Reflections from the growing number of satellites orbiting Earth could spoil more than 95% of images taken by some upcoming space telescopes within the next decade, a NASA-led study published in Nature warns. The reflected sunlight appears as streaks, known as satellite trails, which have already been seen in images from the Hubble Space Telescope.
The study projects that missions such as NASA’s recently launched SPHEREx, the European Space Agency’s planned ARRAKIHS and China’s Xuntian Space Telescope could suffer severe contamination. Alejandro S. Borlaff, the study’s lead author and a NASA scientist, noted that a unique observation—“you are observing a galaxy and then suddenly a star far, far away explodes”—could be permanently lost if a satellite crosses the field of view.
Satellite launches have accelerated dramatically: more satellites were launched in the past four years than in the preceding 70 years of spaceflight, Borlaff said. As of Dec. 1, there were more than 10,000 active satellites in orbit, with SpaceX operating over 7,800 Starlink satellites. The International Telecommunication Union (ITU) says thousands more are planned.
Earlier research found that between 2018 and 2021 roughly 4% of Hubble images showed satellite streaks. The new study predicts a substantial rise—potentially at least one in three Hubble images showing a streak—and much higher contamination rates for certain new missions, with some instruments expected to have around 96% of images affected.
The issue extends to ground-based telescopes as well. The American Astronomical Society (AAS) has warned that large satellite constellations increase collision and debris risks and can cause glares and streaks that harm astronomical data. The ITU has called for stricter international regulations and better management of satellite networks to protect orbital sustainability.
Satellite operators say they are working to reduce brightness. SpaceX has tested darker coatings, added visors to block sunlight, and adjusted orbits to lower reflectivity. The AAS says it will continue collaborating with federal agencies and the satellite industry to understand and minimize impacts on astronomy.