Plans to launch more than 1.7 million new satellites into Earth orbit could severely impact astronomy, warns the European Southern Observatory (ESO). According to a study published in the journal Astronomy & Astrophysics, scientists estimate that to preserve the ability of modern telescopes to effectively observe the night sky, the total number of satellites in orbit should not exceed 100,000—and they must be faint enough to remain invisible to the naked eye.
Since 2019, the number of active satellites has surged dramatically, reaching approximately 14,000 today. Including inactive satellites and space debris, the total exceeds 32,000 objects—most of them belonging to SpaceX’s Starlink communications constellation.
Although companies like SpaceX have taken steps to reduce satellite brightness, researchers stress that the scale of planned deployments now surpasses what astronomical research can sustain. As Olivier Hainaut, lead author of the study and ESO astronomer, explains, these proposed mega-constellations threaten to permanently alter humanity’s view of the night sky.
SpaceX plans to launch up to one million additional satellites—not only for broadband but also to build orbital data centers. Other initiatives, including E-Space’s Cinnamon constellation and China’s CTC-1 and CTC-2 programs, aim to add hundreds of thousands more satellites. Particularly concerning is U.S.-based startup Reflect Orbital, which intends to deploy satellites equipped with massive reflective mirrors designed to bounce sunlight down to Earth at night—effectively creating artificial illumination.
The company aims to launch its first such satellite within the year and build a fleet of 50,000 by 2035. According to the study, these satellites would be the brightest ever placed in orbit, drastically altering the natural darkness of the night sky. In light-polluted cities like Munich, they could become the only visible bright objects overhead.
Researchers warn that widespread deployment of such constellations will significantly hinder observations of distant galaxies, exoplanets, and near-Earth asteroids—some of which pose potential threats to our planet. They conclude that these harmful effects can be avoided only if the total number of existing and future satellites is capped at around 100,000 and their brightness remains below the threshold of naked-eye visibility.
Both SpaceX and Reflect Orbital have already filed applications with the U.S. Federal Communications Commission (FCC) for regulatory approval.