Astronomers’ efforts to get the United Nations to back guidelines to stop satellites from spoiling telescopes’ views have become bogged down in diplomatic bureaucracy. At a U.N. subcommittee meeting earlier this month in Vienna, delegates did not unanimously back the formation of an expert group to draft guidelines that could establish norms to help protect the night sky. Astronomers hope the United Nations will eventually endorse such guidelines, but they now must wait to see whether backroom negotiations can put the issue on the agenda ahead of a meeting in June.

“An expert group is still on the table” but national delegations “will need to achieve a consensus view,” says Andrew Williams, external relations officer for the European Southern Observatory.

Astronomers have been pushing for ways to protect the night sky since May 2019, when rocket company SpaceX launched its first batch of Starlink satellites, in what is now a “megaconstellation” of some 3500 satellites that provides worldwide internet service direct from orbit. Stargazers were alarmed by how bright the strings of satellites appeared as sunlight reflected off their shiny surfaces. Although most telescopes can avoid the satellites’ bright trails, studies showed survey telescopes with wide fields of view, such as the upcoming Vera C. Rubin Observatory in Chile, would have trouble avoiding the disruptive streaks.

Radio astronomers were also concerned. The frequency band used by Starlink is adjacent to a band reserved for radio astronomy and any spillover could impact observations. Radio observatories are sited in remote locations, far from the interference of TV transmitters and cell towers, but that cannot protect them from transmitters orbiting overhead.

SpaceX has taken steps to reduce impacts by coating satellite surfaces with less reflective materials and changing their orientation. And last month, the U.S. National Science Foundation and SpaceX announced a formal agreement to continue to work on the issue, with SpaceX striving to reduce the brightness of its satellites to seventh magnitude or less—just below what’s visible to the naked eye. The company will also provide astronomers with orbital information so observatories can steer clear of the passing satellites as much as possible, and it will try to limit impacts on U.S. radio observatories. But until nations establish international norms, there’s no guarantee that the many other satellite companies planning megaconstellations will be as responsible. The first giant BlueWalker 3 satellite, for example, launched in September 2022, rivals the brightest stars in the sky.

Led by the International Astronomical Union (IAU), astronomers have been lobbying the Committee on the Peaceful Uses of Outer Space (COPUOS), a U.N. body with 102 national members. At this month’s annual meeting of COPUOS’s science and technical subcommittee, IAU proposed that the subcommittee set up an expert group—which could include academic and industry representatives—to study the issue for 3 years before presenting guidelines. IAU also wants the subcommittee to keep the issue as a permanent agenda item for that period.

The subcommittee has done similar things before: A decade ago it set up a working group on the sustainability of space activities that drafted guidelines to limit the creation of space debris. Those guidelines were eventually adopted by COPUOS, and variations of them have now been incorporated into national laws in more than 45 countries, including most of the major spacefaring nations. (China has yet to adopt them.)

The IAU proposal was well received. Williams says it was endorsed by more than 30 national delegations. Some cited the need for pristine skies for cultural reasons, whereas others supported the notion of dark skies tourism. The delegate of the United States, home to many satellite operators, appreciated that the expert group would involve industry. “There was a unique coming together,” says Theunis Kotzé, head of legal at the Square Kilometre Array Observatory.

But IAU didn’t have it all its own way. According to observers, Russia’s delegate supported the need to protect astronomy, but suggested there was no need for a new expert group, and said the issue could be dealt with by the existing working group on long-term sustainability of space activities. That’s something IAU and other backers oppose because it already has a full workload and its membership excludes scientific and industry experts. “We need solutions that are feasible and acceptable to those who operate the satellites,” IAU’s Piero Benvenuti says.

Some delegates also expressed concern about adding another new item to the subcommittee’s already crowded agenda. As delegates debated on the last day of the 2-week session how to streamline the agenda to fit in a new item, the IAU proposal was beaten by the clock. With those issues unresolved, the proposal does not automatically go forward for approval at the main COPUOS meeting in June. Instead, the core group of delegations that put it forward, including Chile, Spain, and South Africa—all hosts of major research telescopes—along with IAU and other backers, have 4 months to build consensus and refine the proposal to make it clear why the issue needs its own expert group. “Overall, the result is successful, with such a strong support from so many countries,” Benvenuti says.

Kotzé says he is optimistic that these “small differences of opinion” can be resolved by then. “The mere fact that dark and quiet skies was discussed at the U.N. is incredible,” he says.