The 46th COSPAR Scientific Assembly brought together experts from astronomy, the satellite industry, policy and law to examine one of the most important challenges arising from the rapid growth of activities in space: how to preserve dark and quiet skies while enabling satellite systems to continue delivering valuable services to society. The meeting was chaired by Marco Tavani.
By bringing together these different experts, the session provided an opportunity to consider the issue from scientific, technical, operational and regulatory perspectives. Panellists explored the progress already being made, the limitations of current approaches and the gaps to be addressed to ensure that the benefits of satellite technology can be realised without unnecessarily compromising astronomical observations or the wider value of the night sky.
In “Dark and Quiet Skies”, “dark” refers primarily to the effects of artificial light on optical astronomy, while “quiet” refers to interference affecting observations at radio frequencies. Together, optical and radio astronomy allow scientists to investigate some of humanity’s most fundamental questions like: How did the Universe develop into what we see today? What is our place within it? And could life exist elsewhere?
Satellites can affect both types of observation. In the optical domain, sunlight reflected from satellites and their components can leave bright trails across astronomical images or interfere with sensitive measurements. At radio frequencies, satellites may affect observations through their intended communication signals, unwanted emissions outside their assigned frequency bands, or unintended electromagnetic radiation generated by onboard electronic systems.
The session also recognised that these concerns form part of a broader discussion about the environmental and societal effects of activity in near-Earth space. Light pollution, possible atmospheric effects and the increasing risk of collisions in orbit are related challenges, although they were not the principal focus of the panel.
Some aspects of radio-frequency interference fall within the mandate of the International Telecommunication Union, which develops the international regulatory framework for the use of the radio-frequency spectrum. The session considered this work alongside the broader role of the United Nations Committee on the Peaceful Uses of Outer Space, or COPUOS, which addresses the peaceful uses of outer space and will continue to consider Dark and Quiet Skies under a dedicated agenda item over the next three years. The discussion highlighted the need for coordination between technical regulation and the wider consideration of how space activities can develop sustainably while preserving astronomy and the night sky.
Protecting dark and quiet skies is not solely a scientific concern. Naturally dark skies have cultural, educational and environmental value. Many species use natural patterns of light and darkness to navigate, reproduce or regulate their behaviour, while the night sky has inspired human curiosity, culture and scientific discovery throughout history.
This was the first time that Dark and Quiet Skies had been the subject of a dedicated discussion at a COSPAR Scientific Assembly. The strong interest in the session highlighted the role that COSPAR, with its broad international membership and multidisciplinary scientific expertise, can play in addressing this pressing issue and helping to develop solutions that balance the benefits of space activities with the protection of astronomy and the night sky. COSPAR will establish a dedicated Task Group on this topic to support the current initiatives.
We thank the esteemed speakers and panel for contributing to the wide-ranging and comprehensive discussion:
• Piero Benvenuti (CPS)
• Willy Benz (IAU President)
• Catherine Cesarsky (COSPAR Vice-President)
• Massimo Comparini (Leonardo)
• Federico Di Vruno (SKAO/CPS)
• Richard Anthony D’Souza (Vat. Observatory)
• Pascale Ehrenfreund (COSPAR President)
• Joseph Koller (Amazon Leo)
• Tanja L. Masson-Zwaan (Leiden University)
• Carole Mundell (ESA)
• Vadim Nozdrin (ITU)
• Roberto Ragazzoni (INAF President)
• Vijay Thakur (Eutelsat/Oneweb)
Media access
COSPAR 2026 is an in-person only event. Media accreditation for journalists, science communicators, freelancers and bloggers provides complimentary registration. All applications are subject to review based on the applicant’s professional media or communication output.
Opportunities for interviews with selected speakers, including space agency representatives, mission scientists and COSPAR leadership, may be arranged in advance and are subject to availability.
Useful links:
Scientific programme for 46th COSPAR Scientific Assembly
COSPAR website: https://cospar.world
Local Organising Committee www.cospar2026.org
Media contacts:
COSPAR 2026 Press Office: press.cospar2026@inaf.it
COSPAR Media contact: leigh.fergus@cosparhq.cnes.fr
About COSPAR
The Committee on Space Research (COSPAR) is an international scientific organization established in 1958, under the International Science Council (ISC). Its mission is to promote cooperation in space research, with an emphasis on the exchange of scientific results, information, and the development of global partnerships across disciplines for the benefit of all.
Through its scientific Commissions, Panels and Task Groups, COSPAR covers a wide range of space science fields, including Earth observation, planetary protection, astrophysics, and space life sciences and is a trusted advisor to the United Nations on critical issues in space research. It plays a key role in fostering collaboration between the global scientific community, space agencies, industry, and emerging space nations. Through specialized capacity building workshops, it supports the growth of space science expertise worldwide. Its biennial event, the COSPAR Scientific Assembly, brings together thousands of researchers from around the world, serving as a major platform for knowledge exchange and international dialogue.
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