SoftBank Corp. Completed Japan’s first stratospheric mobile base trial over Kochi Prefecture. The platform transmitted voice, video and drone control signals from an altitude of 20 kilometres.
The uncrewed, airship-like craft can hover for up to six months. It acts as an airborne cell tower when earthquakes or typhoons knock out ground networks.
Stratospheric Flight Over Kochi
Crews launched the High Altitude Platform Station craft from New Mexico. They ran communication tests above western Japan’s Muroto region on August 23 and August 24. Engineers confirmed stable two-way voice, video and emergency channels during the two-day window.
Flight trials also maintained continuous control links with inspection drones. SoftBank plans to deploy those links during natural disasters to check damaged roads and assess collapsed buildings without risking ground survey crews.
Rival Operators Test Disaster Links
Japan’s three dominant carriers are competing to secure non-terrestrial coverage across an archipelago exposed to frequent seismic activity. SoftBank, NTT DOCOMO and KDDI Corp. Already sell direct-to-satellite messaging for smartphones. Satellite bandwidth, however, struggles to support video feeds and autonomous drone flights during emergencies.
High-altitude stations solve that bottleneck by operating closer to Earth than low-orbit satellites. NTT DOCOMO is preparing trials in Ishikawa Prefecture’s Noto peninsula using a balloon-shaped craft. That project targets damage assessments and labor monitoring for forestry and agriculture.
Commercial Service Targets 2027
Demand for stratospheric networks intensified after a magnitude 7.6 earthquake struck the Noto region on January 1, 2024. The disaster cut road access and severed terrestrial fiber links across dozens of coastal communities.
SoftBank plans to widen flight zones and extend mission durations ahead of a commercial rollout in 2027. That service will target enterprise clients and municipal governments seeking backup connectivity during regular operations.

