The satellite, no bigger than a washing machine, is scheduled to launch later in 2026 into orbit roughly 400 kilometers above Earth. Once operational, it will transmit energy wirelessly to a 13 antenna receiving station in Suwa, central Japan. The initial output will be modest, about one kilowatt, enough to power a coffee maker, but the test aims to prove that space based solar power actually works. If successful, Japan plans to scale up to a one gigawatt orbital solar array within 25 years, enough to power hundreds of thousands of homes.
In space, sunlight is constant. No clouds, no nightfall, no atmospheric interference. Solar panels in orbit can collect energy uninterrupted, 24 hours a day.
OHISAMA (Japanese for “sun”) will carry a two-square-meter solar panel and weigh roughly 400 pounds. Once in low Earth orbit, it will convert sunlight into microwave energy and transmit it toward the ground station covering 600 square meters in Suwa. The challenge is precision. The microwave beam must be directed with an angular error of less than 0.001 degrees while the satellite circles Earth at more than 17,000 miles per hour, targeting a fixed point on the ground. Even slight deviation means lost energy or scattered radiation.
That level of precision has only become feasible through recent advances in microwave transmission, lightweight materials, and lower launch costs driven by private space companies.
Japan imports more than 90 percent of its energy. After the Fukushima Daiichi nuclear disaster in 2011, the urgency to find reliable, non nuclear alternatives intensified, making orbital solar collectors particularly attractive. They offer something rare: energy independence that is both renewable and scalable.
Japan’s geography adds complexity. Large scale solar farms require land, and Japan has limited space with a population concentrated in urban areas. The Japan Aerospace Exploration Agency has supported wireless power transmission research for decades, with early experiments in the 1980s and 1990s demonstrating basic feasibility. Since 2009, the government’s national space policy has formally included space solar power as a development goal. This is not an overnight idea, it represents years of steady groundwork.
Japan is not alone in this pursuit. The United States tested space solar power with NASA’s PRAM experiment in 2020 and Caltech’s MAPLE demonstration in 2023, which successfully transmitted power wirelessly in orbit. China also announced plans for space solar power stations, with targets for kilometer scale arrays by the 2030s.
Each project tackles different technical challenges — efficiency, beam safety, transmission accuracy —  all while sharing the same goal: building an orbital layer of clean energy infrastructure. The potential advantages are significant. Unlike terrestrial solar farms, orbital collectors would not be affected by weather or daylight cycles, allowing them to supply continuous renewable energy to disaster prone regions or areas with weak infrastructure.
 
A 2021 NASA study suggested space solar power could cost up to ten times more than land based solar or wind energy, with launch costs, satellite construction, maintenance, and transmission losses all adding up. Public concerns about transmitting microwaves through the atmosphere persist, though research indicates no harmful effects at operational power levels. The microwave frequencies used are similar to those in Wi-Fi and cellular networks, and the beam intensity at ground level would be comparable to sunlight.
For now, OHISAMA remains a test, small in scale but significant in ambition. The satellite will demonstrate whether the technology can function reliably in orbit and whether wireless power transmission can work at meaningful distances. If Japan succeeds, the one kilowatt signal from a satellite above Suwa will prove that harvesting solar energy in orbit and delivering it wirelessly to Earth is technically viable, marking progress toward a future where orbital solar arrays complement terrestrial renewable energy systems.
The test won’t settle the economic questions or eliminate concerns about cost and scalability, but it will prove whether the underlying engineering functions, an essential first step.

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