Space-Based Solar Power Gets Practical

The idea has always been, well, out there. What if we put giant arrays of solar panels in space, where the sun never sets and clouds never form, to collect limitless electricity to beam to Earth? For a world badly in need of clean, continuous energy, space-based solar power seems perfect, pure, ideal—until you begin to consider the cost, complexity and risk of assembling city-sized arrays high in Earth orbit.

Experiments have been conducted, plans made, and reports written over the last half century, and the consensus at the moment is that space-based solar is possible, but a lot still has to happen before it will be economical. “Indeed, the concepts detailed so far all seem to stand on shaky technical ground,” wrote Henri Barde, a veteran of the European Space Agency, in IEEE Spectrum in May.

But there may be more practical possibilities that are smaller and more limited in scope, and perhaps profitable with existing technology, space solar advocates say. Take, for example, a startup called Star Catcher, which announced plans in July to gather electricity with photovoltaic “power node” satellites in Earth orbit. These wouldn’t send a single watt from space to the ground. Instead, the node satellites would help power other satellites. The energy would be beamed to the satellites’ photovoltaic panels in the visible to near-infrared parts of the spectrum, augmenting the solar power they generate on their own.

“We’re going space-to-space,” says Andrew Rush, the CEO and a founder of the new company. “We don’t have to contend with the physics or the regulatory regime of going through the atmosphere. So that makes things a lot easier for us.”

Star Catcher energizes satellites

Executives at Star Catcher, based in Jacksonville, Fla., say there is a growing need for power forspacecraft. If, as is widely predicted, there are 50,000 satellites in orbit by 2030, they’ll need 840 megawatts of electricity a year (up from 40 megawatts today). Star Catcher’s power node satellites, each with a mass of perhaps 800 kg, would ride on commercial launchers and orbit at an altitude of about 1,500 km, serving clients’ satellites in low Earth orbit.

Star Catcher is starting small. So far the company reports it has raised US $12.25 million in seed funding and received letters of intent from half a dozen potential clients. If all goes well, it plans to launch a small demonstration satellite by the end of 2025. A single power node could serve multiple client satellites, Rush says. If there’s enough demand, he says he can someday imagine launching 200 power node satellites.

The International Space Station’s photovoltaic panels can generate 240 kilowatts in direct sunlight.NASA

Extra power from Star Catcher’s nodes could, for instance, supplement a satellite’s onboard power when it needs to run at peak levels. It could extend the life of a satellite whose own solar panels and batteries are losing efficiency with age. Or, if the business catches on, Rush says he can envision space companies building Star Catcher into their plans—spending less money (and launch mass) on large solar arrays and their electronics because they can routinely get extra energy from power nodes. That would let them concentrate on whatever their satellites’ actual missions are.

Operating in space is challenging, and Star Catcher says it won’t complicate things further. Companies needn’t add transponders, beacons or other extra systems to their satellites. They just tell Star Catcher a satellite’s orbital elements—its precise path in space—and the power node’s light beam will hit the satellite’s solar panels with 100 watts to 100 kilowatts of extra energy. That might increase available power by a few percent, or up to tenfold if needed.

“This is really meaningful,” says Rush, “because it lets us take these wonderful, smaller spacecraft that companies are deploying at just incredible rates in low Earth orbit, and give them big-satellite power.”

Sky-high potential and costs

Can this really work? People who have studied space-based solar say that on a technical level, the answer is probably yes. The bigger questions are economic. “I’m skeptical,” says Laura Forczyk, who runs a space consulting firm called Astralytical. For now, she says, there don’t appear to be many spacecraft, aloft or planned, that can’t take care of their own power needs. “So I think it’s really smart to start small and then see where the market grows.”

Vasilis Fthenakis, a senior research scientist at Columbia University and an IEEE Fellow, takes a different view. He has done extensive work on renewable energy, and says that today, the most promising applications of space-based solar are pretty much what Star Catcher is trying to do. He adds that there are remote places on Earth—think of Arctic installations or buoys at sea—that could benefit from orbital power beamed to Earth. He says he favors continued research on space-to-ground power transmission, but wouldn’t count on it as a global power source. “I don’t think it’s unrealistic. It’s not less realistic than nuclear fusion, right?” he says.

All this is obviously a comedown from the grand plans of past decades to solve all the planet’s energy problems. “It’s a very niche application as we’re discussing it right now,” says Anthony Peters, an electrical engineer and officer with the U.S. Space Force who is doing research on space-based solar under Fthenakis at Columbia. That said, he adds, “victory goes to the person who can get it to work first.”

Will auxiliary power be a priority in future years, or might Star Catcher find itself morphing to serve other needs? Maybe, says Forczyk. “Every company starts out wanting to change the world, and some of them make it.”