Updated Feb. 24 to clarify scope of COPUOS work.
WASHINGTON — A United Nations committee will study the interference risks that satellite constellations pose to astronomy, a year after rejecting a similar proposal to do so.
At the conclusion of the meeting earlier this month of its scientific and technical subcommittee, the U.N.’s Committee on the Peaceful Uses of Outer Space (COPUOS) agreed to add an agenda item titled “Dark and quiet skies, astronomy and large constellations: addressing emerging issues and challenges” to its meetings in 2025 through 2029. That agenda will need to be approved by the full COPUOS in June.
The agenda item would allow COPUOS to address concerns about how satellite constellations can disrupt Earth-based astronomy. In this case, the focus will be on reflected sunlight from the satellites that can create streaks in optical and infrared images.
“This is a significant diplomatic moment for astronomy,” said Richard Green, an astronomer at the University of Arizona who serves as interim director of the International Astronomical Union’s Center for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference, or CPS, in a Feb. 15 statement. “Since the first constellation launches in 2019, we have been working hard to raise awareness of this issue with all relevant parties and at all levels. It’s very gratifying to see the United Nations recognize its importance and agree to look into the issues and challenges posed by large constellations.”
Adding the issue as an agenda item will allow more formal discussion about the topic at future COPUOS meetings. A long-term goal of the discussions is to develop recommendations on best practices to minimize satellite constellation interference that member states could potentially incorporate into national laws and regulations.
This was not the first time astronomers sought to include the issue of dark and quiet skies into the COPUOS agenda. COPUOS operates by consensus, requiring approval of all of its more than 100 member states to move forward on any issue, and thus allowing even a single nation to block action.
That was the case last year when astronomers sought to include a similar agenda item at COPUOS. “They work by unanimity, and so they have not yet persuaded every country in the world to take on this problem,” Green said during a session of an American Astronomical Society (AAS) meeting in January in New Orleans.
“COPUOS now has 103 member states and getting everybody to discuss these issues and agree on things is difficult,” said Ryan Guglietta of the U.S. State Department’s Office of Space Affairs during another session of the AAS conference. “If one country says no, then nothing happens on that specific issue.”
That was the case with the dark and quiet skies topic. “We did find an obstacle and a hurdle there in terms of getting this on the agenda,” he said of past COPUOS discussions.
In response, several nations established a more informal mechanism, called a “Group of Friends,” that was established by Chile and Spain and included 16 countries, such as the United States, along with several astronomical and space organizations. “It’s really kind of an advocacy group somewhat loosely under the auspices of the U.N. that meets and has these discussions,” he said, “with the goal of hopefully feeding this into the COPUOS process and establishing that agenda item.”
The COPUOS decision to study dark and quiet skies comes after another international organization, the International Telecommnuication Union (ITU), also agreed to study the topic. At the World Radiocommunication Conference (WRC) in Dubai that ended in December, ITU members agreed to add an agenda item for the next WRC in 2027 that will study radio quiet zones and protecting radio telescopes from interference caused by satellite constellations. That could potentially lead to new ITU regulations, binding on all nations, to mitigate such interference.
“The last time there was an agenda item on radio astronomy in the ITU was over a decade ago, so this really shows the significant profile and attention that astronomy has garnered in international bodies like the U.N.,” said Federico di Vruno, co-director of CPS and spectrum manager at the Square Kilometer Array Observatory, a radio telescope in Australia and South Africa, in a statement.
