The US Federal Communications Commission has authorized the launch of Eärendil-1, an experimental satellite equipped with a mirror that reflects sunlight toward Earth.
The project is led by the young California-based company Reflect Orbital. The authorization only covers a demonstrator, whose launch is planned for low Earth orbit. Its mirror is expected to measure 18 m per side. The company plans to concentrate a light spot about 5 km wide after sunset.
The announced goal is to provide light on demand, particularly for solar installations, construction sites, agricultural areas, or rescue operations. This light would therefore not come from onboard electrical power generation. The satellite would simply deflect the Sun's rays toward a region already in darkness.
In the long term, Reflect Orbital mentions a constellation of several tens of thousands of satellites. This scenario remains highly hypothetical and is not authorized by the current decision.
The concern is astronomical, literally: the American Astronomical Society denounces a risk for observations. The reflected brightness could damage certain sensitive instruments. The disruption of radio observations is also among its concerns.
Environmental groups, for their part, fear a new source of light pollution. Nighttime cycles influence many animals, plants, and human behaviors.
The demonstrator will make it possible to measure the real effects of this technology. Above all, it reignites a broader question: who should regulate the intentional illumination of Earth from space?