Telescopes in Space Under Threat from Satellite Megaconstellations

Currently, thousands of satellites orbit the Earth, frequently appearing as bright streaks that disrupt astronomical observations. While ground-based observatories like the Vera C. Rubin Observatory have long faced this challenge, the problem is now extending to space-based telescopes, including the iconic Hubble Space Telescope. The situation is expected to worsen as satellite deployments continue.

Projections indicate that by the late 2030s, Earth could host around 560,000 satellites, many organized into megaconstellationslarge groups of satellites working together to provide services like global broadband. According to a recent Nature study, even Hubble could capture a satellite in one out of every three images, while other telescopes may encounter satellite interference in nearly every exposure.

Alejandro Borlaff, an astrophysicist at NASAs Ames Research Center, emphasizes that although there is no exact threshold where satellite interference halts scientific research, the light pollution from these megaconstellations is already affecting data and distracting astronomers. If no solution is found, the situation will continue to deteriorate, Borlaff warns.

Researchers analyzed detailed plans for upcoming satellite launches, including satellite types and their orbits, to predict how they would impact space telescopes. They modeled effects on currently operating observatories, such as Hubble and NASAs SPHEREx (Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer), as well as upcoming telescopes like Chinas Xuntian and ESAs ARRAKIHS mission.

Each telescope faces different risks. Xuntian orbits at a relatively low altitude to allow astronaut servicing from Chinas Tiangong space station, exposing it to frequent satellite crossings. SPHEREx has low resolution, so each satellite affects a larger portion of its images and operates in infrared light, which satellites can still reflect. Overall, the analysis found that Xuntian and ARRAKIHS are most vulnerable, with dozens of streaks appearing in each exposure if 560,000 satellites are launched. In contrast, telescopes far from Earth, such as the James Webb and the upcoming Nancy Grace Roman Space Telescope, remain largely unaffected.

Even so, NASA notes that current satellite streaks on Hubble images are faint and manageable using standard data correction methods. For SPHEREx, repeated observations of the same targets reduce the chance that satellites will interfere with individual images. Nevertheless, astronomers have voiced concerns since the launch of SpaceXs Starlink constellation in 2019, especially regarding bright satellites seen from ground observatories.

Samantha Lawler, an astronomer at the University of Regina, highlights that astronomers across all fields are noticing gradually worsening observing conditions due to satellite streaks. While some have suggested relying entirely on space telescopes to avoid the issue, Lawler points out that this is neither cost-effective nor practical, and the study provides clear evidence of the growing challenge posed by satellite megaconstellations.

Author: Logan Reeves