Rapidly growing satellite constellations have raised strong concerns among the scientific community1–4. Reflections from satellites can be visible to the unaided eye and extremely bright for professional telescopes. These trails already affect astronomical images across the complete electromagnetic spectrum, with a noticeable cost for operations and mitigation efforts. Contrary to popular perception, satellite trails affect not only ground-based observatories but also space observatories such as the Hubble Space Telescope5. However, the current number of satellites is only a fraction (less than 3%) of those to be launched in the next decade. Here we show a forecast of the satellite trail contamination levels for a series of international low-Earth-orbit telescopes on the basis of the proposed telecommunication industry constellations. Our results show that if these constellations are completed, one-third of the images of the Hubble Space Telescope will be contaminated, while the SPHEREx (Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer), ARRAKIHS (Analysis of Resolved Remnants of Accreted galaxies as a Key Instrument for Halo Surveys) and Xuntian space telescopes will have more than 96% of their exposures affected, with $${5.6}_{-0.3}^{+0.3}$$ , $${69}_{-22}^{+21}$$ and $${92}_{-10}^{+11}$$ trails per exposure, respectively, with an average surface brightness of μ = 19 ± 2 mag arcsec−2. Our results demonstrate that light contamination is a growing threat for space telescope operations. We propose a series of actions to minimize the impact of satellite constellations, allowing researchers to predict, model and correct unwanted satellite light pollution from science observations. Rapidly growing satellite constellations pose a substantial threat to astronomical observations, with projections indicating that future space telescopes will have more than 96% of their exposures affected by satellite trails, necessitating urgent mitigation strategies.