Over recent years, the space industry has witnessed exponential growth, significantly enhancing our capabilities beyond Earth. The US Department of Defense (DoD), while equipped with advanced weapon systems, is known for its lengthy procurement processes, particularly when adopting new technologies. Historically, integrating cutting-edge commercial tech into military operations has been a slow and complex endeavor.
However, the DoD is actively adapting to leverage the rapid advancements within the domestic space sector. Frank Calvelli, US Air Force acquisition lead, emphasized the necessity for change in a recent memorandum, stating that “traditional ways of doing space acquisition must be reformed.” He pointed out that relying on “a small amount of large satellites” and “large monolithic ground systems” with lengthy development cycles is no longer viable.
In response to these challenges, the Pentagon established the Space Development Agency (SDA) in 2019. Initially an independent entity, now integrated with the Space Force, the SDA’s core mission is to accelerate the deployment of emerging space technologies into the hands of warfighters.
Genesis of the SDA: Addressing Procurement Bottlenecks
The SDA emerged as a direct solution to the slow procurement cycles that hindered the adoption of innovative space capabilities within the DoD. Patrick Shanahan, then-Secretary of Defense, articulated the urgency in a 2019 memorandum, emphasizing that a “national security space architecture” providing persistent, resilient, and low-latency surveillance is crucial for maintaining a competitive advantage. He stressed that outdated methods and cultures were impeding progress and hindering the ability to match the pace of adversaries.
This imperative gave rise to the National Defense Space Architecture (NDSA), a tactical Low Earth Orbit (LEO) network. The NDSA is engineered to facilitate rapid and secure communication of critical data, including missile warnings and precise positioning, navigation, and timing (PNT) information, to ground forces.
Frank Turner, technical director of the SDA, highlighted the transformative impact of the NDSA, explaining to Payload that it will enable “data creation and pointed deployment with the least possible latency.” He emphasized the shift from mere effectiveness to true efficiency, noting that the NDSA will provide “a global efficiency that we haven’t had before” from a tactical standpoint.
Division of Responsibilities: Integrating Legacy with Innovation
While the SDA is a relatively new organization, the DoD’s involvement in space operations is extensive, dating back to the early days of rocketry and satellite technology. Over decades, various defense agencies have played roles in space asset management.
Currently, Geostationary Orbit (GEO) and Medium Earth Orbit (MEO) missile-tracking assets are primarily managed by the Missile Defense Agency (MDA) and Space Systems Command (SSC). These agencies collaborate closely with the SDA to ensure a cohesive and integrated national defense space system.
The MDA’s origins trace back to the Strategic Defense Initiative (SDI) of 1983, aimed at consolidating missile defense efforts. Officially named MDA in 2002, it operates the Ballistic Missile Defense System (BMDS), which includes a GEO constellation for missile detection and tracking.
SSC, focused on delivering “lethal and resilient” space capabilities, also possesses a long history in space services, particularly in MEO and GEO.
Turner clarified that the NDSA fills a critical gap by establishing a LEO presence, complementing the GEO and MEO capabilities of MDA and SSC. He emphasized that this integrated approach leverages each agency’s strengths to create a comprehensive missile tracking and defense architecture vital for national security.
Tranche-Based Deployment: A Silicon Valley Approach
To expedite the development and deployment of the complex NDSA system, the SDA adopted a tranche-based approach, inspired by Silicon Valley’s iterative development model. Each tranche represents a new generation of the NDSA, with scheduled launches occurring in September of even-numbered years.
This predictable schedule is designed to foster trust and collaboration with private space industry partners. Turner emphasized the importance of reliable government schedules for industry planning, stating that the SDA aims to provide “a schedule and those demands that enable the industry to go out and do the things that they need to be doing.” This “continuous acquisition process” allows for technological advancements to be incorporated in subsequent tranches if they are not ready for the current launch window.
Tranche 0, the initial deployment for the NDSA, faced delays due to chip shortages and supply chain issues, pushing the launch from September to mid-December. While a specific launch date remains unconfirmed, the SDA anticipates initial demonstrations by summer of the following year.
Image: SDA
Image: SDA showcasing the concept of tranches in the National Defense Space Architecture.
NDSA Tranches: Phased Capability Enhancement
The SDA outlines the capabilities of each tranche as follows:
- Tranche 0 (FY22): Warfighter Immersion: Demonstrates the feasibility of a proliferated architecture in terms of cost, schedule, and scalability for beyond-line-of-sight targeting and advanced missile detection and tracking. This initial tranche focuses on proving the core concepts of the NDSA.
- Tranche 1 (FY24): Initial Warfighting Capability: Establishes regional persistence for tactical data links, advanced missile detection, and beyond-line-of-sight targeting. Tranche 1 expands upon Tranche 0 to provide initial operational capabilities.
- Tranche 2 (FY26): Global Persistence for Tranche 1 Capabilities: Extends the capabilities of Tranche 1 to a global scale. This tranche incorporates lessons learned from the operation of Tranche 0 over two years, refining and enhancing the system.
- Tranche 3 (FY28): Advanced Improvements: Introduces enhanced sensitivity for missile tracking, improved targeting capabilities for BLOS, additional PNT capabilities, and advancements in blue/green laser communication and protected RF communication. Tranche 3 focuses on significant performance upgrades.
- Tranche 4 (FY30): Continual Advancement: Incorporates further advancements to the NDSA layers, addressing evolving threats to warfighters. This tranche represents ongoing adaptation and improvement of the architecture.
Seven Layers of NDSA: Functional Organization
The NDSA is structured as a proliferated LEO constellation, characterized by a large network of smaller, more affordable satellites, contrasting with traditional, expensive GEO satellites. This distributed approach enhances resilience and reduces vulnerability.
The SDA organizes the NDSA into seven functional “layers,” each contributing specific capabilities to the overall architecture. These layers include constellations, payloads, and supporting infrastructure, representing a modular and adaptable system design.
Support Layer: Foundation for Operations
The “Support” layer encompasses the essential ground infrastructure, launch systems, and overall operational framework required for the NDSA to function.
Ground systems are a central component, with plans for integration with existing global ground stations to ensure rapid data dissemination.
Launch capabilities are also part of this layer. SpaceX was awarded the contract to launch the 28 satellites for Tranche 0. Payload integration and satellite operations are managed within the Support Layer. Notably, the SDA’s first satellites were launched with SpaceX on the Transporter-2 mission in June 2021, demonstrating early progress.
Transport Layer: The Network Backbone
Image: SDA Transport Layer
Image: Illustration of the Transport Layer satellites forming a mesh network for data transmission.
The NDSA features two primary satellite constellations: the Transport and Tracking layers. The Transport Layer serves as the foundational mesh network in LEO, utilizing optical inter-satellite links for high-speed, secure data transmission. These laser-based links offer significantly faster and more secure communication compared to traditional radio frequencies, making interception considerably more difficult.
Turner described the Transport Layer as the “heartbeat of the NDSA,” responsible for routing all data across the architecture to its intended destination on the ground.
The Transport Layer employs a mesh network topology where each satellite maintains constant communication with four neighboring satellites – ahead, behind, left, and right. This interconnectedness ensures rapid and resilient data flow across the global network. This spatial distribution not only enhances speed and security but also increases the system’s survivability. The mesh network allows for data rerouting if a satellite is compromised, ensuring continuous operation. Tranche 0 includes 20 Transport Layer satellites.
Tracking Layer: Missile Detection and Observation
The Tracking Layer comprises the second satellite constellation, dedicated to remote sensing and Earth observation from LEO.
Equipped with infrared sensors, Tracking Layer satellites are designed to detect and track missile threats. These satellites are interconnected with the Transport Layer via optical links, enabling seamless data transmission across the mesh network and down to ground stations. Tranche 0 incorporates eight Tracking Layer satellites. The planned ratio of Transport to Tracking Layer satellites is expected to remain consistent as the NDSA expands with subsequent tranches.
Navigation Layer: Enhanced PNT Data
The Navigation Layer leverages the global mesh network of the Transport Layer to provide enhanced Position, Navigation, and Timing (PNT) data. While not a separate constellation, this layer adds a crucial capability to the NDSA.
Turner clarified that the Navigation Layer is not intended to replace GPS, which remains a core capability. Instead, it offers a vital backup PNT capability for scenarios where GPS is unavailable, ensuring warfighters maintain accurate time and location awareness globally.
Battle Management Layer: On-Orbit Processing
Each Transport Layer satellite hosts a Battle Management Layer payload, featuring a computer for dynamic, on-orbit processing (“edge computing”). This layer manages interactions between satellites and layers, reducing data latency and processing bottlenecks.
Turner explained that on-orbit processing minimizes the need for data to be downlinked to the ground for processing and then uplinked, significantly improving data delivery speed and efficiency.
Custody Layer: Intelligence, Surveillance, and Reconnaissance
The Custody Layer is responsible for Intelligence, Surveillance, and Reconnaissance (ISR) functions, focusing on detecting and tracking ground targets.
The SDA does not plan to deploy a dedicated Custody Layer constellation. Instead, the NDSA’s mesh network is designed to integrate data from existing ISR assets, including commercial and national intelligence satellites operated by agencies like the NRO. This eliminates redundancy and leverages existing capabilities within the space domain.
Emerging Capabilities Layer: Future Innovation
The Emerging Capabilities Layer provides flexibility for integrating new and evolving space technologies into the NDSA. Initially, this includes exploring space domain awareness capabilities.
The SDA actively collaborates with DoD offices and military personnel to identify and evaluate promising technologies. Emerging technologies under consideration include tagging and tracking systems, radio frequency identification, alternative navigation systems, and tactical communications support, ensuring the NDSA remains adaptable and cutting-edge.
Looking Ahead: NDSA Deployment and Evolution
The SDA is committed to its rapid deployment mandate, working to establish a functional NDSA for warfighters in the coming years. The architecture embodies key advancements in space technology, including optical links and on-orbit processing.
The Pentagon is closely monitoring the NDSA’s development in LEO, comparing its progress with similar initiatives in the commercial sector. The first Tranche 0 launch is anticipated imminently, potentially by mid-December or early in the new year. Following this initial launch, the SDA plans to maintain its tranche-based launch schedule, continuously deploying new generations of Transport and Tracking Layer satellites and enhancing NDSA capabilities.
