Elon Musk’s SpaceX has established itself as a leader in the satellite industry, boasting over 7,000 satellites in orbit as part of its ambitious Starlink internet constellation. With plans to expand this fleet to as many as 42,000 units, each satellite is designed to have a lifespan of approximately five years. To sustain a constellation of this magnitude, astrophysicist Jonathan McDowell estimates that SpaceX would need to launch an astounding 23 satellites daily while simultaneously deorbiting the same number to ensure they burn up in the atmosphere.
While SpaceX leads the charge in satellite launches, it is not alone in this burgeoning sector. Amazon.com Inc. recently joined the fray with its Project Kuiper, launching its first 27 production satellites into orbit under the leadership of Executive Chairman Jeff Bezos. This move aims to create a competitive internet constellation that rivals Starlink. The growth in the satellite industry is staggering: last year saw the deployment of more than 2,800 satellites, a dramatic increase from the 500 launched in 2019, according to McDowell's analysis from the Harvard & Smithsonian Center for Astrophysics.
As satellites in low-Earth orbit eventually deorbit, they rely on the upper atmosphere to incinerate their remains. This process, however, highlights a significant gap in current environmental regulations, which primarily address pollution from human activities at Earth's surface. Concerns are rising that the pollutants falling back to Earth could contribute to environmental issues, similar to the impact of carbon dioxide and ozone-depleting compounds. Research into stratospheric pollution is an emerging field, and early findings indicate that the emissions from rocket fuel and falling satellites might hinder decades of progress in restoring the ozone layer and could also alter weather patterns.
Projections suggest that the number of satellites in orbit could surge from approximately 12,000 today to between 60,000 and 100,000 within the next five years. By 2035, Goldman Sachs predicts that the value of the satellite industry will balloon to $108 billion, up from the current $15 billion. “We’re right now at that point that we see there is a problem coming,” warns Kostas Tsigaridis, a research scientist at Columbia University’s Center for Climate Systems Research.
Despite being designed to burn up upon reentry, treating satellites as disposable poses its own challenges. The debris generated still needs to be accounted for, akin to industrial waste. Although the current amount of material in the upper atmosphere is not alarming, scientists are already experiencing a sense of déjà vu reminiscent of past environmental crises.
In the 1970s, experiments revealed that various factors, including emissions from supersonic jets and chemicals in everyday products, were harming the ozone layer. The discovery of a substantial hole in the ozone layer in 1985 prompted swift action from governments and industries, resulting in a ban on harmful substances. As a result, the ozone layer is expected to recover fully by the mid-2060s. However, the rapid growth of the satellite industry threatens to undermine this significant environmental success.
Experts, including Martin Ross from the Aerospace Corporation, have raised alarms about the pollution resulting from this rapidly expanding industry. “Unlike with aviation, emissions produced by the space industry affect every layer of the atmosphere,” Ross stated. The initial analysis of the satellite industry's impact began in the late 2010s; however, researchers did not foresee the impending satellite boom. Data from 2020 to 2022 revealed a stark increase in satellite launches and debris, surprising scientists like Connor Barker from University College London.
The environmental consequences of satellites begin even before they reach orbit. The kerosene used to fuel many rocket launches burns less efficiently at higher altitudes, generating soot pollution that contributes to climate change. Research indicates that around 80% of the black carbon produced by rocket launches is deposited at altitudes of 15 kilometers or higher, where its warming effect is 500 times greater than at ground level. This black carbon can influence large-scale circulation patterns and cloud formation, compounding the challenges of climate change.
Another emerging concern is the potential for soot to accelerate ozone destruction by heating the tropopause, a boundary that separates the lower atmosphere from the stratosphere. This added heat could create a “leak,” allowing water vapor to rise into the stratosphere, further exacerbating ozone depletion.
Recent studies have quantified the presence of stratospheric aerosols containing launch- or reentry-related particles, finding that these account for about 10% of the total and are likely to grow as the industry expands. Researchers are also monitoring an increasing variety of novel chemicals in the upper atmosphere, including copper, lead, and lithium, which have been detected due to satellite vaporization.
One significant concern is the rising levels of aluminum in the atmosphere, a key material in satellite construction. While the exact amount used is often undisclosed due to trade secrets, estimates suggest that aluminum comprises 35% to 45% of satellite materials. This aluminum can react with oxygen to form aluminum oxide, which may contribute to ozone depletion. A recent study noted that falling satellites produced approximately 17 tons of alumina in 2022, a 30% increase from natural levels.
As the satellite industry continues to expand, companies are becoming increasingly aware of the environmental implications of their operations. Current U.S. regulations favor atmospheric reentry for satellite disposal, with the Federal Communications Commission mandating that spacecraft must reenter the atmosphere no later than five years after their mission ends. Alternatives, such as "graveyard orbits," are available but are not commonly utilized.
To mitigate environmental impacts, satellite manufacturers are exploring options to replace aluminum components with more sustainable materials. Additionally, some companies are adopting longer-lasting satellite designs to reduce the frequency of launches and minimize the amount of expired satellites in orbit. Nevertheless, the industry is yet to fully embrace a rethinking of its business model in light of ongoing research.
As the satellite industry continues to grow, experts like McDowell emphasize the need for more robust research and regulatory frameworks. “We don’t have to ultimately choose between deregulation and responsibilities for space sustainability and the environment,” said Jay Schwarz of the FCC. Although the current emissions from satellites may not pose a significant threat compared to past environmental issues, scientists caution against complacency. “We should not close our eyes now because it is small,” warns Tsigaridis.
