Sceye and SoftBank complete 15,000 km stratospheric test flight

The ST1 mission reached Japanese airspace on September 1, 2026, operating at an altitude of approximately 16.5 kilometers. During the test, the craft maintained a station-seeking radius as tight as 5 kilometers while integrating with SoftBank Corp.’s core network. This allowed for standard mobile functions, including voice calls, video streaming, and emergency alert messaging, demonstrating a potential alternative to terrestrial infrastructure.

Beyond basic connectivity, the flight achieved a technical breakthrough by hosting a server directly on the platform. This onboard processing yielded a 68-millisecond round-trip response time, cutting communication latency by over 40% compared to traditional cloud-based processing. The test confirmed that a single Sceye unit could theoretically provide coverage equivalent to 500 terrestrial base stations. Both companies view this as a critical step toward integrating stratospheric platforms into global 6G and AI-driven communication networks, positioning the technology as a scalable tool for disaster response and rural connectivity.