Space Mirrors Could Obscure Night Sky, Study Warns

Reflect Orbital's ambitious plan to deploy a constellation of space mirrors designed to beam sunlight to Earth on demand faces significant criticism from astronomers, who warn of detrimental impacts on the night sky. The US-based company intends to launch a test satellite, Eärendil-1, later this year. This initial satellite will feature an 18-by-18-meter mirror designed to test the feasibility of its larger-scale vision: deploying up to 50,000 satellites, each equipped with a 54-by-54-meter mirror. The stated purpose for this technology is to extend daylight hours for various applications, including charging solar panels, facilitating emergency response operations, and supporting military activities. The Federal Communications Commission (FCC) approved the launch in July, a decision that has drawn sharp disapproval from both the astronomical community and environmental advocacy groups.

Astronomers express deep concern over the potential light pollution generated by these orbiting mirrors. Samantha Lawler, an astronomer at the University of Regina in Canada, stated that the project is "incompatible with astronomy" and that preserving dark skies would be impossible. Further analysis by Miroslav Kocifaj, an astronomer at the Slovak Academy of Sciences, and his colleagues, detailed in a paper accepted for publication in Astrophysical Journal Letters, quantifies the potential scattering of light. Their calculations indicate that within the intended five-kilometer diameter target area for a single satellite's beam, the satellite would appear approximately 40 times brighter than the full moon. Even at distances up to 14 kilometers from the beam's center, the satellite would still be as luminous as the full moon. This suggests a substantial increase in artificial light at night, potentially disrupting astronomical observations and nocturnal ecosystems.

The cumulative effect of Reflect Orbital's full constellation of 400 satellites has been projected to be even more dramatic. Kocifaj's research indicates that the combined beams would create a light within the five-kilometer target zone as bright as 10,000 full moons, or 2.4% of the sun's brightness. The study further calculated that even at distances as far as 80 kilometers from the beam's center, the combined light would still be significantly brighter than current ambient night sky conditions. This level of illumination raises concerns not only for professional and amateur astronomers but also for wildlife that relies on natural darkness for navigation, foraging, and reproduction. The potential for widespread light pollution extending far beyond the intended operational zones highlights the significant environmental and scientific challenges posed by Reflect Orbital's proposed space-based solar augmentation system.