On Orbit captures the current and past SDA efforts that have been launched into low Earth orbit. SDA continues to push the boundaries of next-generation space capabilities and what we put on orbit is the leading edge. As an agency, we accept a higher level of risk, employ novel business models, and move to develop and field capabilities more quickly than many other "traditional" government agencies and nowhere is that more apparent than what we have on orbit.
Tranche 1:
Initial Warfighting Capability Tranche
The Tranche 1 (T1) constellation will serve as the initial warfighting capability for the Proliferated Warfighter Space Architecture (PWSA) and provide regional persistence for Link-16 and Ka-band military tactical communications, advanced missile tracking and missile warning, and beyond-line-of-sight targeting.
Key Capabilities & Specifications
- Constellation Size: 154 operational Space Vehicles (SVs) across 10 orbital planes
- 126 Transport Layer SVs
- 28 Tracking Layer SVs
- Connectivity: Each T1 Space Vehicle (SV) is configured with optical communication terminals (OCTs) for satellite-to-satellite and satellite-to-ground optical communications and Ka-band radio frequency (RF) receive/transmit capability. Additionally:
- Transport Layer SVs are configured with Link 16 tactical data link (TDL) transmit/receive capability.
- Tracking Layer SVs are configured with an infrared sensing payload for Missile Warning/Missile Tracking.
- Cost: The average cost of each Transport Layer Tranche 1 SV space vehicle is approximately $14 million.
To learn more, check out the Tranche 1 Fact Sheet
Tranche 1 Launch Campaign
The T1 SVs are being deployed across 10 orbital planes via 10 dedicated launches procured via the National Security Space Launch (NSSL) program.
T1 Launch Status
Tranche 1 Demonstration and Experimentation System (T1DES) Proto
The Tranche 1 Demonstration and Experimentation System (T1DES) is a risk reduction effort that will demonstrate secure connectivity to warfighter platforms to support integration of capabilities like targeting, and warning and tracking of advanced missile threats.
- SDA signed an agreement with York Space Systems in September 2022 for the development, manufacturing, testing, launch integration, mission-enabling ground systems, and deployment of T1DES.
- A single pathfinder satellite, referred to as T1DES Proto (for “prototype”) or by York’s program name "Dragoon," launched on SpaceX’s Transporter-14 from Vandenberg Space Force Base, California, on June 23, 2025.
- This launch represented accelerated delivery of the T1DES space vehicle, placing it on orbit four months ahead of the original baseline schedule.
- Since launch, T1DES Proto has successfully executed a campaign of tactical satellite communications (TACTSATCOM) demonstrations, completing the T1DES mission while also serving as a bus and payload pathfinder for future Proliferated Warfighter Space Architecture (PWSA) Tranche 1 and Tranche 2 missions.
Tranche 0: Warfighter Immersion Tranche
Tranche 0, the Warfighter Immersion Tranche, demonstrates the feasibility of a proliferated architecture in cost, schedule, and scalability toward necessary performance for beyond line of sight targeting and advanced missile warning and tracking.
Constellation Size: 20 SVs, which form the mesh satellite communications network.
Major Milestones
- Demonstrated the low latency data transport and missile warning/tracking capabilities of the PWSA and enables the warfighter to integrate PWSA capabilities into their planning for future exercises and operations (warfighter immersion).
Space Vehicles
The majority of the on-orbit Tranche 0 constellation operates at an altitude of approximately 1,000 km at an 80° orbital inclination across three primary planes:
- Transport Layer (These SVs are deployed in two configuration)
- Group A (SVA): 13 mesh node SVs equipped with two optical communications terminals (OCTs) each & radio frequency (RF) receive/transmit capability.
- Group B (SVB): 7 SVs, with SVA configuration, plus tactical data link (TDL) receive/transmit capability.
- 19 SVs on-orbit, 1 T0 Transport Layer SV remains on the ground to serve as a testbed for software and compatibility with future Tranches.
- Cost is approximately $15 million per Transport SV.
- Tracking Layer
- 8 SVs equipped with the wide field of view (WFOV) sensor payload and two OCTs each.
Launch
- 2 commercially acquired SpaceX F9R (reusable) rocket launched from Vandenberg Space Force Base, Space Launch Complex (SLC) 4 East, for the first two launches in April and September 2023.
- The final Tranche 0 launch of four Tracking Layer SVs is a joint National Security Space Launch with the Missile Defense Agency's Hypersonic and Ballistic Tracking Space Sensor satellites out of Cape Canaveral Space Force Station, Florida in February 2023.
To learn more, check out the Tranche 0 Fact Sheet.
LINCS Overview
The Laser Interconnect and Networking Communication System (LINCS) program is an experiment in partnership with General Atomics. The two LINCS space vehicles will test space-to-space, space-to-air, and space-to-ground optical communication terminals. Initial goals for LINCS include:
- Evaluation of pointing, acquisition, and tracking algorithms
- Characterization of transfer rates and bit-error rates
- Evaluation of optical link performance both space-to-space, space-to-ground, and space-to-air.
- Implementation of a pod-mounted OCT capability for Low Probability of Intercept/Low Probability of Detection (LPI/LPD) evaluation.
Successful testing of LINCS is expected to bring first of its kind capabilities for LPI/LPD and continued evolution of technology in the area of OCT.
PIRPL Overview
Prototype Infrared Payload (PIRPL) is a medium field-of-view, multi-spectral infrared imager developed in partnership with the Missile Defense Agency and Northrop Grumman. The experiment will launch on Cygnus resupply mission NG-16 to the International Space Station (ISS), where it will undergo commissioning and initial data collection while berthed with the ISS. After the berthed mission completes, a free-flyer phase is planned in which PIRPL will perform additional data collections from an orbit above the ISS. PIRPL's primary objective is to collect representative infrared (IR) background images of the Earth and its atmosphere in multiple wavelengths. PIRPL data will enable improvement of existing IR scene models and development of advanced image processing capabilities. PIRPL data will span several infrared wavebands in the shortwave and midwave IR range that can also support weather and environmental monitoring missions in the future. Successful imagery from PIRPL may inform future SDA tranche evolution.
Mandrake II Overview
Mandrake II is an optical communication terminal (OCT) experiment in partnership with the Air Force Research Laboratory and the Defense Advanced Research Projects Agency. The two space vehicles are a primary contract with SEAKR and specifically with OCTs from SA Photonics. The experiment will test optical links at increasing ranges with an expected maximum distance of 2400 kilometers, based on orbital limitations. Initial goals for Mandrake II include:
- Evaluation of pointing, acquisition, and tracking algorithms
- Characterization of transfer rates and bit-error rates
- Evaluation of optical link performance both space-to-space and space-to-ground.
Successful testing of Mandrake II is expected to inform design modification and updates for future OCTs and provide risk mitigation for future tranche evolution.
POET Overview
Prototype On-Orbit Experimental Testbed (POET) is a Space Development Agency (SDA) Scientific Systems Company flying on a Loft Orbital YAM-3 spacecraft. POET will provide an on-orbit Custody Layer data fusion application that will reside within an overarching Battle Management Command, Control, and Communications (BMC3) software system. Initial objectives:
- Demonstration of an Automatic Target Recognition (ATR) algorithm with an Electro-optical sensor on board the Loft Orbital spacecraft bus
- Accommodation of 3rd party developed algorithms for fusion of data from multiple remote sensing sources
- Early experience with the spacecraft's CFC-400 processor's finite size, weight, and power
- Early orbital testing for future Custody Layer mission applications
- Battle Management Command, Control, and Communication (BMC3) insights and test opportunities
