Solar Power Satellites and WPT

What are solar power satellites or space-based solar power stations?

The concept of space-based solar power uses the wireless transmission of solar energy collected in space by solar power satellites, for use on Earth, on the Moon or on other planets. Solar power satellites can benefit from higher solar illumination, unfiltered by atmospheres, or even permanent sunlight in some orbits. They therefore offer the possibility to transmit clean energy, in a flexible way, to different remote users in space, on Earth or on the surfaces of the Moon and Mars.

In the long term, solar power satellites have the potential to mitigate climate change through the provision of clean energy. Earlier applications might be in space, for example to support exploration of the Moon and Mars. Compared to energy collection on the surface of a planet, a satellite’s solar collectors have the benefit of being unobstructed by a planet's atmosphere or local topography and can operate independently of a planet's tilt or rotation.

This concept was first described by Tsiolkovsky 100 years ago and first proposed as an engineering concept by Glaser in 1968. The development of various technological building blocks has progressed since then, and over the years many approaches to SPS technology have been proposed, from mirror satellites(1)(2)(3), to microwave beaming(4)(5), to laser technologies(6) To date, only select subsystems have been realized(7), but more and more solutions are being proposed for the near- to mid-term(8)(9)(10)(11). 

Why are solar power satellites not yet a reality?

Solar power satellites are by design relatively large structures and require advances in a number of key technical areas that push the boundaries of what is currently feasible in space. Some of these current technological bottlenecks include, but are not limited to:

• Very large structures (manufacturing, deployment)
• Construction (materials, modularity, in-orbit manufacturing, robotics...)
• Power generation and onboard energy conversion (high voltages, efficient solar to electric and electric to microwave/laser conversions)
• Thermal systems (efficient large radiators and distributed thermal subsystems)
• Wireless power transmission systems (laser/microwave generation, control, focusing, pointing...)
• Microwave/laser to electric conversion at receiving site(s)
• Operations (station keeping, autonomy, safety, resilience and redundancy, maintenance and servicing, re-fuelling including with in-space resources)
• Control (structures, formations, wireless power transmission beams)