Mega-constellation projects would have ‘devastating consequences for astronomy,’ warns the European Southern Observatory in a study, which estimates that the number of these devices should not exceed 100,000 in order to preserve our ability to observe the sky.
This study, led by the European Southern Observatory (ESO) and published Wednesday in Astronomy & Astrophysics, is the first to assess to what extent large and very bright satellite constellations, which also raise concerns about their health and environmental impact, would affect astronomical observations by making the night sky brighter.
Since 2019, the number of satellites in orbit around the Earth has risen rapidly, reaching about 14,000 today, mainly SpaceX’s Starlink telecommunications satellites.
And this is only the beginning. Elon Musk’s company plans to place another one million satellites into orbit, intended for space data centers.
Other projects, such as Cinnamon from startup E-Space or the Chinese constellations CTC-1 and CTC-2, would add hundreds of thousands of additional satellites into orbit.
Not to mention Reflect Orbital, an American startup that aims to launch by 2035 up to 50,000 very large mirror-like satellites to provide solar lighting at night using reflective beams.
In total, more than 1.7 million satellites could orbit around our planet and overwhelm the night sky that ground-based telescopes strive to observe.
To avoid dramatic consequences for ground astronomy, the number of satellites in orbit should be limited to 100,000 and those should be sufficiently faint to not be visible to the naked eye from a dark site, the study argues.
Light pollution generated by satellite constellations is not only a concern for astronomers. It can have repercussions on health and the environment, by disrupting the biological clocks of living beings and ecosystems. Large constellations also have direct impacts on air quality, during their launches and their re-entry into the atmosphere at the end of life.
