A risky plan to turn night into day is one step closer to reality. Last week, U.S. officials approved a mission to launch a giant mirror into space, where the device will reflect sunlight onto shadowed parts of Earth. The startup behind the mission aims to place 50,000 mirrors into orbit by 2035, enabling “full noon” brightness at select points.

The new company, Reflect Orbital in Hawthorne, California, says it intends to make “clean, abundant energy available on demand.” The company says its “daytime” production bags could increase agricultural productivity, aid in natural disaster relief efforts and allow solar panels to produce electricity at night.

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But many astronomers are concerned that rays from orbiting mirrors will interfere with sensitive telescope equipment and increase light pollution. “With 50,000 satellites, that would probably mean the end of terrestrial astronomy, or at least optical astronomy,” says Roohi Dalal, deputy director of public policy at the American Astronomical Society in Washington, DC.

A company spokesperson says this claim “demonstrates a lack of understanding of our technology” and that Reflect Orbital has guardrails to ensure its technology does not interfere with astronomers’ work. The company has had conversations with scientists and will continue to do so, the spokesperson says. “Feedback from the astronomical community has already materially informed our spacecraft design and operational plans.”

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How does the technology work and what is the goal of the test mission?

After receiving approval from the US Federal Communications Commission on July 9, Reflect Orbital plans to launch its first satellite, Eärendil-1, later this year, into an orbit 625 kilometers above the Earth’s surface. From there, the mini-fridge-sized spacecraft will deploy a mirror the size of a tennis court, but 28 times thinner than a human hair. The mirror will be oriented toward direct sunlight at multiple test locations, and the Reflect Orbital team will evaluate the deployment and orientation mechanisms. The first mirror will illuminate an area of ​​approximately 24 square kilometers on the Earth’s surface. The light can be turned off on request.

“This first satellite will be a testing ground and we will really have the opportunity to show how we can create good in the world without lighting where people don’t want it,” says Reflect Orbital co-founder and CEO Ben Nowack. His team has created hundreds of mirror prototypes, he says. The company plans to launch more test missions and is asking independent researchers to study the effects of its devices.

What are the challenges facing this technology?

The entire mission is “incredibly risky and we are accepting that risk. We are ready to face it firsthand,” Nowack says.

As with any satellite, a small error in a piece of hardware or software could lead to a faulty mirror implementation. “It’s the simple things that get you,” says Darren McKnight, senior technical fellow at LeoLabs, a spacecraft and debris tracking company based in Menlo Park, California.

And once the mirror is deployed, Reflect Orbital will need to carefully monitor the effects of debris from other spacecraft orbiting Earth, McKnight says. Pieces of artificial debris of millimeter and centimeter sizes are common at the altitude where the satellite will orbit and could collide with it; Repeated impacts on the ultra-sensitive mirror may reduce its effectiveness. Additionally, this altitude has a high concentration of atomic oxygen, a highly reactive substance that erodes spacecraft surfaces and could damage the mirror.

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