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Astronomers propose 'SatHub' to address growing threat of satellite megaconstellations

The image shows diagonal lines caused by the light reflected by a group of 25 Starlink satellites passing through the field of view of a telescope at Lowell Observatory in Arizona during observations of the NGC 5353/4 galaxy group on May 25, 2019.
The image shows diagonal lines caused by the light reflected by a group of 25 Starlink satellites passing through the field of view of a telescope at Lowell Observatory in Arizona during observations of the NGC 5353/4 galaxy group on May 25, 2019. (Image credit: Victoria Girgis/Lowell Observatory)

Some astronomers suggest setting up a "SatHub" to address the growing threat that satellite megaconstellations pose to the night sky — but funding and support are necessary to make it happen.

The primary goal of the international SatHub project would be implementing and adapting plans for observations as new satellites go up, team members said. A secondary goal would be training, outreach and analysis concerning low Earth orbit satellites for the greater community.

SatHub was one of the key recommendations emerging from a recent workshop, called Satellite Constellations 2 (SATCON2), to figure out how astronomers can best perform observations in the face of swiftly growing satellite numbers. (Some satellite companies also participated in workshop discussions.)

Related: Astronomers ask UN committee to protect night skies from megaconstellations

"That may include a proposal to the International Astronomical Union," SATCON2 co-chair Connie Walker said during a preliminary press conference on July 16, referring to the SatHub idea. The IAU is one of the largest organizations representing astronomers and astronomy interests around the world. 

"They have a call that just went out recently on such a center, so stay tuned for more on that," added Walker, a scientist at the National Science Foundation's NOIRLab.

Proposals are due to the IAU on Sept. 10, and deliberations will likely continue until at least the end of 2021, representatives added in the workshop. They did not give a timeline for when SatHub could be available, but this would likely depend in large part on funding.

Ideally, companies that send satellites to space should put money toward the center, said Meredith Rawls, a research scientist at the University of Washington who was also the observations working group chair for SATCON2.

"The idea here is to have a one-stop shop for all of your different needs pertaining to low Earth orbit satellite constellation observations," Rawls said during the press conference. "We really would like to get out ahead of this and avoid reinventing the wheel by having lots of individual siloed groups addressing the problem, and instead have a single landing place for all of these different observations and related analyses to land."

SATCON2 had three objectives, according to a press release from NOIRLab and the American Astronomical Society (AAS), which jointly organized the workshop: to figure out what is required to implement the previous recommendations from 2020's SATCON1; to have astronomers and satellite operators work together for policy frameworks and strategies; and to increase the diversity of all stakeholders.

SATCON1 participants produced a report last year warning that the impacts on astronomy of satellite megaconstellations in low Earth orbit "are estimated to range from negligible to extreme." All-sky survey telescopes that depend on lengthy light exposures free from interference will feel the biggest effects, the report concluded.

Report: Satellite megaconstellations could have 'extreme' impact on astronomy

Key recommendations from 2020 included limiting satellite altitudes in low Earth orbit to 370 miles (600 kilometers); reducing satellite brightness; developing image-processing software to minimize satellite trails; and making orbital information about satellites widely available so astronomers can point away from them.

This year, SATCON2 astronomers pointed to challenges in keeping up with the growing pace of satellite launches. Among the conclusions was that substantial development will be needed in software solutions, said Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics who was co-chair of the SATCON2 algorithms working group.

"We've tried to identify what existing software is relevant to the software problems, but we find that a lot of it is specialized to particular instruments or particular observatories, and it's going to need some work to be generalized," he warned during the press conference. "Also, there are big gaps where the software just doesn't exist. We do need a significant software development effort, and that's going to require substantial resources and funding."

Since satellites are always launching and software takes time to be developed, "we're going to need these resources as soon as possible," McDowell added. And the money will not only be needed for software, he added: Spectroscopic observations in particular are likely to be highly affected, so some observatories will likely need to spend money on hardware such as auxiliary spotting cameras.

The problem also goes beyond technical issues. Other commonly cited problems of constellations include space junk and crowding in terms of radio interference between satellites. These issues were not addressed in the workshop, but there were discussions concerning the impact on Indigenous peoples, as lack of access to the sky is seen as a cultural loss, said James Lowenthal, an astronomy professor at Smith College at Northampton, Massachusetts, who was the co-chair of the SATCON2 community engagement working group. (That said, he warned, not all Indigenous groups want the same thing.)

"The sky belongs to everyone," Lowenthal said. "People are impacted by changes in the sky. Megaconstellations are a global issue because space is a global commons. The sky is part of the environment … and ecosystems depend on the night sky, and on each other, echoing the intersectional, interdependent nature of the many strands of this complex issue."

Lowenthal suggested that, when coming with policy solutions, stakeholders should look to lessons learned from past global commons agreements such as the 1987 Montreal Protocol on Substances That Deplete the Ozone Layer, which led to some restrictions on CFCs. But not all such agreements were that successful, he said.

"Telephones, trains, planes, cars, fossil fuels, the internet itself — all of these technologies burst upon the scene, were disruptive, produced profound change in society, to be followed by some modicum of regulation and lawmaking. Some were more successful than others at protecting public interests," Lowenthal said.

One way of mitigating the megaconstellation issue might be for those involved in satellite constellations to anticipate impacts long before satellites launch, said Richard Green of the University of Arizona's Steward Observatory, director of the Large Binocular Telescope Observatory and chair of the SATCON2 policy working group.

Related: Air pollution from reentering megaconstellation satellites could cause ozone hole 2.0

A fleet of SpaceX Starlink internet satellites is seen poised for deployment in orbit in this image from a May 24, 2019 launch.

A fleet of SpaceX Starlink internet satellites is seen poised for deployment in orbit in this image from a May 24, 2019 launch. (Image credit: SpaceX)

The policy working group "wanted to encourage operators to consider effects on astronomy, early in their development of their constellations," Green said. Acknowledging that SpaceX creates satellites in-house, most other companies contract for construction, he added. "They can adjust designs early, but it's very hard to change once they're in production."

Among other measures, the policy working group urged individual countries — who are responsible for their launching entities, under the United Nations' 1967 Outer Space Treaty recognized in international space law frameworks — to grant licenses to satellite operators only after the environmental impact of satellites has been assessed and minimized.

Despite the Outer Space Treaty's age, Green noted, it remains a useful tool for policy discussions. "It is a very flexible backbone that provides the principles under which nations can operate together, to define how some new phenomenon like satellite constellations fits under the expectations of a spacefaring nation," he said.

Constellations are not a new concept in space exploration, but they have been proliferating in recent years due to the ability to launch fleets of small but capable satellites on a single rocket. The most cited concern is the SpaceX Starlink constellation, which has an estimated 1,630 operational satellites as of July 2021, according to calculations from McDowell, and is growing fast.

"We started the SATCOM workshops after the launch in May 2019 of the first tranche of Starlink satellites," SATCOM2 co-chair Jeff Hall, an astronomer at the Lowell Observatory in Arizona, said during the press conference. 

"That led to the idea we should all get together, in a community sense, and see what might be done about some of the impacts on astronomy. We know these satellites are perhaps up to a billion times brighter than the faintest objects astronomers study and have a significant impact on ground-based observatories, which require pristine dark skies to perform their research."

SpaceX eventually hopes to have as many as 42,000 Starlink satellites providing broadband service, and more companies are looking to grow their own fleets, including Amazon's Project Kuiper (which has yet to launch any craft) and OneWeb, which has already lofted 254 operational satellites.

Lowenthal praised some satellite companies for being "significantly and substantially involved in the planning of this workshop," along with promising to "commit resources" to reduce the effects of satellite constellations. 

That said, he pointed to challenges. There are no firm regulations yet forcing companies to adjust their satellites to help astronomy observations, he said. Further, the competition has already been tough and resulted in bankruptcies. While Lowenthal did not name any particulars, one commonly cited example is OneWeb's recent Chapter 11 proceedings and subsequent ownership change.

"Even the business model is on shaky ground," he said. "We've already seen bankruptcies, and having a completely unregulated atmosphere is not necessarily the best for them, either. I think there's broad agreement that regulation is going to happen. Of course it's a slow process, but that's what we're launching with this workshop."

More than 350 astronomers, satellite operators, space policy specialists and advocates for dark skies — skies with a minimum of light pollution and satellite interference — attended SATCON2 from 40 countries, representatives said. A final report will be available around the end of September.

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Elizabeth Howell

Elizabeth Howell is a contributing writer for Space.com who is one of the few Canadian journalists to report regularly on space exploration. She is the author or co-author of several books on space exploration. Elizabeth holds a Ph.D. from the University of North Dakota in Space Studies, and an M.Sc. from the same department. She also holds a bachelor of journalism degree from Carleton University in Canada, where she began her space-writing career in 2004. Besides writing, Elizabeth teaches communications at the university and community college level, and for government training schools. To see her latest projects, follow Elizabeth on Twitter at @howellspace.