Satellites and Light Pollution: The Fight for Ground-Based Astronomy

by Rebecca Schembri, Harvard University, August 26, 2021

Humans have looked to the skies since the first night they could see stars. As civilization progressed, astronomy became an important field of study—a way for humans to calculate information about life on Earth, and to better understand their origins by studying the Universe. After thousands of years, humans now know where life comes from, how it flourished on Earth, and what is required to maintain it. By using telescopes to look deep into the cosmos, the study of the night sky has become more than an intrigue—it is life-saving science. Now however, such science is threatened by technological advancement: light pollution from cities and human-made space objects are interfering with telescope and radio observations. If the problem grows, it will mean the end for ground-based astronomy. Although talks to mitigate the dilemma have opened, current laws do not offer a clear advantage, and much must be done to save the dark and quiet skies from falling victim to prosperous and ambitious commerce.

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Light pollution is “causing a lot of headaches for astronomers,” says Jonathan McDowell, an expert from the Harvard-Smithsonian Center for Astrophysics. The problem is twofold. First: tens of thousands of objects are being launched into Earth’s orbit, causing hindrances in studying the night sky. To provide global internet services to 3 billion humans, companies such as Starlink and OneWeb have plans to place a myriad of satellites in outer space, with China adding an additional 13,000 by next year. These devices “will be at a problematic high altitude for astronomers,” McDowell says, “and others will be at a low altitude which will be problematic just for looking at the night sky.” Obstructions will be present both in telescope images, and to the naked eye. As astronomers strive to avoid trails of light streaking through their images caused by reflections from satellites, the problem, if it continues, will become much worse: avoiding trails every 20 minutes is manageable, says McDowell, but if the obstructions occur every moment from every angle, it is not something scientists can deal with: “If there isn’t some kind of management of the night sky,” he worries, “we are going to lose ground-based astronomy this century.” The profession will become a casualty of technical and commercial growth.

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In a recent plea for a moratorium on satellite launches, European astronomers express their disapproval, saying “the deployment of large fleets of small satellites planned or ongoing for the next generation of global telecommunication networks can severely harm ground-based [astronomy].” In their article “Concerns About Ground Based Astronomical Observations,” led by S. Gallozzi (Rome), the astronomers request legal recourse for damages caused by Starlink, saying the investments made to fund their research are being exploited. These damages, they claim, are potentially permanent for observatories if regulations are not set in place. Soon every area of the night sky will have a satellite in it, and the Earth will lose its cosmic perspective.

Satellites and Space Debris / Credit: National Geographic

Dr. Alissa Haddaji is a Harvard Professor and member of the United Nations Planetary Defense Working Group. She sees this issue going beyond harmful interference and damages for liability—it is a global sustainability threat. She believes there is more to worry about with the satellites being placed in higher orbits since they are dependent on fuel to reenter Earth’s atmosphere: “The Low Earth Orbit satellites are not as worrisome,” she says, “since they will eventually deorbit, but the ones going into Medium and High Earth Orbit could have complications coming back down, and they have much potential of adding to Earth’s space debris, creating an environmental issue.” With Earth’s current orbital space debris comparable to 23,000 metal baseballs, 500,000 metal marbles and golf balls, and 100,000,000 metal snowflakes swirling in orbit at 17,000 miles per hour, adding more gadgets to space is non-intuitive and could trigger Kessler Syndrome—an event like a high-speed racecar crash, when one piece of debris creates a chain-reaction of multiple crashes. The event would surround the planet with uncontrollable objects, making it impossible to access space for generations.

Arizona’s Kitt Peak / Credit: VisitTucson.org

Because of this, ground-based astronomy is in a dangerous place: “It would be technically reasonably straightforward to launch enough bright satellites to permanently ruin our work,” says McDowell. Eventually, astronomers will not be able to compete with orbital satellites and space debris. An example of this threat is happening today at the ALMA observatory in Chile. Because of its location, satellites are continuously in its view, and the observatory may become obsolete in making breakthrough discoveries such as in 2019, when the telescope played a fundamental role in capturing the world’s first image of a black hole.

Space Debris | ESA
Satellites and Space Debris / Credit: ESA

Not only do satellites pollute astronomy images, they also impede detection of approaching asteroids and comets, creating a security risk for humans. “All satellites,” writes Gallozzi, “will be particularly negative for scientific large area images used to search for Near Earth Objects, predicting and, eventually, avoiding possible impact events.” If telescopes cannot see incoming asteroids, the whole world is at risk by Potentially Hazardous Objects entering Earth’s atmosphere, and time-sensitive mitigation will not be an option. In general, at least four months of reaction time are needed to avert an incoming PHO and depending on the method used to either push or pull the object, years of global deliberation and preparation may be necessary.  Incoming PHOs are as their name denotes: potentially hazardous to life on Earth. An asteroid just 100 meters wide could cause a perpetual winter, as its impact dust would shade the sun’s light, killing plants on a global level and leaving the survivors to die of suffocation and starvation.

Comet NEOWISE 2020 / Credit: Kevin Morefield, Getty Images

After satellites, the second problem for astronomy is local light pollution, which is growing faster than Earth’s human birth rate. Due to economic and technological development, cities everywhere are employing more and more lighting, which is why astronomer Richard Green of the University of Arizona Steward Observatory is alarmed. At this year’s Dark and Quiet Skies conference, he explained that “rapidly growing artificial skyglow is putting the world’s observatories under threat.” As looking into a flashlight makes it impossible to see what is beyond, ground-based observational astronomy is affected by bright lights from sports arenas, billboards, casinos, and security lighting—all products which symbolize modern-day advancement. This is a hit on more than just science: advocates to keep the skies quiet and dark say growing skyglow will affect star and astro tourism as complete industries fashioned around looking at the night sky are threatened.

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Legally, there is not much that can be enforced until regulations emerge. A review of international law shows this is an issue between the launching countries and the countries whose astronomy is being obstructed. The current treaties include the Outer Space Treaty—which states that space is for all humankind; the Liability Convention—which holds accountable those who cause damages; and the Registration Convention—which makes the launching country responsible for the launchers. Although international law provides legal protection for countries to sue each other over scientific damages, it is not a practical course of action. Not only do cases at the International Court of Justice take over a decade to resolve, bickering between nations is a primordial answer, says Simonetta Di Pippo of the United Nations Office of Outer Space Affairs. She cautions that “it is not the time for unilateral actions when we are all affected by the challenges we face.” Before pursuing legal disputes, astronomers rallying to have a voice at the United Nations must focus on international awareness and on global support.

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Part of this is the U.N.’s Educational, Scientific, and Cultural Organization’s campaign to preserve the night sky and astronomical heritage of humanity. Supporting the endeavor is the Dark and Quiet Skies annual event sponsored by the International Astronomical Union and UNOOSA. The conference’s mission is to secure international space sustainability guidelines for the world to follow. Organizers are lobbying for the U.N. Committee On the Peaceful Uses of Outer Space to start talking about ground-based astronomy as something that is in its jurisdiction. Oddly, astronomers are now forced to get involved in U.N. deliberations—a process which is not usually in their job description. But “without international regulation,” McDowell says, “there’s nothing stopping someone else from putting something worse up there.” The astronomy community must make a presence at the law-making table.

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Nationally, the American government has the power to protect astronomy, as it does within the National Radio Quiet Zone in Green Bank, Virginia—a town where wi-fi, cell phones, and microwave ovens are illegal because they interfere with the radio frequency science being conducted there. However, the observatory is overseen by laws that are a “special case” and do not blanket all of U.S. astronomy. With Starlink, the question is whether expensive business attorneys are persuasively keeping lawmakers from preserving the night sky, or if the government values internet access more than pictures of outer space. This is highlighted in the 2015 Space Resource Exploration and Utilization Act, a law the U.S. Congress passed allowing companies to bypass bureaucratic “red tape,” encouraging them to emerge as space commerce leaders in remote sensing—satellites—and in space mining.

Green Bank Observatory / Credit: REX Features

Whether big money or big government is winning has yet to be proven. But the conversation for saving the night sky is promising on other levels: many groups are supportive of regulation, and common interests have united the front. For example, not only is Light At Night bad for astronomy, according to doctors it is unhealthy for humans. The American Medical Association has announced that LAN is linked to mood disorders, obesity, diabetes, diminished performance, and to prostate and breast cancer. Also, improper lighting causes “nightglare” which creates nighttime driving disability in seniors due to changes in their eyes after age fifty. This can be remedied with better engineering of streetlights. Advocate groups are educating local authorities on the monetary savings from using lighting that does not illuminate the night sky—but instead lights downward the areas needed at night—and in lighting curfews and motion-sensor devices. Therefore, grassroots regulatory frameworks to reduce growth of light pollution are helping astronomy, and they are good for citizens; for skyglow and LAN, local and state municipalities are learning that it is healthier, more appealing, and less expensive to use efficient lighting.

Dark and Quiet Skies
Traditional Lighting vs Environment-Friendly Lighting / Credit: Dark and Quiet Skies

Another argument against LAN is that it damages the bio-environment. Sea turtle babies hatching on the Florida coastline, for example, instinctively crawl to the reflective nighttime ocean to find food and habitat, yet with bright oceanfront lighting they seek out the structures along the beach instead—residences and businesses—and die. Many species are suffering confusion, accidents, and illness as LAN grows. Not only is damage to biodiversity a human threat, as ecosystems are intertwined with human survival rates—but with satellite and light pollution, it is a question of space and environmentalism: to what extent is near-Earth space a part of the environment and already covered by environmental legislation? As a human rights issue, there is no international law making the night sky a heritage to humans. UNESCO, however, argues there should be as they declare natural resources, environmental sustainability, and freedom from pollution the birthright of future generations. The counterargument is that global internet could be viewed as a human right since it contains access to education, employment, and healthcare: items denoted in the Universal Declaration of Human Rights. The question here becomes: which is a greater right to humanity? Stars or internet? The argument has legal earmarks on both sides.

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Technologically, sharing the night sky with obstructions is not an easy solution. Funding and innovation are needed for software improvements, which can eliminate light trails in pictures, but the accuracy of the information will still be diminished—such as in determining the precise brightness of a star when a light streak has imposed itself on the take. “It can’t solve the problem, but it can make images look ‘less bad’,” says McDowell, who is an expert in dark sky light pollution. Advancements in hardware, on the other hand, can be fitted to large observatory telescopes to adapt a triggering shutter which closes for 5 seconds when a satellite goes by, but will be much more expensive than changes in software. McDowell does not believe technology will solve this issue—not only would it be grossly expensive—in the billions—to retrofit every telescope in the world, but it is also not the true answer. Technology will not help if there are satellites always coming at all sides. On this issue, talks between interested parties have opened and they have helped: “there are technical regulations that could limit the number of satellites of certain brightness, which is the compromise coming out in the long run,” says McDowell, “but it’s got to be something that the whole world decides, not just one company or one regulatory agency in the US.” For lasting change, balance on all sides will be key.

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The constant study of the night sky is bound by the awe that comes from seeing things greater than one—to consider how miraculous life is, and to calculate for its continuance. “If humanity loses its cosmic perspective, we are lost,” wrote Derek McNally, a man who spent his life studying the night sky. Twenty-five years ago, he foresaw the dangers that would threaten his field and warned that something needed to be done before it was too late. Although moves are being made to help earth-bound astronomy survive, it will take a team of advocates across multiple disciplines to convince lawmakers that serious consequences are at hand and must be mitigated. Light pollution and satellite placement are more than a threat to ground-based astronomy, they are a security issue, a health issue, an environmental issue, and a humanitarian issue. “The real thing for us, says McDowell, as he Zooms in from a networking conference with satellite companies, “is to not have the night sky grossly changed based on the decisions of any one country.” He speaks like a true academic, and one who loves the stars enough to fight for access to them. The conversation to save ground-based astronomy has begun, and although it may find opposition before it finds a consensus, there are enough good arguments to reach a fair agreement.

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Rebecca Schembri is an undergraduate student at the Harvard University Extension School. She lives in Reno, Nevada, USA.

Special thanks to Drs. Alissa J. Haddaji and Jonathan McDowell for interviews.

Sources available upon request: RebeccaFromReno@gmail.com.

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