Mirrors! In Space!

Last week, I talked about the 100-plus-year fascination with space mirrors, including how its originator Hermann Oberth thought they’d be a good way to incinerate cities and/or control the weather. Fun times!

Fortunately, the “sun gun” application isn’t practical; the mirror array would have to be 62 miles in diameter, according to Oberth’s calculations. (The weather thing, however, would be easier to do.)

Other applications are still possible, and at least two startups are developing space mirror or space mirror-adjacent technology to beam sun power (hopefully safely) to the ground.

Their efforts open up possibilities, and, in some instances, concerns.

Reflect Orbital aims to launch satellites that will redirect visible sunlight to Earth, extending daylight hours past sunset and sunrise.

The satellites would be roughly 388 miles above Earth in a sun-synchronous orbit (which means they match the Earth’s rotation around the sun), and they’d largely be used to extend the hours solar farms generate electricity, though they could also beam visible light to support military operations, emergency response efforts, and give some literal flare to large entertainment events like Coachella.

The company is about to launch a test satellite named Earendil-1, which is following the startup trend of naming things after characters or objects from The Lord of the Rings. (In case you’re wondering and especially if you’re not, in LOTR the Star of Eärendil gives off light at dawn and dusk thanks to the half-Elven man of the same name who wears a Silmaril on his head as he sails through the sky. You’re welcome.)

It’s not clear when Earendil-1 will launch — The U.S. Federal Communications Commission (FCC) is currently reviewing their application, though you can keep tabs on Earendil-1 yourself by checking in on this orbital tracker.

Assuming it launches, Earendil-1 will unfurl a 60-foot-by-60-foot mylar sail to reflect the sun’s rays into a beam of light approximately three miles in diameter and as bright as a full moon. After Earendil, the company plans to have 1,000 satellites in the air by the end of 2028, 4,000 to 5,000 satellites by 2030, and 50,000 in the longer term, with larger mirrors beaming down light as bright as 100 full moons.

Many scientists and environmentalists are against Reflect Orbital’s plans. Extending light an hour or so beyond sunrise or sunset would impact the environment on Earth and make it harder for astronomers to study the night sky.

“Light pollution changes ecological relationships, not just individual organisms,” migration ecologist Andrew Farnsworth told me via email. He pointed to how artificial light disrupts bird migration patterns and animals’ circadian rhythms, which in turn affects “metabolism, reproduction, cell division, and predation, among other life history stages.” One 2025 study in the journal Global Change Biology also found that artificial light at night “represents a widespread and increasingly recognized global ecological threat.”

Because of these concerns, the Royal Astronomical Society, DarkSky International, and other organizations have spoken out against the Earendil-1 launch and submitted objections to the FCC. Whether the FCC decides those comments are enough to nix the launch, however, remains to be seen.

Space mirrors come with concerns, but another technology developed by the startup Overview Energy aims to harness space solar energy in a different way.

Overview, like Reflect Orbital, envisions a series of satellites beaming down space solar energy. In Overview’s case, however, the satellites will send near-infrared light — light just outside of what humans can see and feel — rather than visible light.

To do so, Overview’s system uses reflectors to concentrate sunlight onto on-board solar panels (see #1 and #2 below respectively). The solar panels generate electricity, which powers near-infrared laser diodes (#3) lining the two “fans” of the satellite. The diodes are kept from overheating by radiators that siphon off excess heat (#4), and then all those near-infrared diodes feed into fiber optic cables. Those cables bring all the light into a centralized optics system (#5), which then combines the light into a wide, near-infrared beam aimed at the ground.

Overview’s satellites would be in geosynchronous orbit 22,000 miles above Earth, which means they would match the planet’s rotation, causing their beams to be above the same spot on the planet at the same time each day. The goal is to have the satellites power solar farms, and they’ve found that PV panels convert about 50% of their near-infrared beam into electricity, which is roughly double a PV’s conversion rate of direct sunlight.

Each satellite will provide 1Megawatt (MW) of electrical power once converted, and each beam will be a few kilometers wide. The end goal is to have hundreds of satellites working together, and Overview has already signed a deal with Meta to provide up to 1 Gigawatt (aka 1,000 MW) of power for the corporation’s data centers and entered contract with the U.S. Air Force to power remote and/or key bases.

Overview plans to test its technology in low-Earth orbit in January 2028, and CEO Marc Berte told TechCrunch that the company plans to have 1,000 satellites in the sky generating that 1 GW of power by 2030. To put things into context, that’s roughly the amount of energy need to power 876,000 U.S. homes in a year. To put it in another context, the average energy power needed in the U.S. in 2025 was 457 GW.

There are environmental and sky-related concerns here as well: adding a thousand more satellites above us will impact astronomy efforts, though near infrared, according to Farnsworth, “should probably be treated as lower-risk than blue-rich or broad-spectrum white light.” That doesn’t mean, he cautioned, that it’s risk-free. Plants and some insects and bugs are more sensitive to near infrared, for example, and there’s much we don’t know, as artificial light at night studies have primarily focused on visible light.

Whatever happens, this is the closest we’ve come to having commercial space mirrors in orbit since Oberth first thought of the idea over 100 years ago. Will Reflect Orbital or Overview Energy be the first to provide space solar power? Do we even need space solar power? The next few years will tell us much.