Zhai Jiachen, Xie Hao, Zhao Haoxiang, Li Guowen
On February 4, 2024, the U.S. Space Development Agency and the U.S. Missile Defense Agency launched six artificial satellites into Earth orbit, including two HBTSS (Space Sensors for Hypersonic Missiles and Ballistic Missiles) satellites designed to track hypersonic and ballistic missiles, as well as other complex air targets, and four PWSA (Augmented Combat Force Space Architecture) satellites. According to Frank Turner, Technical Director of the Space Development Agency, the HBTSS and PWSA satellites will be the first to be able to directly control ground-based weapons systems. The successful networking of the US HBTSS and PWSA satellites may mean that in the eyes of the United States, the missile's whereabouts have been exposed.
HBTSS - a monitor for hypersonic weapons
The predecessor of HBTSS, the hypersonic and ballistic tracking space sensor that the U.S. Missile Defense Agency is working to build, is an in-orbit sensor layer capable of detecting and tracking hypersonic weapons that the country's current missile defense architecture cannot handle, and the system is planned to be built into the space agency's constellation of low-Earth orbit satellites. The HBTSS (Hypersonic and Ballistic Tracking Space Sensor) project aims to develop a powerful, affordable, survivable, and scalable space sensor to detect and track advanced weapons such as hypersonic missiles.
Fig.1 Conceptual diagram of the HBTSS system satellite
The HBTSS system consists of about 200 sensor payloads of 50-500 kg deployed on low-orbit commercial satellites. After the deployment of the system, the first is to make up for the lack of early warning and detection capabilities for hypersonic weapons, and form a full-process tracking capability for hypersonic weapons; Second, it can cover the active stage of missiles together with the "space-based infrared system" and the next-generation "overhead continuous infrared" system, so as to enhance the early warning capability of advanced ballistic missiles. The system is planned to be tested and verified in space-based demonstration tests from 2021 to 2022, and will be deployed and operated after 2025.
Fig.2 ABM system consisting of HBTSS
The US Missile Defense Agency launched the development of the HBTSS satellite in 2018, and L3Harris Technologies Inc and Northrop Grumman were chosen as the developers and creators of the satellite. It is expected that the entire HBTSS satellite constellation should be deployed by the end of 2026 and will allow tracking the entire flight of hypersonic and ballistic missiles, from launch to destruction with interceptor missiles. Such capabilities will allow the anti-missile defense (ABM) system to launch anti-missile missiles even before the target enters the radar coverage area. This capability means that the United States will not be threatened by weapons such as hypersonic missiles in future wars. Just imagine, a hostile country has just launched a hypersonic missile, and the US HBTSS system in space has already locked on to this missile, calculating its trajectory at all times, and it can be easily intercepted. Even if the target of this missile is not the United States, they can still monitor it.
PWSA – A Rigorous Space Combat Structure
The U.S. Space Development Agency (SDA) is preparing to build a new military constellation based on space technologies such as the Link16 datalink demonstration satellite, laser link, Project Blackjack, and commercial remote sensing satellites, which is called the "Defense Space Architecture", later renamed the "Proliferative Combat Unit Space Architecture" (PWSA), which integrates multiple functions such as communications, monitoring, tracking, navigation and situational awareness, with most satellites in LEO orbit and a small number in medium and high orbits.
Fig. 3 Schematic diagram of the spatial distribution of PWSA
U.S. Space Development Agency Administrator Tunier said the name change to better reflect the network's network characteristics, and the core mission of launching space payloads into orbit as quickly as possible has not changed. A "proliferated warfighter space architecture" is not only harder to target by adversaries, but also accelerates the delivery of space capabilities; The 28 initially configured Tranche 0 satellites will be launched in two phases in March and June 2023; The 174-unit Tranche 1 satellites will begin launching in September 2024, with a total of 10 launches, almost once a month. The development of the ground system is also well underway, with two major network and operations centers located at Army Redstone Arsenal in Alabama and Grand Forks Air Force Base in North Dakota, as well as about a dozen ground stations around the world for downlink data transmission.
The PWSA system can be divided into seven layers, namely the transmission layer, the tracking layer, the navigation layer, the hosting layer, the deterrence layer, the combat management layer, and the support layer. The transport layer houses a Ka-band space-to-ground communication link, four optical communication terminals, a Link16 payload, and a combat management, command, control, and communications (BMC3) computing storage module. The tracking layer will be equipped with infrared sensors to detect and track missile threats, and it will also be able to track hypersonic vehicles. The navigation layer itself is not actually a constellation, nor is it intended to replace GPS, it is an additional capability formed by the transport layer satellites, but it does play a role in navigation. Due to the nature of a mesh network that covers the entire world, transport layer satellites will be able to transmit precise position, navigation, and timing (PNT) data. The hosting layer has intelligence, surveillance, and reconnaissance (ISR) capabilities, with ISR satellites detecting and tracking ground targets. In addition to launching its own constellation of hosted layers, the SDA will integrate commercial satellites that already collect sensing data, as well as spy satellites operated by the National Reconnaissance Bureau and other intelligence agencies.
Figure 4 The seven levels of PWSA
The deterrence layer can provide space situational awareness, detect and track space objects, and avoid satellite collisions. In addition, it will also develop key vehicles to monitor the Earth-Moon space and advance the space military to a wider space. The combat management speaks of the payload carried by each transport layer satellite, the use of computers to dynamically manage the satellites and the interaction between the layers. This layer will be hosted on most satellites and will be responsible for processing data in orbit (or "edge computing"). The support layer contains ground command and control facilities and user terminals to provide rapid response and launch services.
Cooperate in networking to achieve full monitoring of deterrent weapons outside the original architecture
The HBTSS and PWSA satellite programs write that "they should detect hypersonic and ballistic missiles, as well as other types of targets." Compared with the original defense architecture, the structure and function of the HBTSS and PWSA satellite networking not only supplement the lack of hypersonic missile and ballistic missile monitoring and defense capabilities in the original defense monitoring architecture, but also make people think about other types of targets mentioned therein.
It is reported that the HBTSS and PWSA satellite systems were initially sharpened not only for strategic complexes, such as ICBMs or hypersonic gliding warheads of the Avangard type, but also for operational-tactical missiles (for example, Zircon, Kinzhal, etc.). But if this is the case, then the HBTSS and PWSA satellite networks will definitely see Iskander missiles, Kh-22 and Kh-32 aeroballistic missiles, anti-ship missiles (ASM) of the Onyx, Granit, Bazalt and Vulcan types. And this also means that in the eyes of the United States, the opponent's missiles have just been launched, and they will have an unobstructed view in their eyes, and the trajectory of their movements will have been completely captured outside the reconnaissance range of the ground radar station.
Figure 5 The HBTSS and PWSA satellite systems are conducting missile reconnaissance
It can be seen from the above that the United States has not only actively attached importance to military development in the field of space, but has also achieved remarkable results. Under the HBTSS and PWSA satellite systems, the whereabouts of hypersonic and ballistic missiles and other missile orbital weapons outside the original surveillance defense system will be exposed. Obviously, the successful networking of HBTSS and PWSA satellites will give the United States an opportunity to win the first place in the war, or it will lead to a global upsurge in the development of space militarization.