Small Satellites, Big Constellations

The Space Development Agency seeks to revolutionize U.S. military
space capabilities with the National Defense Space Architecture. This
consists of large constellations of small satellites providing various
capabilities. As shown in an SDA graphic above, these include a global,
persistent, low-latency data and communications transport layer; a
tracking layer monitoring and providing warning for advanced missile
threats; a custody layer providing around-the-clock, all-weather tracking
of mobile time-sensitive targets; a low-latency battle management layer
to support the rapid targeting of threats; position, navigation and timing
for GPS-denied environments; and a layer for emerging capabilities.

The military use of space traces many of its fundamental practices to when the U.S. first began exploiting the domain at the start of the Space Race in the 1950s. Over this period, numerous applications emerged, including positioning, navigation and timing (PNT); communications; and intelligence-gathering.

These capabilities generally relied on a limited number of large, expensive and slow-to-develop satellites. In the U.S., space capabilities were divided among the military services, creating a siloed, occasionally duplicative system. Although this architecture worked during the Cold War, a new generation of space technology and a rapid shift in the operating environment has created the need for a new paradigm.

To chart a new path, the Pentagon established the Space Development Agency (SDA) in 2019 to develop unified, next-generation space capabilities. The agency responded with the National Defense Space Architecture (NDSA). Rooted in an emerging concept of a low Earth orbit (LEO) constellation architecture, the NDSA represents a potentially revolutionary step forward in military space capabilities. The question remains whether the SDA and the military can bring the project to fruition.

Wobbly Beginnings
The establishment of the SDA in March 2019 did not go smoothly. Air Force Secretary Heather Wilson opposed its creation, arguing that it produced an unnecessary layer of bureaucracy in the space acquisition process. Officials also struggled to articulate a clear mission for the agency.

Once in place, the Space Development Agency was formally given its mission: to define, develop and field novel and innovative solutions to outpace advanced threats; program policy development; and the execution of next-generation military space capabilities outside the military intelligence budget. Unlike previous organizations focused on space capabilities, the SDA was placed under the office of the undersecretary of defense for research and engineering rather than within one of the services.

A Constellation of Capabilities
In July 2019, then-acting SDA Director Derek Tournear (he was named permanent director later in the year), unveiled initial plans to field several systems featuring the following capabilities:

•  Defensive cyber, anti-spoofing and anti-jamming;
• A variety of satellites at different orbits to provide coverage redundancy;
• Cross-networked satellites and ground systems that can continue to operate if part of the network or satellites are taken out;
• Improved launch and payload capabilities;
• Alternatives to GPS;
• Overlapping, persistent coverage focused on regional threat areas and then expanded to worldwide monitoring;
• Sensor satellites to detect activity around Earth and in deep space, including satellites in lunar orbit; and
• Optimizing space-to-ground data links through improved bandwidth management, hardware and software algorithms.

The new vision involves hundreds of small satellites hosting one or more payloads operating in a mesh network, which use intrasatellite data links to connect the entire constellation. Such an architecture would provide a new measure of resiliency through numbers, since the loss of one or two vehicles would not cripple the capability. This new architecture would also be driven by a new, accelerated two-year development cycle.

The concept subsequently evolved into the National Defense Space Architecture (NDSA). The NDSA is rooted in the commercial idea of constellations consisting of several layers, each with several hundred small satellites, operating in low Earth orbit. New capabilities would be implemented in two-year tranches, adding new technology as it emerged, a significant improvement over the 10- to 15-year development cycle of previous satellite programs.

Plans call for the NDSA to have six space-based layers and a ground-based command-and-control layer:

• The Transport Layer would provide communications between the different layers and connect them to troops on the ground;
• The Tracking Layer would provide indication, warning, tracking and targeting of missile launches, including hypersonic and ballistic missiles;
• The Battle Management Layer would provide architecture tasking, mission command-and-control and data dissemination capabilities to support time-sensitive operations;
• The Custody Layer would provide round-the-clock, all-weather tracking of mobile surface targets to support missile targeting;
• The Navigation Layer would provide alternate PNT capabilities to support operations in GPS-denied environments;
• The Emerging Capabilities layer would pioneer new concepts, with an initial focus on developing a Deterrence Layer to monitor activities in deep space between geosynchronous and lunar orbits to deter adversary activity through detection and attribution; and
• The Support Layer would be a common, resilient ground-support infrastructure system enabling the military to transmit, receive, process, exploit and disseminate data from the NDSA.

The final form proposed by the SDA includes hundreds of satellites spread across multiple planes. Once the constellation reaches its full strength of several hundred to more than 1,000 satellites, the agency would shift to “updating” the constellation, launching new satellites with enhanced capabilities to replace older spacecraft that have reached the end of their service lives.

The NDSA is also expected to play an important part in the Pentagon’s Joint All Domain Command and Control (JADC2) vision to link sensors and shooters across the military services. Systems like the Tracking Layer would be a key enabler by providing a service-agnostic system through which data and communications are routed.

1st Satellites Take Shape
Since rolling out the NDSA in 2019, the SDA has focused on developing prototypes for the Transport Layer and Tracking Layer. The agency is pursuing an initial batch of satellites built by two companies to demonstrate the capability for both layers.

SDA Director Tournear announced in April 2020 that Tranche 0 of the Transport Layer would involve 20 satellites to be launched by the fourth quarter of fiscal 2022. These would be expected to meet six goals: Low-latency data transport over optical data links on a mesh network; taking data from a space sensor and moving it to forces on the ground; demonstrating limited battle management, command, control and communication (BMC3) functionality; transferring integrated broadcast system data across the network; storing, relaying and transmitting Link 16 data; and maintaining a common time reference to operate independent of GPS.

The initial solicitation for the satellites was released on May 1, 2020, and contracts were let four months later. Lockheed Martin and York Space Systems were selected to build satellites to be launched by September 2022. Seven satellites from each company would be equipped with four optical crosslinks to talk with satellites in their orbital plane as well as other planes, while the other two would feature two cross links and two downlinks to connect with the Link 16 network. Lockheed and York would both have to demonstrate that their hardware, including the optical cross links, was compatible with the other’s.

The Constellation Picks Up Speed
The NDSA program barreled ahead, with contracts awarded on Oct. 5, 2021, to L3Harris and SpaceX to build the Tracking Layer Tranche 0 spacecraft. Each company would build four satellites capable of detecting and tracking ballistic and hypersonic missiles for delivery by September 2022. These contracts were delayed for several months by protests, but work is now moving forward.

Each satellite would feature a wide-field-of-view overhead persistent infrared sensor as well as optical crosslinks to pass data to the Transport Layer. While L3Harris would design and build the satellite and sensor in house, SpaceX based its bid on its commercial Starlink bus and would acquire the sensor from a third party.

Spreading the satellite orders between several contractors helps the SDA build resilience in the program and forces contractors to employ an open architecture. The agency has also managed to keep the average cost per satellite in Tranche 0 to about $14 million. Brian Weeden, a space expert at the Secure World Foundation, told Military Periscope that part of the way the SDA plans to achieve low costs and drive down risk is by taking advantage of the active, high-volume production lines of commercial providers.

Meanwhile, the SDA also awarded a $17 million contract to Perspecta Engineering, Chantilly, Va., to integrate Tranche 0 of the NDSA. This includes integrating the Transport and Tracking Layers, hardware- and software-in-the-loop testbeds and the ground systems developed by the Naval Research Laboratory. Perspecta would also hold a capstone event to demonstrate system capabilities for potential operators.

The 20 Transport Layer Satellites, eight Tracking Layer satellites and two medium field-of-view Overhead Persistent Infrared (OPIR) spacecraft being developed by the Missile Defense Agency, are set to be deployed in two planes of 15, each with 10 Transport Layer, four Tracking Layer and one OPIR satellites, creating the initial version of the NDSA.

SDA Moves Forward With Tranche 1
With the first tranche of satellites on track, the SDA remains committed to its two-year development cycle. It has started the development process for Tranche 1, which is expected to provide initial, limited operational capabilities when it enters service in fiscal 2024.

The SDA has released requests for proposals for the Tracking Layer Tranche 1 satellites as well as the “Tranche 1 Demonstration and Experimentation System” (T1DES) satellites. The Tranche 1 Tracking Layer will include around 126 satellites across six orbital planes. Although the details have not been finalized, Tournear says that the SDA is looking at adding a third contractor to build satellites. The T1DES program will consist of 18 vehicles with experimental payloads: 12 developed by industry and six by the government.

Commercial partners are also expected to join the program over the next few years. Commercial imagery provider Capella Space announced at the beginning of the month that it would integrate optical intersatellite links on its commercial synthetic aperture radar satellites to demonstrate their interoperability with the NDSA architecture.

The SDA is also seeking to advance integration over the same period. It has released a request for proposal for Tranche 1 ground operations and integration to design, integrate and test the mission operational environment for the Tranche 1 Transport Layer.

Managing a Technological Revolution
This initial progress is not the end of the story. The Space Development Agency must still translate its concepts into operations and manage the transition to the Space Force.

Some of the problems are typical of any satellite program. The move into production and operations may result in delays that disrupt the SDA’s rapid introduction cycle and increase costs. The use of commercial satellite production lines like SpaceX’s Starlink may cut down this risk, but this remains to be proven.

Other risks are tied to the novelty of the constellation operating concept. At a programmatic level, the SDA will have to prove that it can manage the rapid development, acquisition and deployment of dozens, and eventually hundreds, of satellites. At the technology level, challenges include implementing new systems such as optical crosslinks and mesh communications and ensuring that spacecraft from numerous manufacturers maintain interoperability across several generations.

An existing challenge is the need to revamp the military’s satellite command-and-control capabilities, said Weeden, the space expert. At present, a significant number of personnel are needed to monitor a limited number of spacecraft and many satellite systems or constellations require a unique ground control segment that can't talk to other satellites. The most recent effort to update just one of those unique systems, the GPS Operational Control Segment (OCX), is years behind schedule and breached congressional cost limits in 2016. The military may need to look to the commercial sector as it grapples with the challenge of monitoring increasingly larger constellations. Otherwise, the NDSA may not reach its full potential.

The military must also manage the risk of orbital collisions. This issue has risen in importance as hundreds of small satellites have been placed in low Earth orbit. Anti-satellite weapon tests generating thousands of pieces of debris, including Russia’s recent destruction of its own satellite, have made the issue worse. Advanced command-and-control capabilities will play a part in mitigating this risk. The military must ensure that the NDSA satellites do not add to the problem by meeting international standards for the disposal of out-of-service spacecraft.

Organizational Challenges Await
Finally, the SDA will need to work with the other services to ensure the NDSA can be exploited by personnel on the ground. The military in the past has neglected the ground infrastructure needed to employ advanced space capabilities, said Weeden. The services will need to have the required radios and infrastructure to link to and take advantage of the NDSA. This will also make the constellation more relevant to the JADC2 distributed communications backbone linking sensors and shooters.

The SDA has taken steps to meet these challenges, including Link 16 data links and Integrated Broadcast System capability in its first and second generations of the Transport Layer satellites. In the future, other data links may be added to increase interoperability, such as the Multifunction Advanced Data Link (MADL) on the stealthy F-35 fighter jet.

The transition to Space Force will also need to be managed. With the changeover scheduled for October 2022, just ahead of the launch of the first Tranche 0 satellites, SDA must ensure that there are no planning or funding disruptions along the way.

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The Space Development Agency is seeking to revamp how the U.S. military takes advantage of the space domain. Since unveiling the National Defense Space Architecture, it has let contracts for dozens of Tranche 0 satellites and is on track to award work for more than 100 Tranche 1 spacecraft. It has revamped the acquisition process, giving several companies contracts to spread risk, lower costs and build interoperability.

This is a promising start, but much remains to be seen. The satellites are still being built with none yet launched. Meanwhile, SDA is managing a major organizational shift to Space Force. Unforeseen challenges are no doubt ahead. If it can navigate these disruptions successfully, SDA stands to revolutionize the space domain for the U.S. armed forces.

Note: On Dec. 16, Military Periscope and the Government Business Council will discuss the NDSA in further detail in a webcast. Click here for more information, and to register!