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Home News CPS Advocates for International Radio Astronomy Protection from Satellite Interference

CPS Advocates for International Radio Astronomy Protection from Satellite Interference

Nov. 20, 2023
The radio astronomy community takes a major step as proposals to add satellite constellation interference to the agenda of 2027 World Radiocommunication Conference are put forward.

The African Telecommunications Union (ATU) and the European Conference of Postal and Telecommunications Administrations (CEPT) have formally proposed new agenda items for the upcoming 2027 World Radiocommunication Conference (WRC-27). ATU and CEPT represent the telecommunication agencies in Africa and Europe. The proposals go back to major efforts of the IAU Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (CPS). Its members, in particular the European Science Foundation’s Committee on Radio Astronomy Frequencies (CRAF) [1], South African Radio Astronomy Observatory (SARAO) and CPS co-host SKA Observatory (SKAO) have been advocating for improved protection of radio astronomy from the negative effects of satellite constellations for years.

The WRC, organised by the International Telecommunication Union (ITU), is one of the highest authorities on radio communications, bringing together thousands of experts every three to four years to revise the Radio Regulations — an international treaty that defines the rules for the use of the radio spectrum. During this year’s four-week meeting starting 20 November, the agenda items for the 2027 conference will be decided.

“Securing an agenda item at the WRC is not an easy task and this would be the first radio astronomy agenda item for more than a decade. It is a long process and requires the support of many groups and nations. Radio astronomers are organised and united behind the need to act, owing to the rapid proliferation of large satellite constellations in the last couple of years, and we have seen growing momentum on this issue in recent months,” said Busang Sethole, Spectrum Engineer at the SARAO.

Under current plans, more than 50 000 satellites will be deployed in low Earth orbit by 2030, posing significant challenges for astronomers. Some major observatories are protected by radio quiet zones, which are geographical areas protected by national law. In these areas, large portions of the entire radio spectrum are managed to control all sorts of terrestrial radio transmitters. However, radio quiet zone laws do not apply to satellites, which can affect huge areas on Earth and can disturb observations in radio quiet zones even if they are operating in neighbouring airspace.

South Africa, which hosts the MeerKAT telescope, a precursor to what will be one of the major new telescopes of the SKA Observatory, has led the efforts within the ATU to further study this situation. The ATU’s proposed agenda item for the 2027 WRC addresses the international protection of radio quiet zones.

“For decades, the Radio Regulations have protected radio astronomy by reserving specific frequency ranges for its use,” said Waleed Madkour, CRAF’s frequency manager. “The rules have not kept pace with recent changes in low Earth orbit, with the launch of thousands of new satellites that are quickly filling the sky.”

A complementary initiative by radio astronomers in the Inter-American Telecommunication Commission (CITEL), proposing a mechanism to register radio quiet zones at the ITU Radiocommunication Sector (ITU-R), was presented to the Radiocommunication Assembly, which takes place before the WRC, with positive outcome.

“Satellite constellations can bring benefits for global connectivity, Earth observations, and navigation systems. However, they produce significant changes in the radio frequency environment, in our quiet skies. The CPS fully supports the initiatives to protect the radio sky at the ITU,” said Federico Di Vruno, co-director of the CPS and lead spectrum manager at the SKAO. The CPS is coordinating the global astronomy community’s efforts to study the impact of these satellites and to seek mitigation measures with administrations and industry.

The African and European proposals for 2027 agenda items reflect a coordinated effort by the radio astronomy community to have the issue addressed at the highest international level. Astronomers and many supporting countries are now seeking wider support for placing the proposals on the agenda for the next WRC. This complements the ongoing discussions at the UN Committee on the Peaceful Uses of Outer Space (COPUOS).


[1] The Committee on Radio Astronomy Frequencies (CRAF) is an expert committee of the European Science Foundation (ESF). CRAF is funded by major European radio astronomy observatories and research institutes, as well as SARAO, to preserve the quiet sky for radio astronomy and other basic sciences.

More information

NSF’s NOIRLab (National Optical-Infrared Astronomy Research Laboratory), the US center for ground-based optical-infrared astronomy, operates the International Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), Kitt Peak National Observatory (KPNO), Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and Vera C. Rubin Observatory (operated in cooperation with the Department of Energy’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona. The astronomical community is honored to have the opportunity to conduct astronomical research on Iolkam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence that these sites have to the Tohono O’odham Nation, to the Native Hawaiian community, and to the local communities in Chile, respectively.

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.

The International Astronomical Union’s Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (IAU CPS) is a global organisation co-hosted by the US-based NSF’s NOIRLab and the SKA Observatory (SKAO), under the auspices of the IAU. The CPS facilitates global coordination of efforts by the astronomical community in concert with observatories, space agencies, industry, regulators and other sectors to help mitigate the negative consequences of satellite constellations on astronomy.

The SKAO, formally known as the SKA Observatory, is an inter-governmental organisation composed of Member States from five continents. Its mission is to build and operate cutting-edge radio telescopes to transform our understanding of the Universe, and deliver benefits to society through global collaboration and innovation. Headquartered in the UK, its two telescope arrays will be constructed in Australia and South Africa and be the two most advanced radio telescope networks on Earth. Through the development of innovative technologies and its contribution to addressing societal challenges, the SKAO will play its part to address the United Nations’ Sustainable Development Goals and deliver significant benefits across its membership and beyond. The SKAO recognises and acknowledges the Indigenous peoples and cultures that have traditionally lived on the lands on which the SKAO facilities are located.



Busang Sethole
South African Radio Astronomy Observatory (SARAO)
Email: bsethole@ska.ac.za

Federico Di Vruno
SKA Observatory Spectrum Manager and co-Director of the IAU CPS
Email: Federico.DiVruno@skao.int

Mathieu Isidro
CPS Communications and Outreach Lead
Email: mathieu.isidro@skao.int

Benjamin Winkel
ESF Committee on Radio Astronomy Frequencies (CRAF)
Email: bwinkel@mpifr-bonn.mpg.de

Lars Lindberg Christensen
NSF's NOIRLab Head of Communications, Education & Engagement/IAU Director of Communications
Cell: +1 520 461 0433/+49 173 38 72 621
Email: lars.christensen@noirlab.edu


MeerKAT radio telescope
Credit: South African Radio Astronomy Observatory/'Sarel van Staden & Maryna Cotton See more


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