Space mirrors threaten the night sky
Planned fleet of 50,000 sun-reflecting satellites raises concerns for astronomy and environment.
1Sunlight reflection from space
US company Reflect Orbital plans to launch the Eärendil-1 test satellite this year, carrying an 18x18 meter mirror. Their ultimate goal is deploying 50,000 larger satellites (54x54m) to reflect sunlight to Earth. The project aims to extend daylight hours for solar panel charging, emergency response, and military operations. The Federal Communications Commission (FCC) approved the project in July 2023, despite growing concerns from scientists.
2Astronomers' concerns
University of Regina astronomer Samantha Lawler states the project is "incompatible with astronomy." Slovak Academy of Sciences researcher Miroslav Kocifaj calculated light scattering effects. Their study in Astrophysical Journal Letters shows a single satellite would appear 40 times brighter than the full moon in target areas. Even 14km away, it would match the moon's brightness. European Southern Observatory's Olivier Hainaut confirms his earlier global brightness increase projections.
3Impact of 400 satellites
Reflect Orbital's plan to operate 400 satellites simultaneously would create light equivalent to 10,000 full moons (2.4% of sun's brightness) in target areas. Kocifaj's models show this glow would be visible up to 80km away as "a glow above the horizon." Hainaut's previous research suggested global sky brightness could increase by 300%. "These two papers really cover most of it," Hainaut commented about the combined research efforts.
4Company's counterarguments
CEO Ben Nowack disputes Kocifaj's findings: "Some assumptions are inaccurate." The company claims to have incorporated astronomers' feedback into their technology. However, Kocifaj notes Reflect Orbital hasn't provided supporting data: "No model descriptions, assumptions, or numbers - just claims." The company did warn the FCC that observing their satellite with large telescopes (common in astronomy) might be unsafe for human eyes.
5Regulatory challenges
University of Mississippi space lawyer Michelle Hanlon acknowledges potential benefits: "Could extend solar facility hours, provide disaster relief lighting." However, she notes the FCC only regulates communication frequencies, not reflector operations. If light scattering proves as significant as Kocifaj predicts, the company might need approvals from multiple jurisdictions. Currently, no global authority exists to regulate such space-based projects, leaving decisions to national bodies like the FCC.
6Environmental risks
In August 2023, a coalition including DarkSky International urged the FCC to reconsider its approval. They highlighted threats to astronomy, aviation, and wildlife. "Our request is simple: Reverse the decision and conduct proper environmental review," their statement read. The satellites could disrupt nocturnal animal behaviors and migrating birds' navigation. The American Bird Conservancy joined concerns about ecological impacts beyond astronomical observations.
7Polar orbit strategy
Reflect Orbital plans highly inclined orbits stretching pole-to-pole, enabling sunlight reflection during twilight hours. Their long-term vision includes satellites positioned to provide 24/7 illumination to Earth locations. While promising for energy applications, this could fundamentally alter global night environments. Astronomers emphasize that such projects require international oversight, as national regulators like the FCC lack comprehensive authority over space-based reflectors.
8A warning for the future
While pioneering space-based solar energy, uncontrolled deployment threatens astronomical research and ecosystems. Kocifaj warns: "These mirrors would seriously damage astronomy and nighttime environments far beyond target areas." Experts call for urgent international regulations, as current frameworks are inadequate. The Reflect Orbital case highlights growing tensions between space commercialization and preservation of Earth's natural night environment for science and ecology.
Original article: MIT Technology Review — Uzay aynaları gece gökyüzünü tehdit ediyor