The European Space Agency has joined an international effort to make satellites less disruptive to astronomy. A new agreement with the International Astronomical Union’s Centre for the Protection of the Dark and Quiet Sky links spacecraft engineering with the needs of observatories.
The agreement was signed in Antalya, Türkiye, on 7 October 2026. The IAU’s 9 October announcement identifies ESA as the first space agency to join the centre.
Two kinds of interference
Satellites can affect observations in different ways. Sunlight reflected from a spacecraft can leave a streak across an optical image. Electronics aboard it can also produce unwanted radio emissions, making it harder for radio telescopes to isolate faint signals from space.
ESA’s 8 October account emphasizes work before launch: darker surfaces, quieter electronics and models that predict how a spacecraft will appear to telescopes. ESA will bring technical expertise and connections with industry to that effort.
What the collaboration will work on
The IAU lists several practical areas: sharing methods for measuring satellite brightness and radio-frequency effects, developing more flexible operating modes, and improving coatings, materials and manufacturing. Standards and guidance for responsible spacecraft behaviour are also part of the planned cooperation.
Image processing can help with some contamination. In the Hubble example above, STScI explains that the trail can be identified and the scene recovered using other exposures of the same target. That illustrates one mitigation technique, rather than a universal answer to satellite interference.
The new memorandum establishes a programme of cooperation. Its value will depend on the technologies, operational changes and adopted practices that follow. For skywatchers and researchers alike, the important test is whether future spacecraft measurably reduce their impact on observations.
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