B. On-Orbit Services R&D on Space Solar Power Systems (SSPS)

A Space Solar Power System (SSPS) collects solar energy in outer space, converts it into a microwave or laser beam, transmits that energy to Earth, and converts it into electrical power.

Often described as a “power plant in space," it is expected to serve as a form of renewable energy that helps address global challenges such as energy supply, climate change, and environmental issues.

JAXA is researching a wide range of enabling technologies, including wireless energy transmission by microwaves and lasers, large-scale space structure construction, space solar cells, and debris mitigation technologies, with the aim of practical application in the latter half of the 21st century.

Significance of the Research

SSPS offers the following advantages:

Low carbon dioxide emissions and minimal exposure to fossil fuel price fluctuations.
Access to solar radiation is about 1.4 times stronger than at Earth’s surface, providing a stable energy source largely unaffected by day–night cycles or weather.
Flexible wireless delivery of power to where it is needed, reducing dependence on terrestrial power grids.
Lower vulnerability to ground-based natural disasters such as earthquakes.

Realizing SSPS, however, requires overcoming many technical, safety, and economic challenges:

Highly efficient and safe power generation, transmission, and reception
Construction of large-scale space structures
On-orbit operation, maintenance, and repair over the long term
Mass, low-cost transportation to space

Research Objectives

Microwave Wireless Power Transmission Technology

R&D on the technologies essential for transmitting energy from space to Earth by microwaves, including high-efficiency power-to-microwave-to-power conversion and precise beam control.

Laser Wireless Power Transmission Technology

R&D on the technologies essential for transmitting energy by laser beams, including high-efficiency conversion and precise beam propagation control.

Large Space Structure Construction Technology

As a first step, R&D focused on establishing unmanned assembly technologies for structures ranging from tens to hundreds of meters in scale.

About the SSPS

Many studies have been conducted on SSPS concepts and technologies in Japan and overseas. The section summarizes the history, advantage, and challenges of the SSPS.

FAQ

Answers to the questions most frequently asked about the SSPS program.