Could satellite mega-constellations trigger climate change 2.0? TEREZA PULTAROVA investigates.
The burgeoning space industry is raising new environmental concerns. Pollutants from rocket launches and incineration of satellites in Earth’s atmosphere could precipitate the next major environmental crisis. Space stakeholders are now scrambling to address these issues proactively.
Problematic Plumes
Hundreds of tonnes of dead satellites could be burning up in Earth’s atmosphere every year within the next decade. (University of Warwick/Mark Garlick)
Rockets introduce soot, carbon dioxide, and other pollutants into almost the entire atmosphere, a unique characteristic compared to other combustion technologies. Satellites, with mission lifespans measured in years rather than decades, end their service by burning up 60-80 kilometers above the Earth’s surface, leaving behind metallic ash. The high altitudes of these emissions mean their atmospheric lifespan is significantly longer, making their environmental impact more unpredictable.
Sebastian Eastham, a sustainable aviation researcher at Imperial College London, highlights the unknowns: “Anything you emit into the middle atmosphere can have impacts lasting up to a decade. We simply don’t know how much more impactful these emissions are per unit.”
Expanding Industry
Minkwan Kim (L) and Sebastian Eastham (University of Southampton & Imperial College London)
The space industry has seen a dramatic shift with the advent of small, affordable satellites and the promise of universal space access. From the 1940s with the V-2 rocket to the 1957 Sputnik, the space industry has been around for over half a century. The era of “New Space” has introduced an exponential rise in satellite launches and constellations. In 2010, fewer than 1,000 satellites orbited our planet, rising to over 11,000 by mid-2024. Over the past five years, the number of rocket launches has nearly doubled, driving up the amount of space debris burning in the atmosphere.
Minkwan Kim, Associate Professor in Astronautics at the University of Southampton, leads a project funded by the UK Space Agency to assess and mitigate satellite pollution. Kim warns, “If we address this early, we have a better chance to prevent serious issues, much like with carbon dioxide emissions, where early action could have avoided current global warming.”
Industry predictions are concerning. Applications for more than a million spacecraft suggest that between 60,000 and 100,000 satellites could be launched by 2030. With regular repletions of fleets, thousands of tonnes of space debris could be re-entering the atmosphere annually by the 2030s.
What Does It Mean for the Atmosphere?
As the skies turn extremely crowded, experts predict an increasing threat of space debris falling back on Earth. (McKinsey)
Annual re-entering space debris of around 3,600 metric tonnes might seem minor compared to the constant natural influx of meteoric material. However, spacecraft are primarily made of aluminum, which burns into alumina, a behavior distinct from meteorites. Alumina behaves like atmospheric sunscreen, reflecting sunlight and cooling the Earth, which could have unpredictable consequences aligning with but complicating global heating trends.
A study in Geophysical Research Letters found that alumina levels in the stratosphere could increase by 650%, leading to significant ozone depletion. Rocket exhaust compounds, including soot from RP-1 fuels, absorb heat and contribute to ozone loss, further complicating the atmosphere’s stability.
Kim adds, “Metallic dust could impact the Earth’s magnetic field, increase thunderstorms, disrupt satellite communication, and obscure Earth-observing satellites.”
The Space Industry’s Dilemma
ESA space junk map. (ESA)
Space debris is a well-known issue. Over 35,000 pieces larger than 10cm, along with millions of smaller fragments, pose threats to active satellites and potential collisions. The space community agrees on the need for timely removal of satellites—within 25 years from their missions’ end—an agreement that poses new challenges for the upper atmosphere’s cleanliness.
Legal Loopholes
An artist’s rendering of a satellite reentering Earth’s atmosphere. (ESA)
Rocket launches and satellite re-entries operate in a regulatory gap. Aviation has stringent emission rules, but there are no such regulations for rocket pollutants. The 1972 Liability Convention and 1967 Outer Space Treaty focus on liability, not atmospheric or environmental impacts.
Rachael Craufurd-Smith, a space and policy law expert at the University of Edinburgh, clarifies that existing treaties do not address environmental harm on Earth. Kim advocates amending the 1987 Montreal Protocol, which banned ozone-depleting substances, to include satellite disposal limits.
Is There a Way Out?
Addressing these concerns requires a multifaceted approach. Researchers are studying the long-term impacts of satellite pollution to develop mitigation strategies. Innovations in satellite design and engineering could lead to cleaner launch and re-entry processes. Additionally, stricter regulatory frameworks are necessary to ensure compliance with environmental standards.
The space industry must adopt a proactive stance, learning from past environmental crises like ozone depletion, and taking decisive action to prevent a new chapter in climate change.
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