Space mirrors for solar power may threaten astronomy, experts warn

Reflect Orbital, a California-based startup, proposes deploying a large constellation of satellites equipped with Mylar mirrors to reflect sunlight down to Earth, enabling solar farms to generate power even after sunset. The company plans to launch a test satellite, Earendil-1, in 2026, followed by up to 4,000 satellites by 2030, with potential expansion to 250,000 satellites featuring 54-meter mirrors. These satellites would orbit about 625 km above Earth and reflect light approximately 15,000 times dimmer than midday sun but still brighter than a full moon, aiming to provide “sunlight on demand” to targeted locations. However, astronomers and environmentalists warn that this project could severely impact astronomy and ecosystems. Unlike existing satellites that cause unintended light pollution, Reflect Orbital’s mirrors are designed to reflect light deliberately, potentially creating “blindingly bright” flashes that could damage sensitive astronomical instruments and even pose risks of eye damage to observers. The brightness could drown