Europe is testing the viability of massive miles-long solar space satellites

Europe is getting serious about harvesting solar power from outer space.

As the European Space Agency (ESA) points out, the sun shines 24/7 in space, and its rays are much more intense there than when they've made their way through the Earth's upper atmosphere.

Recent studies have shown that space-based solar power could revolutionize how we harvest renewable energy. But is it commercially feasible, and could it really play a key role in the energy transition?

ESA's SOLARIS aims to prove space-based solar power works

Decarbonization will require a paradigm shift for the energy sector. It will have to rely on, in part, technologies that do not yet exist.

The ESA's Basic Activities program has conducted several studies that show space-based solar power is "workable and could support the path to decarbonizing the energy sector," the ESA's statement reads. "However, significant uncertainties and technical challenges remain," the space agency adds.

Enter SOLARIS, the ESA's newly-proposed research and development program aimed at maturing the concept and proving its commercial viability. Space-based solar power was first proposed in the late 60s by U.S. space expert Peter Glaser.

The concept would have solar power satellites in geostationary orbit harvesting sunlight at all times. These satellites would convert the sunlight into low-power density microwaves and beam them down to receiver stations down on Earth. According to the ESA, to collect enough energy, these satellites would have to be several miles in size, as would the receiving stations on Earth.

Developing the solar space farms of the future

The sheer size of the satellites required means technical advances in in-space manufacturing and robotic assembly, as well as high-efficiency photovoltaics, would be needed before any mission could get the green light.

What's more, more research is needed on the potential adverse effects of low-power microwaves on the health of human and animal populations living near any receiving station. Tests to ascertain compatibility with aircraft and other satellites are also required.

“These are the kind of technical questions that SOLARIS will look into, to explore further the feasibility of the concept, so that Europe could make an informed decision in 2025 on whether to proceed with a Space-Based Solar Power program in the future,” explains Sanjay Vijendran, ESA’s lead for the SOLARIS proposal.

“As an added plus," he added, "any breakthroughs achieved in these areas will be valuable in their own right, applicable to many other spaceflight endeavors."

In-orbit demonstrations of space-based solar power are also being prepared by the U.S., China, and Japan. In the U.K., meanwhile, the Space Energy Initiative is working on its own program. SOLARIS could play a vital role in the eventual launch of space solar power farms.