At the end of June, more than 250 astronomers, engineers, satellite operators, and other stakeholders attended SATCON1. This was a virtual meeting to discuss the mega-constellations of low-Earth orbit satellites (LEOsats) and how they will affect the night sky.

A report now details the issues of these mega-constellations, while also suggesting solutions to minimize their impact on astronomical observations, amateur astrophotography, and the general enjoyment of the night sky.

“If the 100,000 or more LEOsats proposed by many companies and many governments are deployed, no combination of mitigations can fully avoid the impacts of the satellite trails on the science programs of current and planned ground-based optical-NIR astronomy facilities,” the report states. “Astronomers are just beginning to understand the full range of impacts on the discipline. Astrophotography, amateur astronomy, and the human experience of the stars and the Milky Way are already affected.”

The urgency of this meeting is due to the launch of over 650 satellites by Elon Musk’s SpaceX since May 2019. The Starlink constellation, as it is called, has affected astronomical observations from the get-go, concerning many scientists about what the full constellation and other proposed LEOsats would do to the sky.

The report proposes several options to tackle the issue. The obvious choice is to stop the harm to ground-based astronomy by not launching the mega-constellations. If politicians are not willing to curb or regulate the launches, then it is paramount that these satellites impact observations as little as possible. This means they should be at low altitude (less than 600 kilometers/370 miles), darkened, and rotated to reflect as little sunlight as possible.

Even under these conditions, they will still affect twilight observations key for the discovery of dangerous asteroids, as well as the search for outer solar system objects and the visible-light counterpart of gravitational wave sources.

The SATCON1 team also put forward recommendations for observatories, such as the Vera Rubin and the upcoming Extremely Large Telescope, to help them find ways to eliminate satellite trails or look at other regions of the sky. This requires knowing precisely where the satellites are going to be and how they will move.

These fixes are both work-intensive and expensive and have many people demanding that the mitigating approaches be paid by the private companies putting these satellites up. They created the problem, it shouldn’t be up to publicly funded observatories to solve it, they say.

“Our team at the AAS was enthusiastic to partner with NOIRLab and bring representatives of the astronomical and satellite communities together for a very fruitful exchange of ideas,” AAS President Paula Szkody, from the University of Washington, said in a statement. “Even though we’re still at an early stage of understanding and addressing the threats posed to astronomy by large satellite constellations, we have made good progress and have plenty of reasons to hope for a positive outcome.”

A second workshop, SATCON2, that tackles issues of policy and regulation is expected to happen in the first six months of 2021.