The idea of sending energy from space to an energy-hungry Earth has long been studied. It was first proposed in science fiction more than 80 years ago.
“It was quiet in the officer’s room of Solar Station No. 5 – except for the soft purring of the mighty Beam Director somewhere far below,” wrote the famous author Isaac Asimov in his April 1941 story “Reason,” which appeared in the magazine “Astounding Science Fiction.”
Asimov had his characters maintain a solar energy collection station in space that sent energy beams to receivers Soillike Mars. Fast forward to the 21st century, and studies here on Earth and now in space seem to reinforce the concept. Still, room Radiating solar energy is seen by some as a technology that is truly remote and outside the beam, an economically dubious concept that makes for good science fiction. Space.com reached out to several technologists to ask what’s new, what’s old, and what’s missing in the field of transferring energy to Earth from space.
Related: Scientists are beaming solar energy from space to Earth for the first time ever
Trio of technologies
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 demonstrator technology was launched into the orbital test space. Once in orbit, the SSPD-1 spacecraft tried out a trio of technological innovations designed to bring the solar energy needle in space closer to full reality. They were:
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DOLCE: A deployable ultralight composite experiment in space to demonstrate a new packaging scheme and implementation.
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ALBA: 32 different types of photovoltaic (PV) cells to assess how they can withstand the harsh space environment.
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MAPLE: A low-orbit power transfer microwave array based on custom integrated circuits with precise timing control to selectively concentrate power on two different receivers to demonstrate wireless remote power transfer in space.
Going to extremes
“A lot of things worked, and the things that worked well, we pushed them until they didn’t work anymore,” said Ali Hajimiri, co-director of the Caltech Space-Based Solar Power Project.
Hajimiri has focused on integrated circuits and their applications in various disciplines, such as biotechnology, communications and sensing, covering a wide range of frequencies from high-speed and radio frequency to low-frequency, high-precision circuits.
Yes, Hajimiri noted, there were problems during the nine-month SSPD-1 mission. “We literally had a problem on deployment, but the team resolved it. Even with the wireless power transfer, we had all kinds of situations. Then we really stressed the system towards the end of the mission – to the point where we were actively trying to damage to aim.”
Realization on the roof
On May 22, 2023, the SSPD-1 payout literally reached the roof of Caltech’s Gordon and Betty Moore Laboratory of Engineering. For just 90 seconds, the spacecraft’s MAPLE hardware beamed energy to Earth that was harvested in space.
Hajimiri is quick to explain that the energy level received at roof level was ultra-small. It was mostly about detection, he said, but the real buzz is taking into account the modest amount of energy received a small step for solar energy in space.
SSPD-1 will soon be dismantled and will take a destructive dive the Earth’s atmosphere.
The project’s attention is now focused on solving problems such as scaling up, enabling autonomous deployment and developing lighter structures.
Unknown unknowns
“There are many ‘unknown unknowns’ that have yet to be discovered,” Hajimiri said. In this phase of the work, the team is looking at manufacturing processes for fabric-like, low-cost arrays. Furthermore, timing synchronization is quite challenging, especially on a flexible, floppy structure floating through space.
“We’ve developed new ways to think about this problem,” Hajimiri added, “ways in which an array can determine its own shape and make corrections for it through its electronics.”
Even with SSPD-1’s “see you soon” status, a slew of invaluable milestones were achieved, Hajimiri said. “The biggest challenge is raising awareness and making it clear that what we have done is real.”
Scalable solution
There is no other clean, robust, dispatchable energy technology than Space-Based Solar Power (SBSP), according to Troy, Michigan-based Virtus Solis Technologies Inc.
John Bucknell is the CEO and founder of the group. “Those of us who have compared all viable energy technologies know that a scalable solution must have low complexity, low mineral intensity, mass production and be able to deliver robust, safe and cheap e-power, as fossil fuels have done so far have done.” 200 years,” he said.
Bucknell and colleagues are blueprinting an SBSP system that meets all these criteria: a constellation of 16 arrays in space, each pumping out 20 gigawatts of power. Collectively, 320 gigawatts could be delivered anywhere in the world, he said, a system that is scalable and can become much larger.
“With 50 percent annual capacity growth, SBSP could reach 100 terawatts of generation in 30 years and meet the needs of a planet of 10 billion people,” Bucknell said.
Detach
“There is still a gap between academic studies and research on the key manufacturing costs in aerospace and what private industry can achieve,” Bucknell said. “As a result, our $200 million forecast to complete research and development and get a functioning pilot plant into orbit seems incredible.”
For Bucknell’s money, and for investors’ sake, it is the energy industry that needs to hear and understand these options, he argued, not the space industry.
“SBSP still sounds like science fiction because they don’t know that the underlying technologies have all matured and just needed a commercial space launch to make this possible. Virtus Solis was the first to embrace this capability,” says Bucknell, “designed from a cost objective to address the global energy market.”
Investors want to see that there is no risk to earnings, Bucknell noted. “An orbital demonstration means you have a real product, so the remaining risk around space assembly and power transmission is demonstrated and then the product can scale up.”
Standing room only
A leader in advocating for harnessing solar energy from space is John Mankins of Artemis Innovation Management Solutions in Santa Maria, California.
Mankins in April participated in an international conference on solar energy from space, organized by the European Space Agency (ESA) and the UK Space Agency at the Royal Aeronautical Society in London.
“It was standing room only,” Mankins remembers. “Almost none of the 200 people were the regular players, and that was a huge change,” from researchers from China working on space-based power plant technology to Europe’s SOLARIS initiative. There is ongoing work in Britain, as well as progressive investigations into the spread of power in Japan and other countries, he said.
Reusable readiness
Mankins said the foundation for power beaming has been laid time and time again through experiments on the ground. “To me, power beaming as a feature was demonstrated decades ago,” he said, “and now the real issue is how to make really large systems.”
For any kind of megaproject in space, “the most visible hurdle to solar energy in space seems about to fall,” Mankins advised, and that is cheap, reusable launch vehicles.
Reusable rockets are a spearhead SpaceX and its Falcon class boosters and now the huge ones Starship flight program. In the same way, Blue origin‘s New Glenn launch vehicle is nearing its maiden flight. Other countries are also pursuing reusable readiness in the booster sector, such as ESA and China.
Boot up
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— This important test could bring solar energy in space one step closer to reality (video)
— Japanese satellite will send solar energy to Earth in 2025
Yet there is still work to be done in the coming years.
Pointing to the future, Mankins said system-level demonstrations could address issues such as finding the right design, or determining how well the technologies can scale and at what cost. It is also vital for aerospace engineers to research what is happening rapidly in robotics here on Earth and apply it to construction in space.
In addition, power emitted from space must move beyond Caltech’s nanowatts per square centimeter experiment to microwatts per square centimeter, Mankins advised.
“But in two to three years, a thousand times more power. There will be incredible progress,” Mankins predicts, “and then the cows will be out of the barn.”