Image courtesy of the European Organization for Astronomical Research in the Southern Hemisphere.
Far above the rush of everyday life, past our fragile atmosphere, and across millions of miles of space, billions of stars glow. While bright city skylines already make it difficult for people in urban areas to enjoy this beautiful night sky, a new source of light pollution is on the rise: satellite megaconstellations, also known as satcons. Satcons are collections of thousands of artificial satellites launched by commercial companies, and they are lighting up the night sky. Researchers from the University of Regina, University of British Columbia, and University of Toronto at Scarborough recently collaborated on a predictive model for the damage satcons will ultimately cause to their research and to the night sky.
In the last few years, researchers have seen the impacts of satcons grow both in their research and in their everyday lives. Astronomer Samantha Lawler moved to Saskatchewan in 2019 for a faculty position at the University of Regina and was able to see the Milky Way from her home for the first time. But she saw something else as well: a growing number of satellites whizzing by due to Starlink, a satellite constellation operated by SpaceX with the stated goal of providing worldwide internet service. “I knew from my calculations that this [was] going to be a big problem for a lot of areas of research in astronomy,” Lawler said.
Astronomers often collect data by using telescopes to take pictures of the sky in different wavelengths of light, such as visible, infrared, and radio. However, the recent increase in satcons has resulted in an increasing number of images being contaminated by satellite streaks. While this can currently be corrected for by taking several images of the same patch of sky, this restorative measure will become increasingly unreliable as more satcons are launched and more images are contaminated. Even telescopes in space aren’t immune to satellite contamination—the historic Hubble Space Telescope has to contend with it as well. The future James Webb Space Telescope will be one of only a few telescopes free from their influence, due to its more distant orbits.
The brunt of the impact of satcons will likely be felt by astronomers who study the skies in visual wavelengths. As images become more and more filled with satellite streaks, they will contain fewer and fewer pixels of data that are actually useful to researchers. For example, the Vera Rubin observatory, a nearly $500 million facility in Chile, has predicted that thirty percent of its images will be severely impacted by satellite trails. “The same science goals [in visual astronomy] can happen, but they’re going to take longer,” Lawler said.
Other types of astronomical research will feel the impact of satcons as well. Near Earth object observations, which involve monitoring for asteroids potentially dangerous to our planet, will become much more difficult as satellites are mistaken for asteroids. Radio astronomy will also be hit hard as commercial satellites begin making noise at frequencies currently reserved for research.
In most fields of astronomy, it will simply take more data over more time to reach the same findings. But getting access to telescopes and observatories to take data is already incredibly competitive for researchers. “It just means that fewer people are going to be able to get science results. We don’t actually know what we’re going to miss, and that’s pretty sad,” Lawler said.
To get an idea of the damage satcons will cause, Lawler and two other researchers created a model based on reflectivity estimates and launch filings to the Federal Communications Commission (FCC). Their model allows anyone curious to enter a latitude, time of day and year, and several other factors, and view an estimate of what satcons will affect their night sky. It is freely available at http://megaconstellations.hanno-rein.de/.
In creating this model, researchers faced the major challenge of modeling the reflectivity of satellites without specification information from the companies. As such, they used a classic physicist trick: modeling every object as a sphere. This allowed for surprisingly successful predictions, creating data that matched with observations better than more complicated attempts. They also had to balance countless other complex factors, including distribution models for orbits. But their work will pay off: such an accurate model will be extremely useful to other researchers going forward.
It’s worth questioning how this problem could be fixed instead of simply modeled better. At first glance, there seems to be an easy solution: regulate the corporations launching the satcons. But unfortunately, no regulations currently exist for low Earth orbit. At the moment, industry is voluntarily having some discussions about the issue: this July, the National Science Foundation hosted SATCON 2, a conference to facilitate conversations between astronomers and satellite operators. But “it just became incredibly clear during the meeting: you [corporations] don’t have to be here. You don’t have to talk to us,” Lawler said.
Companies are ultimately under no obligation to respect the night skies, and never will be without a major change in international regulation, which would take years to implement. Meanwhile, SpaceX continues to rapidly launch satellites into space. “My hopes are not enormously high that [regulation] will happen fast enough,” said Hanno Rein, an astrophysicist at University of Toronto at Scarborough.
Satcons are also causing enormous environmental problems. Their launches release an incredible amount of carbon into the atmosphere.
And that’s not the end of the damage they can cause. SpaceX alone plans to have 42,000 satellites that will be replaced every five years, meaning that they will have to deorbit more than twenty satellites per day. These satellites will burn up in Earth’s atmosphere, depositing six tons of aluminum and other materials into our upper atmosphere daily and wreaking untold environmental havoc.
One measure could help prevent this fate: the global recognition of low Earth orbit as an environment. This would force environmental impact assessments to be conducted for these satellites, giving governments a better idea of their potential damage to the atmosphere.
While researchers would much rather return to their preferred areas of study, satcons are not going away—so unfortunately, neither is research into their effects, including their climate and environmental impacts. For example, teams have begun to look into what huge quantities of deorbiting satellites might imply for Earth’s atmospheric chemistry. Research may also need to examine the biological implications for animals that rely on the night sky for navigation.
Astronomers will continue working to mitigate the effects of satcons on their research, including attempting to lower the numbers of satellites launched. Additionally, they will advocate for satellites to be launched into orbits minimally destructive to research. Finally, they will aim to make satellite-impacted research as useful as possible—for example, work is being done to perfect algorithms to remove satellite damage from images. “Someone could describe it as chemotherapy for your images. It’s not great, not ideal, but it’s better than nothing,” Lawler said, attributing the phrase to astrodynamicist Moriba Jah at the University of Texas Austin.
Unfortunately, while these strategies help mitigate the damage wrought by satcons, they can never fully undo it.
The benefits brought by Starlink and other satcon services are certainly worthy of acknowledgment. But only a tiny fraction of the world’s population will be able to afford these services—Starlink internet service currently costs $99 a month, plus a $499 upfront cost. This creates a familiar system where wealthy countries reap the rewards of technological advancement while the entire world feels its negative consequences. A tiny portion of the Earth will gain faster internet service, and an even tinier portion will line their pockets. But untold volumes of astronomical research—and perhaps more tragically, the sheer beauty of the clear night sky—will be lost to all.