Is it time to turn on the dimmer for space solar power?

The idea of sending energy from space to the energy-hungry Earth has been explored for a long time. It was first proposed over 80 years ago in science fiction.

“All was silent in the officers’ quarters of Solar Station 5 – except for the faint murmur of the mighty Beam Director somewhere far below,” wrote renowned author Isaac Asimov in his April 1941 short story “The Reason,” which appeared in Astounding Science Fiction magazine ” .”

Asimov had his heroes in charge of a solar energy collection station in space that directed beams of energy to receivers Earthbut also Mars. Fast forward to the 21st century, and research here on Earth and now in space clearly supports this idea. Still, space Radiating solar energy is seen by some as a truly distant and unconventional technology, an economically dubious concept that would make for good science fiction. Space.com reached out to several technologists to ask what’s new, what’s old and what’s still missing when it comes to transmitting energy to Earth from space.

Related: Scientists have sent solar energy from space to Earth for the first time in history

Technology trio

Caltech’s Space Solar Power Project (SSPP) is seen by some as a ray of hope for the technology.

More than a year has passed since the SSPP technology demonstrator was launched into a test basket in Earth orbit. Once in orbit, the SSPD-1 spacecraft tested three technological innovations designed to help bring the space solar energy needle closer to full reality. They were:

BUCKS: An orbit-deployable ultralight composites experiment to demonstrate a novel packaging and deployment scheme.
ALBA: 32 different types of photovoltaic (PV) cells to assess their resistance to harsh space conditions.
CLONE: A low-orbit microwave power transfer experiment system based on custom integrated circuits with precise timing control to selectively focus power on two different receivers to demonstrate wireless power transmission over a distance in space.

a drawing of an early century scientist in a laboratory researching something.

Isaac Asimov, in his April 1941 story “The Reason,” envisioned power-emitting plants in space. (Photo by Rey Isip, courtesy of Luminist Archives/READITFREE.ORG project)

Take it to the limit

“A lot of things worked, and the ones that worked well, we pushed them until they stopped working,” said Ali Hajimiri, co-director of the Caltech Space-Based Solar Power Project.

Hajimiri focused on integrated circuits and their applications in various disciplines such as biotechnology, communications and sensing, which cover a wide range of frequencies from high-speed and radio frequencies to high-precision low-frequency circuits.

Yes, Hajimiri noted, there were some problems during the nine-month SSPD-1 mission. “We literally had a placement problem, but the team dealt with it. Even when transmitting energy wirelessly, various situations occurred. Then we really taxed the system towards the end of the mission – to the point where we were actively trying to do damage.”

Realization on the roof

a man against the background of a dimly lit wall holds a transparent sheet with an orange mesh in front of a brightly lit circle.

Ali Hajimiri, co-director of Caltech’s space solar energy project. (Photo: Caltech/Francesca Forquet)

On May 22, 2023, the payout from SSPD-1 literally hit the roof of the Gordon and Betty Moore Engineering Laboratory at Caltech. For just 90 seconds, the MAPLE equipment on the spacecraft transmitted energy collected in space to Earth.

Hajimiri quickly explains that the level of energy received at roof level was very low. He said it was mostly about detection, but the real buzz is considering the modest amount of energy received as one small step for space solar energy.

SSPD-1 will soon be decommissioned and left to sink destructively Earth’s atmosphere.

The project’s focus is now on solving problems such as scaling up, enabling autonomous deployment, and developing lighter structures.

The unknown unknowns

“There are many ‘unknown unknowns’ that still need to be unraveled,” Hajimiri said. At this stage of work, the team is looking at the production processes of cheap fabric-like systems. Additionally, timing synchronization is quite difficult, especially with a flexible, floppy disk structure floating in space.

“We have developed new ways of thinking about this problem,” Hajimiri added, “ways in which the board can determine its own shape and make corrections with its electronics.”

Hajimiri said that even with SSPD-1’s “goodbye and for so long” status, a number of invaluable milestones had been achieved. “The biggest challenge is raising awareness and making it clear that what we did is real.”

A scalable solution

three giant space cameras float above the Earth like a conical funnel, while purple rings shine down onto the planet below on the left.

The SPS-ALPHA space photovoltaics/space solar energy concept, as envisioned by John Mankins for the NASA Innovative Advanced Concepts (NIAC) program. (Photo: Mark Elwood / SpaceWorks Enterprises)

There is no clean, robust and exploitable energy technology other than space solar power (SBSP), says Troy, Michigan-based Virtus Solis Technologies Inc.

John Bucknell is the group’s CEO and founder. “Those of us who have compared all viable energy technologies know that a scalable solution must be low complexity, low mineral intensity, suitable for mass production and able to deliver reliable, safe and cheap electricity, as was the case most recently in the case of fossil fuels, 200 years,” he said.

Bucknell and colleagues are developing a design for an SBSP system that meets all of these criteria—a constellation of 16 arrays in space, each generating 20 gigawatts of power. A total of 320 gigawatts can be delivered anywhere in the world, he said, and the system can be scaled to increase its size.

“With a 50 percent year-over-year increase in efficiency, SBSP could reach 100 terawatts within 30 years and meet the needs of a planet of 10 billion people,” Bucknell said.

Disconnect

“There is still a disconnect between academic research and cost-of-production research in the aerospace industry and what private industry can achieve,” Bucknell said. “As a result, our $200 million forecast to complete research and development and launch a functioning pilot plant in orbit appears implausible.”

With Bucknell’s money, as well as investors’ money, it’s the energy industry that should hear and understand these options, he suggested, not the space industry.

“SBSP still sounds like science fiction because it doesn’t know that all the underlying technologies are already mature and all it needed was a commercial launch into space. Virtus Solis was the first to take advantage of this opportunity,” Bucknell said, “designed on a cost-target basis to address the global energy market.”

Investors want there to be no risk to revenue, Bucknell noted. “The orbital demonstration means you have a real product, so the remaining risks associated with on-orbit assembly and power transfer are demonstrated, and then the product can be scaled.”

Standing room only

The leader promoting the use of solar energy from space is John Mankins of Artemis Innovation Management Solutions in Santa Maria, California.

Mankins attended the April International Conference on Solar Energy from Space organized by European Space Agency (ESA) and the British Space Agency at the Royal Aeronautical Society in London.

“It was standing room only,” Mankins recalled. “Almost none of the 200 people played regularly and that was a huge change” – whether it was researchers in China working on space power technology or the European SOLARIS initiative. He added that work was underway in the UK, as well as progressive research into power transmission in Japan and other countries.

Ready for reuse

Mankins said the basis for energy transfer had been created many times through ground-based experiments. “For me, the power transfer function was demonstrated decades ago,” he said, “and now the real problem is how to make really large systems.”

For any type of space megaproject, “the most visible obstacle to space solar power seems ready to collapse,” Mankins advises, and that is cheap, reusable launchers.

Reusable rockets are leading the way SpaceX and its Falcon-class boosters, and now huge ones Spacecraft flight program. Similarly, Blue originThe New Glenn launcher is approaching its first flight. Other countries, such as ESA and China, are also pursuing reuse readiness in the amplifier industry.

Turn on the power

Nevertheless, there is something to work on in the coming years.

Pointing to the future, Mankins said systems-level demonstrations could solve problems such as finding the right design or determining how well technologies can scale and at what cost. It’s also important for spacecraft engineers to look at the rapid changes taking place in robotics here on Earth and apply that to space structures.

Moreover, the power sent from space must go beyond the range of nanowatts per square centimeter established by the Caltech experiment and reach into microwatts per square centimeter, Mankins advises.

“But in 2-3 years it will be a thousand times more powerful. There will be incredible progress,” Mankins predicts, “and then the cows will come out of the barn.”