Later this year, the US company Reflect Orbital plans to launch a test satellite called Eärendil-1 that will extend an 18-by-18-meter mirror in orbit. The goal is to test the feasibility of the company’s plans to launch up to 50,000 larger satellites, measuring 54 by 54 meters, and reflect sunlight to Earth on demand. The launch, which was approved by the Federal Communications Commission in July, has been met with disbelief by astronomers and environmental groups.
Assessing Light Pollution from Orbit
Astronomers have calculated the broader effect on the night sky. “There is no way you can do this and preserve dark skies,” states Miroslav Kocifaj, an astronomer at the Slovak Academy of Sciences. Reflect Orbital’s intention is to place its satellites into highly inclined orbits above Earth, almost from pole to pole. Eventually, the company has said, it wants to place satellites high enough to provide light 24-7 to locations on Earth.
Within the beam’s target area, intended to be a circular patch five kilometers across, a single Reflect Orbital satellite would appear about 40 times brighter than the full moon in the sky. As far as 14 kilometers away from the center of the beam, the satellite would still be as bright as the full moon.
The Compounding Effect of Satellite Constellations
Combining the beams of 400 satellites, which Reflect Orbital eventually plans to do, would yield a light as bright as 10,000 full moons within the five-kilometer area, or 2.4% as bright as the sun. Even up to 80 kilometers away, Kocifaj and his colleagues calculated, this combined beam would be visible as “a glow above the horizon".
Olivier Hainaut had previously modeled the broader effect of Reflect Orbital’s beams, finding they would brighten the sky up to 300% worldwide. Addressing Kocifaj's modeling, Hainaut noted, “They know what they’re doing”. Kocifaj similarly emphasizes, "Our calculations produce concrete figures".
Safety and Environmental Pushback
Due to these wide-ranging impacts, environmental organizations have formally challenged the project. In August, a group of organisations including DarkSky International and the American Bird Conservancy urged the FCC to review its approval of the Eärendil-1 satellite.
Jurisdictional and Regulatory Hurdles
Deploying these systems requires complex legal maneuvering. Reflect Orbital will need permission on a national and local level to reflect sunlight onto the ground. However, if the beams spread as much as Kocifaj and his team predict, “the company could need approvals in more than one jurisdiction,” says space lawyer Michelle Hanlon.