Japan’s Stratospheric Communications Layer
Can sovereign HAPS close the resilience gap between terrestrial networks and military satellites?
On 29 May 2026 the Japanese Ministry of Defense announced that it had concluded a contract for a project titled Research Study Necessary for Domestic HAPS, awarded to Space Compass Corporation on 24 February 2026 for ¥238,761,710 including tax, with performance running to 30 March 2028. Set against the acts that frame it, the sum is small and the timetable is long. The Defense Buildup Program approved on 16 December 2022 commits approximately ¥43 trillion over the five years from FY2023 to FY2027 and instructs the Ministry to establish multiple layers of communication band with higher resiliency in addition to conventional X-band communications. The consortium in which the contractor sits committed USD 100 million to a single foreign platform manufacturer in June 2024. What the Ministry has bought is therefore not a capability but a filter, and the structural constraint it exists to test is stated in the specification itself: current foreign-made high-altitude platform stations are not optimised for Japanese sunlight and weather conditions and are subject to take-off and landing constraints, so an airframe capable of year-round operation in the Japanese stratosphere does not yet exist. The unresolved question is what a state does when a capability it has designated as necessary to its communications resilience cannot be bought in a form its own airspace and climate will accept, and when the only firm with the flight record to study the problem holds that record through an aircraft it does not build.
The first section reads the strategic and institutional architecture against three adopted instruments — the Defense Buildup Program, the Space Domain Defense Guidelines of July 2025 and the Next-Generation Information and Communication Strategy of the same date — and establishes where the stratosphere sits in a layered network running from the ground to geostationary orbit. The second works through the procurement mechanics: the tender notice and specification issued on 14 January 2026, the four qualification conditions, the required outputs and reporting schedule, the identification of the 1,710–1,980 MHz, 2,010–2,025 MHz and 2,110–2,170 MHz bands for high-altitude platform stations as IMT base stations in the Final Acts of the 2023 World Radiocommunication Conference, and the Japanese civil-aviation regime governing flight above 150 metres under the Civil Aeronautics Act. The third examines industrial and technological structure through the corporate record of Space Compass, its shareholders and partners, the NICT commissioned research programme numbered 07702, the NTT and DOCOMO technical literature on relay and base-station payload architectures, and the flight and certification record of AALTO’s Zephyr and SoftBank’s Sunglider. The fourth sets out what follows for procurement and for industrial policy. This report does not value any company, does not project the outcome of the study, and does not treat a research contract as evidence of a programme of record.