ESO and astronomy groups petition the UN to address the impact of satellites on dark and quiet skies

An international collaboration involving ESO has submitted a paper to the United Nations Committee on Peaceful Uses of Outer Space (COPUOS) proposing a new Expert Group to protect dark and quiet skies. The paper was discussed at the Scientific and Technical Subcommittee (STSC) of COPUOS under a dedicated agenda item on Dark and Quiet skies. The paper, which has been endorsed by Chile, Spain, Slovakia, Bulgaria, Dominican Republic, Peru, South Africa, in addition to ESO, the International Astronomical Union (IAU) and the Square Kilometer Array Observatory (SKAO), calls for a new Expert Group reporting to STSC that monitors the impact of satellites on astronomy, seeks inputs from global stakeholders and makes recommendations for mitigations.   

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.

Astronomers have already begun to notice the effects of the dramatic increases in space traffic. Even from remote locations — specifically chosen to isolate telescopes from unwanted light pollution — satellites interfere with optical and infrared observations. These satellites also transmit and receive radio signals, which is especially concerning for radio telescopes, such as the highly sensitive Atacama Large Millimeter/submillimeter Array of which ESO is a partner. 

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 (and 60% of Europeans) cannot see the Milky Way. These new satellites are encroaching on the few remaining dark sky reserves and radio quiet zones.

Andrew Williams, ESO’s External Relations Officer and representative of ESO at COPUOS, says “If we get to a stage where there are 100 000 or more satellites, irrespective of whatever mitigations the companies can do, they will have substantial impacts on astronomy. There’s also a danger of impacting our ability to discover potentially dangerous asteroids, as well as damaging the pristine sky that has been a constant of humanity.”

Some companies have made efforts to mitigate these effects with the use of less-reflective material in satellite construction or changing the orientation of satellites in space. Furthermore, companies can provide astronomers with higher accuracy information about the location of satellites so that observatories can take this into account to decide when and where to point their telescopes. While these potential solutions show promise, they will require a coordinated effort between satellite industry, governments, and astronomers. A cooperative approach involving all stakeholders is an effective way to reach a satisfactory balance between the need for the evolution of the low-Earth orbit space economy and the need protect the science of astronomy and the pristine visibility of the night sky.

The UN COPUOS, in which ESO is a permanent observer, facilitates discussion of matters relating to the use of outer space. A significant international effort, with contributions from ESO, has been made to continue the discussion of dark and quiet sky preservation at COPUOS, and in particular the impact of satellite constellations. 

ESO joined as signatory on a proposal submitted to the 60th session of STSC, along with other observer organisations International Astronomical Union and Square Kilometre Array Observatory, and COPUOS member States Chile, Spain, Slovakia, Bulgaria, Dominican Republic, Peru, and South Africa, which suggested the creation of a new Expert Group. The proposal was discussed extensively at the STSC and received wide ranging support from member states. 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 pristine night sky.

“There is a cascade effect from the discussions at COPUOS that can influence governments and companies to act. From the substantial number of countries from all regions of the globe that voiced support for our proposal, we are hopeful we can find a way forward at the main session of the committee,” says Andrew Williams, who is also co-lead of the policy hub of the IAU Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference. The mission of the Centre, which is also supported by ESO, is to coordinate efforts and unify voices across the global astronomical community with regard to the protection of the dark and quiet sky from satellite constellation interference. 

Courtesy of European Southern Observatory