Space mirrors could threaten astronomy and human eyesight
US company Reflect Orbital has won FCC approval to launch a test satellite, the first step toward a planned fleet of 50,000 space mirrors that would beam sunlight to Earth on demand. Astronomers warn of permanent eye damage risk and devastating harm to astronomical observation.
California-based Reflect Orbital is preparing to launch its test satellite, Eärendil-1, the first step in a plan for up to 50,000 orbiting mirrors designed to reflect sunlight onto chosen locations on Earth. The Federal Communications Commission has already approved launch of the 18-square-meter satellite. The company says the resulting light beam, potentially up to 5 kilometers wide, could power solar farms, boost agricultural yields, or aid nighttime search and rescue operations.
Concerns over eyesight and sky brightness
Astronomers warn the satellite will be as bright as Venus outside its beam and four times brighter than the Moon within it. Reflect Orbital itself acknowledged in its FCC filing that accidentally viewing the satellite through a 12-inch telescope — a common size among amateur astronomers — could cause permanent eye damage. The FCC dismissed these concerns as outside its regulatory authority, citing the value of testing innovative technology.
A threat to astronomy
Representatives of the American Astronomical Society and the Royal Astronomical Society warn that tens of thousands of mirror satellites could make night skies three to four times brighter due to atmospheric scattering, making it harder or even impossible to observe distant objects and asteroids from the ground. The company has not specified which observatories would be excluded from illumination and has no plan to warn the public about when and where the service will operate.
Lack of regulation
Independent researchers at Princeton have found the actual size of the light beam may be larger than the 24 square kilometers the company claims. Reflect Orbital says it is coordinating with the National Science Foundation, but the US currently has no federal regulation of satellite-caused light pollution, and the decision to dim or shut off the service would rest with the company itself.
