The proliferation of satellites launched into orbit around the Earth has improved our ability to communicate globally instantaneously; however, there are concerns about the impact these technologies have on astronomical observations and the preservation of dark and quiet skies. At the time of writing there are over 8000 active and defunct satellites orbiting the Earth and this number will continue to grow. As many as 100 000 satellites could be launched in the coming decade.

The rapid growth in light pollution, which is only being exacerbated by the new satellites, impacts us all. Many of us have never seen an unobscured night sky and over a third of humanity cannot see the Milky Way. These new satellites are encroaching on the few remaining dark sky reserves and radio-quiet zones.

From 6 to 17 February, a delegation from the International Astronomical Union (IAU) attended the 60th Session of the Scientific and Technical Subcommittee (STSC) of the UN Committee on the Peaceful Uses of Outer Space (COPUOS) in Vienna, Austria. One of the most debated issues at the meeting was the protection of the dark and quiet sky from interference by large constellations of satellites. In particular, the work of the new IAU Center for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (CPS, a partnership between the IAU, the NSF’s NOIRLab and the SKAO) galvanised discussion.

A major topic of discussion during the meeting was the Conference Room Paper on the Protection of Dark and Quiet Skies for Science and Society, which was presented by the delegations of the IAU, Chile, Spain, Slovakia, Bulgaria, Dominican Republic, Peru, South Africa, ESO and the SKAO. The paper describes the achievements of the IAU CPS during its first year of activity. It confirms that a cooperative approach involving all stakeholders is an effective way to reach a satisfactory balance between the evolution of space technology and the need to protect the science of astronomy and the pristine visibility of the night sky.

Although this progress is encouraging and should be continued, the paper recognises that the issue is far from being resolved. In fact the situation regarding satellites in low Earth orbit is rapidly evolving, with new companies and agencies continuing to plan their constellations and proposing new types of satellites of varying sizes and characteristics. For this reason, the paper stresses that it is essential that the STSC continues to be kept well informed on the matter, so it will be in a position to evaluate the effectiveness of the suggested voluntary mitigating measures.

The paper made two proposals for further action. Firstly, it recommended that dark and quiet sky protection be kept on the agenda of the next three sessions of the STSC. Secondly, the paper proposed the creation of an Expert Group with the task of promoting awareness of and providing guidance on the impact of satellite constellations on astronomy, as well as enabling communication and cooperation between Member States and stakeholders. Both proposals obtained the support of more than 30 delegations. Several delegations also explicitly praised the work of the CPS and its cooperative approach to the issue.

In order to refine the details and gain more support amongst COPUOS members, the team, under the lead of Chile as first co-signatory of the paper, will continue to work towards advocating for the inclusion of the matter under COPUOS at its main session in June 2023. It is hoped that discussions during the period between the sessions will produce solutions that could be even more effective in protecting the science of astronomy and the visibility of the night sky.

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The IAU is the international astronomical organisation that brings together more than 12 000 active professional astronomers from more than 100 countries worldwide. Its mission is to promote and safeguard astronomy in all its aspects, including research, communication, education and development, through international cooperation. The IAU also serves as the internationally recognised authority for assigning designations to celestial bodies and the surface features on them. Founded in 1919, the IAU is the world's largest professional body for astronomers.

Contacts

Lars Lindberg Christensen
IAU Director of Communications
Cell: +1 520 461 0433/+49 173 38 72 621
Email: lars.christensen@noirlab.edu