Proposed mega‑constellations threaten astronomical research
A recent study by the European Southern Observatory (ESO) has concluded that the current plans to deploy more than 1.7 million satellites into Earth orbit would dramatically impair the ability of modern telescopes to observe the night sky. The analysis highlights that the additional reflected sunlight from a large number of bright satellites would increase sky brightness and create frequent artefacts in astronomical images.
The report recommends limiting the total number of orbiting objects to no more than 100 000 satellites that remain invisible to the naked eye. Anything beyond that threshold would raise the likelihood of light contamination and collision‑generated debris, both of which pose significant challenges for precise observations.
Already, the proliferation of satellite constellations aimed at broadband communications and Earth monitoring is causing noticeable disruptions in optical and infrared data. Sensitive measurements, such as those required for deep‑field surveys, could become increasingly difficult as the sky grows brighter.
- Over 1.7 million satellites under consideration
- Suggested cap: 100 000 faint satellites
- Consequences: reduced image quality and higher debris risk
The authors call for coordinated international policies that address both the number of satellites and their reflectivity. Balancing the growing demand for satellite services with the preservation of a dark, clear night sky is essential for the future of astronomical science.