As both the demand for and deployment of non-terrestrial communications networks (NTNs) accelerate on a global basis, aerospace and material science company Sceye, a specialist in high-altitude platform systems (Haps) for telecommunications and real-time environmental monitoring, has announced the successful trans-Pacific flight of its Service Test 1 (ST1) mission from New Mexico to Japan, demonstrating mobile broadband connectivity to unmodified devices
Conducted in partnership with Japanese and global telecommunications operator and IT business SoftBank, ST1 marks Sceye’s first flight to Asia, and what the latter says is a groundbreaking milestone towards the commercial deployment of Haps as stratospheric infrastructure.
Sceye noted that the stratosphere offers an optimal vantage point: it is close enough to Earth for high-capacity connectivity and observation, yet the altitude is high enough for wide-area reach. Importantly, it added, the stratosphere offers space-like conditions without the cost of being in space and the disadvantages of being in orbit.
Sceye’s Haps maintain altitude and their area of operation in the stratosphere through consecutive day and night cycles, operating like geostationary satellites, only 1,800 times closer to Earth and at a fraction of the cost.
In 2025, SoftBank invested in Sceye’s Haps-based stratospheric infrastructure as a scalable offering to complement terrestrial towers and satellite constellations. The strategic partnership is said to advance a shared vision for Haps and NTN as transformative infrastructure that can expand connectivity, support communications during disasters, and enable future applications across artificial intelligence (AI), the internet of things, aerial communications, edge computing and 6G.
In its mission, which began on 13 August, ST1 travelled more than 15,000km through the stratosphere in 13 days, and upon arrival over Japan, used SoftBank’s core network as well as Haps-based edge computing and communication with drones to support the development of a 3D communications network.
It operated at approximately 16.5km in altitude while completing telecommunications, drone and emergency communications. It is also said to have confirmed communications performance equivalent to that of terrestrial networks while reducing radio interference with ground-based base stations.
ST1 carried SceyeCell, a first-of-its-kind “cell tower in the sky” designed to deliver wide-area mobile broadband directly to standard devices from the stratosphere. When deployed at full scale, one Sceye Haps is designed to cover the equivalent area of approximately 500 terrestrial towers. Applications supported included text messaging, voice calls, internet access and video streaming, while testing also included emergency calls, using an emergency alert messaging system designed for large-scale disasters, and communications with drones.
Through a server installed on the Haps, Sceye and SoftBank conducted data processing directly on the platform, with average round-trip processing response time of 68 milliseconds, reducing communications latency by over 40% compared with internet-based cloud processing.
Sceye and SoftBank said the demo marks the world’s first successful test in which a mobile core network and a web server for processing were installed on a Haps, enabling response processing to be performed entirely onboard the Haps with the results to be relayed back to smartphones.
“This flight marks a defining moment for Sceye and for the commercial potential of Haps,” said Sceye founder and CEO Mikkel Vestergaard Frandsen. “Flying from the US to Japan demonstrates the performance required to make the stratosphere a viable layer of infrastructure and realise the future of AI, edge computing and 6G. Together with SoftBank, we are moving beyond proving the technology to demonstrating how Sceye can complement and extend existing networks and deliver persistent connectivity at scale.”
SoftBank president and CEO Junichi Miyakawa added: “The fact that Sceye’s Haps reached Japan from the US and successfully provided Japan’s first trial services from the stratosphere in Japan’s airspace marks an important step toward the commercialisation of Haps, which is at the core of this vision.
“By combining the Haps flight and operational technologies that Sceye has developed with SoftBank’s communications technologies, we have gained confidence to realise a three-dimensional communications network utilising Haps. Going forward, in collaboration with Sceye, we will continue to integrate a wide range of technologies, including communications and AI, to develop Haps into a new form of social infrastructure.”
The flight builds on Sceye’s Endurance Program, completed earlier in 2026, when its SE2 Haps travelled more than 10,000km in the stratosphere from New Mexico to the coast of Brazil, where it stayed over its area of operation for several days to test long-duration performance in preparation for the Service Test Program, the first of which flew to Japan. ST1 remains in flight, returning towards the US over the Pacific Ocean.
