U.S. Japan Cooperation on Tactically Responsive Space: Near Term Capability and Long Term Alignment

Commentary by Benjamin Rimland

Published September 11, 2024

Among the recent raft of extraordinary changes to the U.S.-Japan alliance-including the overhaul of U.S. Forces Japan into a warfighting command, the stand-up of a Japanese Joint Operations Command, and the move toward in-country maintenance for U.S. warships based in Japan-cooperation on national security space embodies the scope of new opportunities for the alliance. Guided by a suite of strategic guidance documents and ministerial proclamations like its 2023 Space Security Initiative and the 2024 Joint Statement of the Security Consultative Committee, Japan is collaborating with the United States on large-scale national security space initiatives, including exploring concepts for a low Earth orbit (LEO) constellation of satellites for missile warning and tracking, sharing data for space domain awareness (SDA), and fostering a space subject matter expert workforce.

This cooperation in developing constellation concepts, improving Japan's space workforce, and injecting space-enabled services into the U.S.-Japan alliance exercises will pay major dividends in the next five to ten years. U.S.-Japan collaboration on a next-generation proliferated LEO constellation shows promise for a future missile warning and tracking constellation that complements the U.S. Space Development Agency's proliferated warfighter space architecture. Workforce development reforms, such as bringing more Japanese liaison officers to space operator education courses at U.S. Space Command (USSPACECOM), will help form the connective tissue between the alliance's space professionals. Japanese industry will need to work with the Japanese government, the U.S. government, and U.S. industry to prepare for the "mass production" of critical technology, as directed by Tokyo's Space Security Initiative.

However, with 2027 as the unofficial "be ready" deadline for the U.S. joint force in an Indo-Pacific contingency-and with senior Japanese officials expressing similar feelings of urgency-longer-term reforms to strengthen defense space cooperation must come in tandem with near-term projects to build greater alliance capacity for critical space missions and ensure that Japan's military space culture keeps pace with its U.S. ally. U.S.-Japan collaboration on the Tactically Responsive Space (TacRS) initiative will build greater short-term capacity for critical space missions for the alliance and also inculcate a cultural shift within the Japanese space industry and government institutions that rewards agility.

U.S. Department of Defense (DOD) budget documents state that TacRS "rapidly integrates and deploys space-based end-to-end capabilities in response to Combatant Commander (CCMD) urgent needs" with capabilities that "are planned to enter operations and generate effects within 24 hours of tasking." The documents further state that the TacRS program will demonstrate "initial operational capabilities," commencing in FY 2025. The 2023 TacRS mission VICTUS NOX saw Firefly Space launch a Millennium Space Systems SDA payload on its small-lift Alpha vehicle to orbit within 27 hours of receiving the order, and Rocket Lab and True Anomaly will team up to support the VICTUS HAZE mission, which the Space Force is looking to compress into an even faster timeline. Both the VICTUS HAZE and VICTUS NOX missions focus on rapidly deploying on-orbit capability to perform rendezvous and proximity operations and characterize an unknown object on orbit-what the budget documents term Space Domain Awareness and Combat Power.

To achieve faster timelines, the VICTUS missions leverage smaller rockets like the Firefly Alpha or Rocket Lab Electron and payloads able to be mated to the launch vehicle within hours of an execution order-a feat yet to be demonstrated by conventional, larger rockets. These missions also accelerate satellite and launch vehicle checkout and ground infrastructure support processes and are leading to the development of new operational concepts, training, and tactics for rapidly deploying space capabilities to meet warfighter needs. The DOD budget documents further note that "activities that may leverage . . . international opportunities" will be an element of FY 2025 plans for TacRS. TacRS is as much about cultural shifts as it is about developing new capabilities.

Japanese providers are developing launch and on-orbit capabilities similar to those exhibited in prior VICTUS missions. The Japanese government already flies a rocket of a similar size, shape, and thrust capacity to Firefly Alpha known as Epsilon. But unlike the Alpha and Electron rockets that rely on cryogenic propellants, Epsilon uses a solid propellant, which obviates the need for lengthy loading of liquid oxidizer. The Japanese Aerospace Exploration Agency is refining the next-generation Epsilon-S model. The Japanese private company Space One is developing a solid-fuel rocket known as Kairos, which on its first unsuccessful test launch carried a small intelligence-gathering satellite aimed at demonstrating Japan's space service augmentation capabilities. When fully proven, Epsilon and Kairos may be able to offer additional TacRS capability-along with easier transportability due to their solid-fuel design. Kairos is geared more toward small satellites (150-250 kg to LEO), while Epsilon-S will offer capability similar to Firefly Alpha (600-1400 kg to LEO).

Japanese satellite manufacturers like Astroscale have designed and launched debris removal satellites capable of on-orbit SDA and remote proximity operations, and the Japanese government will expand its Space Operations Group to further develop its SDA capabilities. The Japanese government has long collaborated with private-sector satellite communications (SATCOM) operator SKY Perfect JSAT for military SATCOM and is working to develop further resiliency in X Band SATCOM for defense uses.

Encouraging the Japanese government and industry to participate in a bilateral, VICTUS-like mission could be a near-term space partnership for the U.S.-Japan alliance that would field practical capabilities for warfighters. In the short term, Japan could launch and operate its own SDA capability that will meet a need communicated to the Japanese government and industry by the U.S. Indo-Pacific Command or USSPACECOM. This would ensure that Japan can learn by practicing the tactics, techniques, and procedures exhibited by the TacRS initiative while also providing an immediate capability to meet U.S.-Japan alliance needs. The mission could manifest as a component tied into larger bilateral alliance field training exercises like the Keen Sword series. With U.S. Space Forces Indo-Pacific already participating in the command post-Keen Edge exercise, the incorporation of a VICTUS-like mission into Keen Sword could refine alliance tactics, techniques, and procedures for surging critical space domain awareness services that might be disrupted during a contingency.

In the longer term, Japanese participation in a VICTUS-like TacRS mission could also come in the form of launching an Epsilon-S or Kairos rocket carrying a Japanese satellite that complements U.S. defense space architectures, like a Japanese SATCOM payload. Incorporating the effort into Keen Sword could craft a realistic scenario for surging SATCOM during a high-end conflict, which would involve pushing Japanese industry and government to work closely with U.S. counterparts to swiftly modify a commercial capability, ready ground infrastructure, and rapidly launch the payload to meet an emergent alliance need. The effort would boost the broader U.S.-Japan alliance space enterprise and its workforce and jointness reforms, including Japanese liaison officers at USSPACECOM, U.S. Space Forces Indo-Pacific, and Japan's space operations group.

Over time, U.S.-Japan cooperation on TacRS will also help develop a Japanese national security space culture that rewards greater speed and aligns with a key objective of the U.S. Space Force. U.S. Space Force leaders have clarified that TacRS is more than simply a rapid launch-it is a shift in cultural mindset among industry and warfighters alike that space can no longer be measured in long timelines to design exquisite solutions, but must be considered on a "tactically relevant timeline." This translates into novel concepts of operations, such as military leaders directing commercial satellites and swift repurposing of off-the-production-line satellites.

A bilateral VICTUS exercise would subject Japanese industry and the government to the same sorts of competitive pressures facing U.S. participants in the VICTUS missions-no-notice launches, modifications of off-the-line systems for emergent missions, rapid payload check-out and mating, and hand-in-glove collaboration between military and industry. Japan will benefit by developing an industrial and government culture for national security space that moves quickly to meet tactical needs, while the United States will benefit by developing the capability of its ally to the point where Japanese capabilities can complement U.S. space missions and systems.

The U.S.-Japan alliance's growth into bilateral space cooperation must balance longer-term efforts to build interoperable systems, ground architectures, and workforce development with projects like TacRS cooperation to generate lasting cultural shifts and further deliver near-term capability to match the urgency of the Indo-Pacific security situation. With Japanese industry preparing to expand space manufacturing amid Japan's rapid national security space budget buildup and Japan's defense ministry developing its space workforce, U.S.-Japan government-to-government and industry-to-industry collaboration on TacRS can build near-term capability and solidify long-term cultural shifts. The near-term alliance capability benefits and longer-term cultural alignment will benefit both allies and generate a deterrence signal to adversaries looking to disrupt or deny U.S. or Japanese access to space-enabled services. Bilateral TacRS collaboration will also develop the SDA capabilities of the allies to better keep a watchful eye on what adversaries are doing on orbit. As Japan and the United States take further steps to "train as they fight," adding TacRS to the current roster of bilateral training supplements alliance efforts to practice multi-domain joint operations in an environment in which space-enabled services may be denied or disrupted.

Benjamin Rimland is a fellow with the Aerospace Security Project at the Center for Strategic and International Studies in Washington, D.C.

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