Erasing the stars: Satellite megaconstellations are a mega problem for Earth and sky

Yahoo

04-04-2025

In some ways, the stars above us are the ultimate equalizer: we're all equally far away, we all share the right to look up at them; and, tiny glittering pinpoints that they are, when we contemplate that cosmic glow, our fractious lives seem so brief, so comfortingly insignificant, compared to the light years they've traveled to meet our eyes. Vast, dark expanses glittering with stars are the skies under which we evolved: every creature alive has countless ancestors who existed under the light of stars visible thanks to the velvety darkness of the night sky.
But industrialization has changed that, of course, by introducing light pollution that gradually erased the stars from view before the bright blue light of countless LEDs made the situation so much worse. And now, as the new space race heats up, spawning tens of thousands of satellites in orbit around the Earth, it only stands to make the visible night sky less so. Dimming stars are just one of many problems posed by satellites and especially megaconstellations, groups of hundreds or thousands of small satellites that work together to give us broadband internet and mobile connectivity.
Starting in the 1950s and up to 2019, there was a sum total of roughly 2,000 operating satellites in orbit. But in May of 2019, Elon Musk's aerospace company SpaceX launched the first megaconstellation, Starlink, with an initial 60 satellites. (The small satellites that make up a megaconstellation launch in groups, with Starlink for example typically sending up 50 small satellites at a time.) But since that fateful launch, several thousand other satellites have made their way into orbit, with many, many more on their way.
It's still not wall-to-wall satellites in low Earth orbit, but it seeming will be in the near future. (Astrophysicist Dr. Jonathan McDowell keeps a running list here.) The U.S. Federal Communications Commission has already approved well over 7,000 further satellites, and SpaceX alone is aiming to get tens of thousands of their own into LEO over the next decade.
"We have our version of the famous 'hockey stick' plot from climate change, where the temperature is up, steady, steady, steady and [then] rapidly increasing. That's what's happened in space due to satellites," Dr. James Lowenthal, a professor of astronomy at Smith College in Massachusetts who, in his work, observes young galaxies so distant that their light has traveled billions of years to reach us, told Salon in a video interview. The projected figures are the definition of exponential.
"Now there are over 10,000," Lowenthal said, almost entirely relating to Starlink. But other companies are increasingly vying for real estate in orbit. "There are over 200 projects [in the works], each of them with dozens to tens of thousands of satellites. The Starlink project ... has filed for plans to put in place some 40,000 satellites in low Earth orbit."
Most of the non-SpaceX projects are private companies, too. But governments also want to reclaim their previous dominance of space, and everybody wants in.
"India, China, Brazil are all close behind. The United States military is developing its own [megaconstellations] right now," said Lowenthal. "The nation of Rwanda has filed plans for 330,000 satellites. Whether that comes to fruition or not, it's impossible to predict. But there are hundreds of plans, and the numbers of satellites filed are now at least 500,000 heading towards a million within the next ten years."
These satellites perform valuable services to humans on Earth and even, in some respects, to other living things — for example, by helping us monitor planet-heating emissions. In fact, recent research suggests they will be key to improving our data on CO2 emissions. Dr. John Barentine, an astronomer, dark sky consultant and historian of astronomy in Arizona, even pointed to the background image he uses for video calls as he spoke with Salon: it's a global composite image of Earth made by remote sensing platforms in space. "Without them," he said, "we would not have anything approaching the understanding of the problem that we do have."
But weighing those benefits against the various harms of vast numbers of shiny bodies whirling around the earth is already enough to push dark sky lovers into action. Over the next ten years, our night sky may be irrevocably transformed by the projected legions of satellites.
This affects the casual stargazer, both those of us straining to reconnect with nature on occasional camping trips in the wilderness and those of us who like to look for stars even in the city, longing to see shooting stars or the great spangled expanse of the Milky Way, but making do with a nice bright Venus or Orion's Belt on a clear night.
"What you'll see is the satellites moving across the sky. Those are just reflecting sunlight, just [like] the way the moon is reflecting something. The moon is not shining by itself, it's shining some reflected sunlight. So satellites do the same thing whenever they're in sunlight," Lowenthal explained. The more of them there are, the more shine you'll see. But satellites also shine in two other ways, which laypeople won't notice."One, they actually do have a little bit of their own temperature. They're actually glowing in the infrared. So if you turn a sensitive infrared telescope to them, you see them. They're also emitting radio frequency radiation. That's how they communicate with each other and with the ground by usually short wave, or microwave radiation," Lowenthal said.
This level of interference has been noticeable by radio astronomers for a while. It's manageable for now, but then, the numbers of satellites in the sky are a mere fraction of projected numbers within the next few years.
"I don't think you could talk to a professional astronomer, an observer, who hasn't had satellites go through their images lately," Lowenthal said. "There are papers now, already, that had been published and then retracted, because it turned out that what we thought was a really cool thing was just another satellite."
Such really cool things have included a near-Earth asteroid. "Nope," Lowenthal went on, "it turns out it was that Tesla car that Elon Musk launched into orbit around the sun. That will only happen more often."
Beyond Tesla cars photobombing astronomical images, both amateurs and professionals have been photobombed by numerous non-vehicular Starlink satellites, including an image of the comet Neowise and others. Victims even include the low-orbiting Hubble Space Telescope.
The use of the radio spectrum is regulated internationally by the Radiocommunication Sector of the International Telecommunication Union, which publishes regulations allocating frequency ranges for different services or uses such as astronomy, remote sensing, communication and navigation, and also provides thresholds on power flux densities not to be exceeded by other services. The ranges allowed are narrow, far more restrictive than the sort of electromagnetic compatibility standards used on Earth, and unintended electromagnetic radiation can leak from electrical devices and systems on satellites.
For astronomy, the protected range is 150.05 to 153 megahertz. Research published in 2023 showed that emissions measured from dozens of satellites on the Starlink constellation exceeded their intended and allowed thresholds, interfering with the frequencies allocated to radio astronomy. They actually exceeded typical electromagnetic compatibility standards used for commercial electronic devices, too. Now, research published in September showed that the second generation of Starlink satellites also has this problem. And it's 32 times worse.
Satellites aren't currently the main source of light pollution that affects our view of the night sky. But given enough time, they may be — and to a very significant degree. While dark sky advocates have had some success getting individual jurisdictions to begin working towards mitigating the effects of terrestrial light pollution, mitigations are in no way keeping pace with the rate at which low earth orbits are being colonized by these zipping, flashing celestial bodies.
There are working satellites in space, and there are non-functional satellites: what's called space junk or space debris.
It's getting cluttered up there. In fact, the issue of space debris is older than the concern about megaconstellations. Dr. Aparna Venkatesan, an astronomer at the University of San Francisco whose research focuses on cosmology and the re-ionization of the universe after the Big Bang, is a committee co-chair, and Lowenthal and Barentine are committee members, of the Committee to Protect Astronomy and the Space Environment, an advisory committee of the American Astronomical Society. Since 1988, COMPASSE has addressed both ground- and space-based light pollution and radio interference, Lowenthal said, "and the threats attended to use and overuse of space, namely space debris. What happens when things start crashing into each other. And there's just, whenever we do activities in space, there's always some debris associated with it. It's noticeable. Now it's going to get much worse, then what are the effects of it?"
One of those effects can be light. Not only because of especially bright satellites, but just because of their sheer numbers.
"It's like many, many thousands of rotating, glinting ruffled potato chips, basically," as Venkatesan put it. "This glinting, rotating cage of hardware that, first of all, don't cause a streak alone, but are rotating and have a little glint that can throw off a lot of areas of astrophysics, like time domain astrophysics, that look for variable phenomena."
"To their credit," said Lowenthal, "SpaceX has spent millions of dollars on this, and they've had several engineers devoted to this problem."
They've tried things like applying darkening treatments to the satellite. They've tried giving the satellite a visor. They've tried a new coating that is super-dark. But nothing has been enough to solve the problem.
Right after launching, a bunch of satellites heading to join the megaconstellation looks like a string of moving stars going up in the sky. Within a week or so, they reach a higher elevation and are less visible. But they're still not faint enough, despite six years of effort, Lowenthal said.
Additionally, there's the problem of debris from satellites crashing into each other or trash that orbits — everything from droplets of fuel to flecks of paint and other tiny bits of things that float around the Earth at 5 miles (8 km) per second.
"It's a thin haze that reflects sunlight down and makes the sky look artificially bright," Lowenthal said — Venkatesan describes it as a fine dust — noting that some recent research suggests that if debris keeps tracking with the amount of satellites, the night sky as viewed from anywhere on Earth could become several times brighter, perhaps even too bright for astronomical observations to be made at all.
As well as brightening the sky and interfering with astronomy through their flashes and radio waves, satellites pollute the atmosphere on launch and on re-entry, as research from last October underscored. In 2021, the International Astronomical Union issued a report drafted from the work of 85 scientists that aimed to provide recommendations for how astronomy might be protected from the visible and radio impacts of satellites as well as from terrestrial sources of light through policy changes at local or international levels. When they talk about astronomy, this means that a large part of their focus is on protecting the remote sites where large telescopes and observatories are set up around the world from electromagnetic interference. But it's not just such remote sites that are impacted by satellites, which exert effects on the local and global environment both at launch and at re-entry.
Rockets have long been known to pollute the atmosphere in various ways. Depending on the type of rocket fuel used, launches produce nitrogen oxides, chlorine, black carbon particles, water vapor, carbon monoxide and carbon dioxide — and no propellant avoids creating of some kind of emissions.
"There's a lack of policy regarding the environmental impacts of these megaconstellations," Dr. Connor Barker, a research fellow in atmospheric chemistry and physical geography at University College London, told Salon in a video interview. The many satellites now heading up to space don't live long: these days, they're designed to have a five-year lifespan to reduce the amount of trash in orbit. Getting them out of orbit means they re-enter the atmosphere, burning up — but not without a trace. In October, Barker and co-authors Eloise Marais and Jonathan McDowell published a multi-year inventory of air pollutant emissions and CO2 from rocket launches and object re-entries spanning the early growth of the megaconstellation phenomenon from 2020 through 2022.
Such data, he explained, is very challenging to compile. Barker and his team used multiple sources to put together their inventory, crosschecking information they found in different sources against launch livestreams and studies previously conducted by other researchers. Along with gaseous reactive nitrogen, satellites burning up as they re-enter the atmosphere at the end of their lives leave tiny particles of aluminum oxide, imperilling the still-recovering ozone layer. Chlorine (which reacts with the aluminum) and nitrogen oxides also drive ozone depletion.
"We're starting to see that we might be reversing some of the gains we've made from the Montreal Protocol through these increased rocket launch and re-entry rates," Barker said. So reducing debris in space might mean increasing the pollutants in our atmosphere. In fact, it's a bit of a battle of priorities, as Barker explained to Salon. And despite the laudable role satellites play in monitoring greenhouse gas emissions, they contribute to them too.
"We're often dealing with large gaps in the data that we would want," Barker explained. Such gaps make it extremely hard to provide precise information about likely impacts. "For rocket launches, we don't even know sometimes how much fuel is used by the rocket or how much the rocket weighs or what altitudes the rocket operates over. Sometimes we get that information from American or European launch providers. It's extremely hard to get that information for Chinese launches. And then even harder if you're looking at something like North Korea. So there's a real lack of information that having all of that data would make our estimates more accurate."
The researchers also have not had any direct contact with Starlink, which typically does not provide access to the data they use to make their own estimates and sustainability claims. Salon reached out to Starlink for comment via SpaceX, but did not receive a response.
"It's proprietary, so they don't want another company to take the data. The place you usually get the data from is a user manual — a document used by people that want to launch a satellite, and that will contain details about the rocket," Barker said.
The multiple authors of a December paper published in Nature's Communications Earth and Environment note that "Satellite technologies are essential for global conservation actions through providing continuous, real-time Earth monitoring." The fact that even recent research on the impact of International Dark Sky Places on light pollution relies on observations made from orbiting satellites should make the point. However, the huge increase in rocket launches needed to get all those satellites up there (there were 223 launch attempts in 2023), places a significant and growing strain on the various life forms and biomes where launches take place.
Right around the rocket launch site, local ecosystems are affected by explosive emissions, acoustic oscillations, and land and water use for installation. Meanwhile, the exhaust from rocket boosters and the shuttle cloud itself can cause local damage to vegetation. Fuel spills, chemical leaks, intense noise levels, and acid deposition all lead to loss of local biodiversity — but local in this case means up to 45 km (28 miles) from the launch site. The authors of the Communications Earth and Environment paper cite, for example, research showing hydrochloric acid emitted from solid rocket launches killing fish after it leached into nearby water. They note that over 62% of operating sites are located within or close to protected natural areas.
Falling debris from separating rocket parts extends the affected area to encompass 400 to 1,500 km (249 to 932 miles) from the actual launch site. That's of course not including emissions that become part of the atmosphere and circulate around the globe. And a rocket that blows up can shed debris over huge areas of ocean or land, as demonstrated by a SpaceX test launch that exploded early in March, raining debris over the Caribbean Sea and grounding flights around the globe.
So far, most efforts to reduce all these effects and their growing impact involves voluntary mitigations, not significant regulation. The main and in fact only legal framework for international space law is the U.N.'s Outer Space Treaty. Article IX states that: 'States Parties to the Treaty shall pursue studies of outer space, including the moon and other celestial bodies, and conduct exploration of them so as to avoid their harmful contamination and also adverse changes in the environment of the Earth resulting from the introduction of extra-terrestrial matter and, where necessary, shall adopt appropriate measures for this purpose.'
Two or three problems become evident here. For one thing, this treaty refers to states. Not corporations, not individual billionaires, just states.
"The Outer Space Treaty was really intended to apply to governments," Lowenthal said. "And I don't think the writers of the OST foresaw what we have today, which is essentially something akin to a gold rush or the discovery of oil or the building up of the railroads: tremendous infusion of investment by private interests, also by governments, to help promote the development of a new industry that is seen as potentially an economic driver."
Writing in Northwestern Journal of Law and Policy in 2023, Yuree Nam said that "the space industry and governments have shifted focus away from preventing mass destruction in space. Instead, the space industry is now concerned with private actors commercializing spaceflight and private companies trying to develop commercial activity on Earth and in outer space."
There is other relevant legislation and policy in addition to international space law, of course. But as well as sharing Lowenthal's concerns with the inadequacy of the OST to address the current reality, Nam argues that domestic regulation in the U.S., under the Federal Aviation Administration, is also not up to the job. Though the agency provides licenses to private space companies wishing to launch rockets, environmental review is only a small part of the permitting process. (Satellites being burned up in the atmosphere after five years in orbit is a requirement of FAA licenses under American law.)
Satellites in orbit communicate down to ground stations using radio signals regulated by the Federal Communication Commission. Of course, under the new administration it is possible that much of this will be reorganized. Lowenthal says that an Office of Space Commerce may take over some of the regulatory role of both the FAA and the FCC; all this remains to be seen.
Inadequacy for dealing with private companies is one problem. Another is that the language of the OST refers to avoiding contamination of the moon and other celestial bodies, as well as adverse changes in the environment of the Earth resulting from the introduction of stuff from space. It doesn't refer specifically to all of the issues posed by satellites, including contamination by light, which comes from light-emitting sources on Earth or else from the sun. The sun isn't to blame for light pollution that brightens the night sky, though — we are.
A third potential problem with the language and scope envisioned by the OST is that it doesn't define a geography that captures the creation of light pollution in the night sky, wherever that is exactly, from the perspective of organisms on Earth.
"We think of light pollution as a local issue, and we are lacking a domestic light pollution strategy or a national light pollution policy at present," Venkatesan said. "But even though light pollution can be a local issue, its effects are global."
Not just global, but exponential: the issue of brightening skies, and the other problems of satellites, are both global and growing far more quickly than responses to them in the form of policies, regulations or laws, not to mention monitoring and oversight.
"The challenge with quite so many satellites up there isn't just the changing [atmospheric] chemistry, the sheer numbers, the sheer pace at which they're being launched," noted Venkatesan. "It's that it's happening in parallel with the unchecked firing of a lot of branches of federal agencies that are keeping track of this."
One of the early DOGE layoffs, Venkatesan added, was at NOAA, and involved staff that oversee the traffic coordination system for managing space traffic. Another was in the commercial remote sensing regulatory affairs division, affecting the staff responsible for oversight of remote sensing from space that allows us to understand the scale of the problem of light pollution down on Earth.
"We are not fundamentally opposed to the development of space," Barentine told Salon. "What we are concerned about is the way that it's proceeding."