ESA signs agreement with International Astronomical Union on keeping the sky dark and quiet

The European Space Agency (ESA) and the International Astronomical Union’s Centre for the Protection of the Dark and Quiet Sky (IAU CPS) have signed an agreement at the International Astronautical Congress to strengthen cooperation and develop technical solutions aimed at reducing the impact of satellites on astronomy.

The agreement comes as the number of satellites in orbit continues to rise, increasing concerns about reflected light and radio frequency interference affecting professional astronomy as well as amateur stargazing.

ESA said the Memorandum of Intent is intended to combine ESA’s technical expertise with the IAU CPS’s network of astronomical institutions, observatories, researchers, companies and citizens focused on raising awareness of satellite interference.

Under the arrangement, ESA said it will work with industry to develop practical measures that reduce the impact of satellites on astronomical observations, including design-stage choices intended to limit unwanted reflections and radio emissions.

“This collaboration marks an important step towards a future where valuable astronomical observations and other space activities can coexist, allowing scientists to continue exploring the cosmos while future generations can still enjoy an unobstructed view of the stars,” says Rolf Densing, Director of Operations at ESA.

ESA also pointed to growing operational and scientific concerns linked to the rapid expansion of low-Earth orbit satellite constellations. Jan Siminski, a space debris analyst at ESA, said satellite reflections can create bright streaks across telescope images and that electronic systems onboard spacecraft can produce unintended radio emissions that interfere with sensitive radio telescopes.

“Astronomers rely on uninterrupted observations to study the origins of the Universe, search for potentially habitable worlds and track near-Earth asteroids that could pose a hazard to our planet. It is crucial that we find ways to prevent interference.”

Beyond astronomy, the release noted that many animal species depend on natural night-time conditions for navigation, framing dark-sky protection as an environmental consideration as well as a scientific one.