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Japan intends to set a record in renewable energy technology by sending OHISAMA a demonstration satellite into orbit to figure out if solar energy generated in space. Also, it will check if the solar energy will be transmitted back to Earth and converted into usable electricity. If the mission is successful, it will be the first time space, based solar energy is delivered and effectively utilized on the ground.
The initiative being undertaken by Japan Space Systems (J, spacesystems) with the support of the Ministry of Economy, Trade and Industry (METI) is planned to be launched in the fiscal year 2026 on board Space One’s Kairos 5 small rocket.
A Bold Step Beyond Earth-Based Renewables
Space, based solar power (SBSP) concept refers to launching huge solar panels into space from where they can continuously gather sunlight without being affected by clouds, weather, or the day, night cycle. The electricity produced onboard is first changed into microwaves (or in the future, possibly lasers) and then these are sent to Earth without any physical connection.
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On the ground, a receiving station, called a rectenna, changes the microwave energy to electricity again and thus it can be delivered to the grid.
Unlike terrestrial solar and wind systems, SBSP offers several theoretical advantages:
Continuous power generation
Immunity to weather fluctuations
Adjustable transmission to different regions
Potential disaster-response flexibility
Japan has made SBSP one of its long, term R&D priorities under the Basic Energy Plan.
They have outlined it as a possible mainstay of future energy security.
The OHISAMA Demonstration: Small Satellite, Big Ambition
The OHISAMA satellite weighs about 180 kilograms and has an integrated solar generation and transmission panel of 70 cm by 2 meters.
Its maximum output is quite small only around 720 watts but the main purpose is to provide proof of concept and not to produce energy at a large scale.
The experiment will attempt to beam microwave energy from an orbit of roughly 450 kilometers to a 64-meter parabolic antenna at JAXA’s Usuda Deep Space Center in Nagano Prefecture. The immediate objective is symbolic yet critical: using the received power to light an LED on Earth.
The orbit, to, ground experiments previously only detected signals that were transmitted from orbit, however, this mission plans to demonstrate the actual energy delivery and usable power conversion, a milestone that global competitors have not yet achieved.
The test will also assess the effects on transmission efficiency of factors such as distance, atmospheric interference, and ionospheric conditions.
The Gigawatt Vision: Scaling to Grid-Level Power
J-spacesystems’ long-term architecture is far more ambitious. The organization has outlined a future design involving:
2.5-kilometer-square solar arrays in geostationary orbit (36,000 km altitude)
Microwave transmission to a 4-kilometer-wide ground antenna
An output of approximately 1 gigawatt per unit
To put that into perspective, a single SBSP system at that scale could theoretically supply more than 10% of Tokyo’s annual electricity demand.
The key technical hurdle lies in precision. Microwave beams naturally spread due to diffraction, requiring extremely large transmission apertures and advanced phase control. Japan has developed extensive expertise in retrodirective beam control, where a pilot signal from the ground enables the satellite to automatically steer energy precisely toward the receiver.
Global Competition Intensifies
SBSP was first proposed in the United States in the 1960s, and interest has resurged amid decarbonization efforts.
Recent milestones include:
Caltech’s 2023 demonstrator, which transmitted power in space and detected faint microwave signals on Earth — though without delivering usable electricity.
Active China, U. S. , and Europe programs are already underway, and defense agencies are also thought to be looking into potential uses.
However, Japan has been carrying out research on SBSP since the 1980s and has gradually improved key technologies, such as:
High-precision microwave beam steering
Integrated generation-and-transmission panels
Improved electrical-to-microwave conversion efficiency
According to J-spacesystems leadership, Japan currently holds a technological edge in several of these enabling components.
Beyond Earth: Lunar Power and Space Infrastructure
If OHISAMA succeeds, follow-up missions would likely focus on higher output levels and longer-duration demonstrations, with commercialization targeted for the 2040s.
Longer term, SBSP could extend beyond terrestrial energy supply. Orbit-based power stations may support:
Lunar exploration missions
Space infrastructure
Remote or off-grid regions on Earth
In theory, SBSP systems could deliver up to 10 times more annual energy output than ground-based solar, primarily because they operate without weather or nighttime limitations.
Launch Risk and National Strategy
The mission’s timeline depends on Space One’s Kairos rocket, which has faced setbacks after two unsuccessful launches. Attention is currently focused on the upcoming Kairos 3 flight.
Despite overseas launch alternatives, the team opted for Kairos to align with Japan’s national strategy of strengthening domestic commercial launch capabilities.
なぜ重要なのか
If OHISAMA manages to beam power from orbit and successfully convert it into usable electricity on Earth, Japan would secure a landmark achievement in clean energy innovation.
More importantly, it would validate a concept that could reshape the future of global power generation — shifting part of humanity’s energy infrastructure beyond the atmosphere.
Whether SBSP becomes commercially viable remains a long road ahead. But with OHISAMA, Japan is aiming to take the decisive first step.
日本語