve U.S. military operations with critical capabilities such as communications, missile defense, battle management, and navigation. Over the next three years, SDA plans to launch between 300 to 400 satellites for Tranches 1 and 2.
Tranche 3 will be the first procurement of replacement satellites as some Tranche 1 spacecraft reach the end of their operational life, projected at about five years.
To prepare for the transition, SDA has already awarded $1.9 million in contracts to six companies — Arkisys, Impulse Space, Quantum Space, Sierra Space, SpaceWorks Enterprises, and Starfish Space — to study satellite removal and deorbiting options.
According to SDA Director Derek Tournear, Tranche 3 will involve approximately 140 satellites for the Transport Layer, which provides low-latency communication, and 54 satellites for the Tracking Layer, which detects and tracks advanced missile threats such as hypersonic missiles. The focus will be on upgrading existing satellites with more advanced capabilities, rather than replicating the current design.
“At the end of Tranche 3, we will begin decommissioning Tranche 1 satellites,” Tournear said, noting that the SDA’s Warfighter Council, a panel of Pentagon officials and military leaders, has approved the requirements for Tranche 3, paving the way for formal solicitations to begin in 2025.
Among the upgrades planned for Tranche 3 are phased array antennas to enhance satellite communications and enable more simultaneous users, especially those utilizing the S-band for tactical communications. Additionally, improvements to Link 16 encryption are expected to enhance the security of data transmission. The Tranche 3 Tracking Layer will also feature more sensitive infrared sensors, providing high-fidelity missile tracking necessary for real-time missile defense systems.
By 2028, when the Tranche 3 satellites are expected to be launched, SDA anticipates having at least 10 missile defense satellites in orbit. “Tranche 3 will build on that to give us global missile defense,” Tournear noted, though the exact number of satellites required to achieve this goal is still under evaluation.
The Tranche 3 transport satellites will also provide enhanced positioning, navigation, and timing (PNT) services, augmenting GPS and improving resilience in contested environments.
Despite hitting some recent milestones, the PWSA faces several near-term challenges. One significant issue is the delay in the deployment of the space-based Link 16 network due to regulatory hurdles.
While tests of Link 16 from space were successful during trials with U.S. military units in Australia and on a U.S. aircraft carrier, the system’s use within U.S. airspace remains on hold. The delay stems from concerns over interference with GPS L5 signals, a critical navigation band, which has postponed further domestic testing.
Tournear noted that while international tests continue, including planned trials with Norway, the inability to test in the U.S. could slow the overall deployment of Link 16 from space. Securing a waiver from the International Telecommunication Union (ITU) allowed the system to be tested over international waters, but domestic clearance remains a lengthy process.
Another challenge is ensuring the health of the satellite supplier base.
Tranche 1 has already faced production delays due to component shortages and supply chain bottlenecks — a problem that plagued earlier procurements. “We had huge issues in Tranche 0,” Tournear remarked, acknowledging that while suppliers are now ramping up production, there is still “some risk” to the Tranche 1 schedule, which is set to begin launches in early 2025.
Tranche 1 satellites are expected to be deployed over 10 launches on a monthly cadence, with full operational acceptance by the end of 2025.
Meanwhile, development on Tranche 2 satellites is still in the design phase, with first launches targeted for September 2026. Tournear said SDA is hopeful that lessons learned from earlier tranches will help mitigate risks and accelerate deployment timelines.