Researchers are fighting back against the harm done by satellites

SpaceX, the Starlink Satellites, and the IAU/CAFCO Mission: a global conversation on the radio astronomy and space debris problem

Satellites allow people in remote areas to use phone calls while online without the need for ground-based infrastructure. The Starlink network of telecommunications satellites, which is the largest of its kind, has been booming during the past decade. Between 2017 and 2022, companies requested access to the radiofrequency spectrum for more than one million satellites.

This success is accompanied by mounting concerns about safety and the environment. As things stand, most satellites are single-use products with a lifetime of 15 years or less. Moreover, space debris is a growing problem, as physicists Richard O. Ocaya at the University of the Free State in Bloemfontein, South Africa and Thembinkosi D. Malevu at North-West University, Potchefstroom, South Africa, describe in a Comment article. The satellite boom raises key questions about whether humanity could or should clutter the environment around Earth without regulation.

The Vera C. Rubin Observatory, perched atop a mountain in Chile, will begin surveying the universe with the largest camera it has ever built. It will produce a map of the southern sky every three nights, with lots of stars, asteroids, and bright satellites ruining some of the view.

The IAU team also helped to raise awareness of dark and quiet skies at a meeting of the United Nations Committee on the Peaceful Uses of Outer Space in Vienna last month, the first time that the issue had been formally discussed at a global level. Also in February, Chinese astronomers and satellite operators met with US and European researchers to share ideas on how radio astronomy and satellites can coexist. Any conversations that occur should be encouraged.

The first step is raising awareness. Finance is another. The center was run on a shoestring because of in-kind contributions and free time donated by astronomer. Last year, the IAU was given a US$750,000 grant by the National Science Foundation to create software tools to predict when satellites will appear in telescopes.

Then there’s the role of those who build and fly satellites. As the biggest operator, with more than 7,000 satellites, SpaceX, based in Hawthorne, California, has commendably led the way by working with astronomers to reduce the impact of its satellites on Rubin and other observatories. Other companies should do the same. This could include releasing more information on satellite specifications and the frequencies of their radio transmissions. Much of this information is commercially sensitive, but at least some could be shared in ways that would still be useful to astronomers, with proprietary details redacted.

International discussions need to recognize the rights of Indigenous peoples in space as well as on Earth, says Hilding Neilson, a Mi’kmaw astronomer at Memorial University of Newfoundland in St. John’s, Canada. He says that the UN should recognize Indigenous rights in outer space. “If you’re going to destroy the night sky through light pollution or satellite pollution, that’s colonization,” he says.

How far are satellites from an observatory? The fight against the swarms of satellites (This is how researchers are fighting back)

The number of satellites has increased in the last five years due to the fact that they provide internet access around the globe. OneWeb, a space communications company in London, has more than 630 satellites in its constellation, which is more than the number of operational Starlink satellites launched by SpaceX in Hawthorne, California. On paper, tens to hundreds of thousands more are planned from a variety of companies and nations, although probably not all of these will be launched1.

Knowing when and where a satellite will pass over an observatory is the first step to reducing satellite interference. “The aim is to minimize the surprise,” says Mike Peel, an astronomer at Imperial College London.

One of the centre’s tools, called SatChecker, draws on a public database of satellite orbits, fed by information from observers and companies that track objects in space. SatChecker can be used to confirm what a satellite is doing. The tool isn’t perfect; atmospheric drag and intentional manoeuvring can affect a satellite’s position, and the public database doesn’t always reflect the latest information. For instance, the BlueWalker 3 satellite from telecommunications firm AST SpaceMobile in Midland, Texas, launched in 2022 and was sometimes brighter than most stars; yet uncertainty of its position was so great at times that astronomers had difficulty predicting whether it would be in their field of view for their night-time observations2.

SpaceX took early steps to try to mitigate the problem. The company tested changes to the design and positions of Starlinks in order to keep their brightness beneath a threshold. Amazon, the retail and technology giant based in Seattle, Washington, is also testing mitigations on prototype satellites for its planned Kuiper constellation. Such changes reduce, but don’t eliminate, the problem.

Source: Swarms of satellites are harming astronomy. Here’s how researchers are fighting back

SCORE: a large-scale open data database for space-tracking astronomy with solar sails, wind, and high-energy radiation

Marco Langbroek is a space-tracking specialist at Delft University of Technology in the Netherlands and he says that the database is very valuable because it is one of the few that have data freely available. As a beta tester, Langbroek has added a number of entries to SCORE, including measurements of a NASA solar sail that changes in brightness as it tumbles through space. Going forwards, he says, SCORE will be most useful if a lot of astronomers contribute high-quality observations to the database, thereby building up a resource over time.