Support Equipment

Transport and Tracking Layer

Also known as
  • PWSA Transport and Tracking Layer
  • SDA Transport and Tracking Layer
  • Proliferated Warfighter Space Architecture Transport Layer
  • Proliferated Warfighter Space Architecture Tracking Layer
  • PWSA Transport Layer
  • PWSA Tracking Layer
  • PWSA

Transport and Tracking Layer covers the Space Development Agency's proliferated low-Earth-orbit satellite architecture for resilient military data transport, tactical links, missile warning, and missile tracking. Publicly documented activity centers on launches, demonstrations, contractor awards, and planned warfighter integration rather than confirmed conflict employment.

Transport and Tracking Layer, Proliferated LEO communications and missile-tracking satellite architecture, Support Equipment
Image source: SDA completes first Tranche 1 satellite launch
Profile / Specs

Specifications

Orbit
Low Earth orbit, with SDA fact sheets listing 1,000 km orbital altitude for T0/T1 Transport and Tracking Layer summaries
Transport Layer mission
Low-latency data transport, sensor-to-shooter connectivity, tactical satellite communications, and persistent encrypted connectivity
Tracking Layer mission
Infrared missile warning, missile tracking, identification of advanced missile threats, and fire-control-quality missile-defense sensing in later tranches
Tranche 1 constellation
154 operational space vehicles planned: 126 Transport Layer satellites and 28 Tracking Layer satellites
Tranche 2 constellation
Approximately 270 operational Transport and Tracking Layer satellites when completely fielded
Tranche 3 Tracking Layer
72 Tracking Layer satellites across eight orbital planes, each with infrared, optical-communications, Ka-band, and backup S-band TT&C payloads
Layer Architecture

The architecture combines two linked satellite functions rather than a single vehicle model: Transport Layer satellites move mission data through optical, RF, and tactical data links, while Tracking Layer satellites sense missile launches and pass mission data into the same mesh and ground system.

LayerPrimary roleDocumented payloads or interfaces
Transport LayerLow-latency communications backbone for Joint All-Domain Command and Control and tactical satellite communications.Optical communication terminals, Link 16, Ka-band RF payloads, BMC3 module, NEBULA-compatible networking.
Tracking LayerMissile warning, missile tracking, and later missile-defense fire-control sensing from proliferated LEO satellites.Infrared sensing payloads, optical communication terminals, Ka-band links, S-band backup telemetry, and interfaces with the Transport Layer mesh.
Ground and user linksOperations, tasking, and tactical data delivery to warfighter platforms and external mission partners.Space Operations Centers, global ground entry points, optical ground terminals, tactical data links, and mission-partner nodes.
Variants

SDA organizes the architecture into functional layers and two-year acquisition tranches. Transport Layer rows describe data-relay and tactical-communications satellites; Tracking Layer rows describe infrared missile-warning, missile-tracking, and missile-defense sensing satellites.

VariantConfigurationDesignation notes
Transport LayerData transport and tactical communications layer

SDA describes the Transport Layer as the PWSA mesh backbone for low-latency data transport, sensor-to-shooter connectivity, and tactical satellite communications direct to platforms.

Sources: SDA Transport Layer fact sheet

Tracking LayerMissile-warning and missile-tracking layer

SDA describes the Tracking Layer as a proliferated LEO constellation of infrared-sensing satellites for detecting and tracking conventional and advanced missile threats, including hypersonic systems.

Sources: SDA Tracking Layer fact sheet

Tranche 1 Transport LayerInitial operational data-transport tranche

The 2022 Tranche 1 Transport Layer awards covered 126 space vehicles in six near-polar planes, with York Space Systems, Lockheed Martin Space, and Northrop Grumman each building 42 satellites.

Sources: SDA awards Tranche 1 Transport Layer prototype agreements

Tranche 2 Transport Layer AlphaGlobal communications variant

SDA awarded 100 Alpha-variant Tranche 2 Transport Layer satellites to York Space Systems and Northrop Grumman for global communications and persistent encrypted connectivity.

Sources: SDA awards Tranche 2 Transport Layer Alpha satellites

Tranche 2 Transport Layer BetaAdvanced tactical communications variant

SDA awarded the Beta variant first to Northrop Grumman and Lockheed Martin and then added Rocket Lab, bringing the Beta constellation to 90 space vehicles.

Sources: SDA awards Tranche 2 Transport Layer Beta satellites, SDA awards additional Tranche 2 Transport Layer Beta satellites

Tranche 2 Transport Layer GammaTACSATCOM demonstration variant

The Gamma variant adds 20 Tranche 2 Transport Layer space vehicles from York Space Systems and Tyvak to expand advanced tactical satellite communications demonstrations.

Sources: SDA awards Tranche 2 Transport Layer Gamma satellites

Tranche 2 Tracking LayerGlobal missile-tracking and preliminary fire-control tranche

SDA awarded 54 Tranche 2 Tracking Layer satellites to L3Harris, Lockheed Martin, and Sierra Space, with each vendor providing wide-field missile-warning/missile-tracking vehicles and two missile-defense infrared-sensor vehicles.

Sources: Space Development Agency Makes Awards to Build 54 Tranche 2 Tracking Layer Satellites

Tranche 3 Tracking LayerExpanded missile-warning, tracking, and defense tranche

SDA's Tranche 3 Tracking Layer awards cover 72 satellites from Lockheed Martin, Rocket Lab, Northrop Grumman, and L3Harris, with fiscal-year 2029 launches planned.

Sources: SDA awards Tranche 3 Tracking Layer satellites

Timeline

Transport and Tracking Layer Key Events

  1. SDA awards the Tranche 1 Transport Layer

    The Space Development Agency awarded prototype agreements for a 126-space-vehicle Tranche 1 Transport Layer mesh network built by York Space Systems, Lockheed Martin Space, and Northrop Grumman.

    Sources: SDA awards Tranche 1 Transport Layer prototype agreements

  2. Tranche 2 Transport Layer Beta awards begin

    SDA selected Northrop Grumman and Lockheed Martin for 72 Beta-variant Tranche 2 Transport Layer satellites that add advanced tactical communications to the PWSA.

    Sources: SDA awards Tranche 2 Transport Layer Beta satellites

  3. SDA awards Tranche 2 Transport Layer Alpha

    SDA awarded 100 Alpha-variant Tranche 2 Transport Layer satellites to York Space Systems and Northrop Grumman, expanding the Transport Layer's global communications role.

    Sources: SDA awards Tranche 2 Transport Layer Alpha satellites

  4. SDA awards the Tranche 2 Tracking Layer

    SDA awarded 54 Tranche 2 Tracking Layer satellites to L3Harris, Lockheed Martin, and Sierra Space for missile warning, missile tracking, and preliminary missile-defense fire-control sensing.

    Sources: Space Development Agency Makes Awards to Build 54 Tranche 2 Tracking Layer Satellites

  5. First Tranche 1 Transport Layer launch reaches orbit

    A Falcon 9 launched 21 York Space Systems-built Tranche 1 Transport Layer satellites from Vandenberg Space Force Base for SDA's first operational PWSA Tranche 1 launch.

    Sources: SDA completes first Tranche 1 satellite launch

  6. Lockheed Martin-built Transport Layer satellites launch

    SDA reported that the second Tranche 1 orbital-plane launch delivered another 21 Transport Layer satellites provided by Lockheed Martin.

    Sources: ON ORBIT - Space Development Agency

  7. SDA awards Tranche 3 Tracking Layer satellites

    SDA awarded four Tranche 3 Tracking Layer agreements for 72 satellites, split among Lockheed Martin, Rocket Lab, Northrop Grumman, and L3Harris.

    Sources: SDA awards Tranche 3 Tracking Layer satellites

Media

Transport and Tracking Layer Images

Transport and Tracking Layer, Proliferated LEO communications and missile-tracking satellite architecture, Support Equipment - view 1
Source: SDA completes first Tranche 1 satellite launch
Transport and Tracking Layer, Proliferated LEO communications and missile-tracking satellite architecture, Support Equipment - view 2
Source: SDA completes first Tranche 1 satellite launch
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Sources

SDA Transport Layer fact sheetPublisher: Space Development Agency | Note: Supports the Transport Layer mission, LEO orbit, NEBULA mesh-network context, optical communication terminals, Link 16, Ka-band, BMC3, and tranche terminology. | Accessed: 2026-07-01SDA Tracking Layer fact sheetPublisher: Space Development Agency | Note: Supports the Tracking Layer's infrared missile-warning and missile-tracking role, its integration with the Transport Layer, and the 1,000 km T0/T1 tracking summary. | Accessed: 2026-07-01SDA awards Tranche 1 Transport Layer prototype agreementsPublisher: Space Development Agency | Note: Supports the Tranche 1 Transport Layer's 126-space-vehicle plan, contractor split among York Space Systems, Lockheed Martin Space, and Northrop Grumman, optical links, Link 16, Ka-band, and BMC3 payloads. | Accessed: 2026-07-01SDA awards Tranche 2 Transport Layer Beta satellitesPublisher: Space Development Agency | Note: Supports the initial Tranche 2 Transport Layer Beta awards to Northrop Grumman and Lockheed Martin, the 72-space-vehicle plan, and the advanced tactical communications role. | Accessed: 2026-07-01SDA awards Tranche 2 Transport Layer Alpha satellitesPublisher: Space Development Agency | Note: Supports the 100-satellite Alpha-variant award, the York Space Systems and Northrop Grumman split, and the Tranche 2 Transport Layer global communications role. | Accessed: 2026-07-01SDA awards additional Tranche 2 Transport Layer Beta satellitesPublisher: Space Development Agency | Note: Supports the Rocket Lab addition to the Tranche 2 Transport Layer Beta program, the increase to 90 Beta space vehicles, and the approximate 270-satellite Tranche 2 architecture. | Accessed: 2026-07-01SDA awards Tranche 2 Transport Layer Gamma satellitesPublisher: Space Development Agency | Note: Supports the 20-satellite Gamma-variant award to York Space Systems and Tyvak and the advanced TACSATCOM demonstration role. | Accessed: 2026-07-01Space Development Agency Makes Awards to Build 54 Tranche 2 Tracking Layer SatellitesPublisher: Space Development Agency | Note: Supports the Tranche 2 Tracking Layer's 54-satellite award, L3Harris, Lockheed Martin, and Sierra Space contractor roles, fire-control-quality infrared-sensor context, and approximately 270-satellite Transport and Tracking architecture. | Accessed: 2026-07-01SDA completes first Tranche 1 satellite launchPublisher: Space Development Agency | Note: Supports the Sept. 10, 2025 first Tranche 1 launch, the 21 York-built Transport Layer satellites, planned 154-space-vehicle Tranche 1 constellation, Space Operations Centers, and SpaceX photo credit. | Accessed: 2026-07-01ON ORBIT - Space Development AgencyPublisher: Space Development Agency | Note: Supports the on-orbit status of Tranche 1 launches, the second 21-satellite Lockheed Martin Transport Layer launch, the 154-space-vehicle Tranche 1 composition, the approximate T1 Transport Layer unit cost, and SDA image provenance. | Accessed: 2026-07-01Proliferating Space-Based Missile Tracking To Defeat Evolving ThreatsPublisher: Lockheed Martin | Note: Supports Lockheed Martin's Tranche 2 Tracking Layer role, the Terran Orbital bus and General Atomics payload context, SmartSat software, and the header image provenance. | Accessed: 2026-07-01SDA awards Tranche 3 Tracking Layer satellitesPublisher: Space Development Agency | Note: Supports the Tranche 3 Tracking Layer 72-satellite award, the Lockheed Martin, Rocket Lab, Northrop Grumman, and L3Harris vendor split, payload fit, eight-plane structure, fiscal-year 2029 launch plan, and Transport Layer integration. | Accessed: 2026-07-01