The Future Crisis in Space: The Threats to the Ozone Layer and Safety Posed by Satellites and Space Debris

The Future Crisis in Space: The Threats to the Ozone Layer and Safety Posed by Satellites and Space Debris

2025年10月24日 00:31

Right above the Earth, in low Earth orbit (LEO), a "quiet mass extinction" is occurring. Small satellites that have completed their missions are re-entering the atmosphere and burning up almost daily—releasing alumina (aluminum oxide) particles that could delay the recovery of the ozone layer. The rapidly increasing space debris poses the greatest risk to the safety of the ISS and communication satellites. The article from Phys.org dated October 22 summarizes researchers' warnings and challenges us to reconsider our "responsibility in using space."Phys.org


What's the problem: "New Load" in Numbers

  • As of summer 2025, there are over 14,000 satellites orbiting the Earth. The total number of launched objects exceeds 20,000, with a combined mass of 50,000 tons. According to ESA estimates, 10,000 tons still drift in orbit.Phys.org

  • The ISS performs avoidance maneuvers at least once a year. Even small fragments traveling at 7 km/s can be fatal.Phys.org

  • Small satellites average 250 kg. It is said that they can release about 30 kg of alumina upon burning up, which could disrupt stratospheric chemistry.Phys.org

  • According to a U.S. research team's scenario, mega-constellations could add 360 tons of alumina to the atmosphere annually. There could be a time lag of several decades before the effects become apparent.Phys.org

On the other hand, a simulation assuming stricter assumptions with an annual alumina emission of 10,000 tons (10 Gg/yr) suggested a maximum warming of 1.5°C in the stratosphere to mesosphere and a delay in ozone recovery. Although there are various assumptions, the lower and upper bounds of the risk are rapidly becoming concrete.csl.noaa.gov


Is "burning up" the optimal solution: Impact on the ozone layer

When aluminum-based satellites burn, they produce Al₂O₃ (alumina), which may affect ozone destruction reactions and radiation balance in the upper atmosphere through interactions with chlorine and nitrogen oxides and optical properties. Past observational and modeling studies have also reported that metal particles from re-entry can remain in the stratosphere for a long time.Science


Furthermore, rocket emissions cannot be ignored. A study published in Nature in 2025 concluded that chlorine and black carbon from solid fuels could delay ozone recovery. The scenario involves the overlapping of two burdens: satellite re-entry and rocket emissions.Nature


Impact of Mega-Constellations

Starlink alone has launched about 8,000 satellites since 2018, with approval for a total of over 40,000. Amazon's Kuiper and other national constellations follow.Re-entry assumes "safe burning up," but the sheer number of cases creates new externalities.Phys.org


Public commentary and investigative reports have also begun to visualize the explosive increase in satellite numbers and metal aerosol pollution in the upper atmosphere.Bloomberg


Realism in Space Security

From the perspective of researchers and operators, debris is the "greatest risk." Fragments of centimeter size are particularly dangerous, and if they hit inhabited areas, they can cause instantaneous fatal injuries. There have been cases where the ISS's robotic arm developed a puncture hole.Phys.org


ESA advocates a **"Zero Debris" approach, strengthening the obligation for post-mission disposal plans (deorbiting or transferring to a graveyard orbit). However, as long as the **"burn and disappear" method** externalizes the burden to the stratosphere, the trade-offs remain.Phys.org


How did social media react: Three voices from the field

  • "Re-entry has become 'routine'"
    Posts reporting re-entries at a pace of 1-2 per day, such as footage of burn-ups over Canada in September, have proliferated, and videos of visible fireballs have spread. Astronomers' observation threads are also active.EarthSky

  • "Calls for regulation and international cooperation"
    On social media and news sharing platforms, there is a persistent call for addressing concerns about the Kessler Syndrome and the absence of regulations, as well as for establishing international rules. Discussions have expanded by quoting explanatory articles and expert comments.Tom's Hardware

  • "Counterarguments seeking comparison with natural origins"
    On platforms like Reddit, there are suggestions that comparisons should be made between metal influx from meteorites and industrial origins. The scientific community is advancing verification based on differences in total amount, particle size, and altitude distribution.Reddit

What should be done: A practical roadmap

  1. Aluminum-free design/coating
    　Support research on material design to reduce Al₂O₃ production during re-entry, and change the properties of generated particles through surface treatment and multilayer thermal shielding.

  2. Redesign for "complete deorbit"
    　Consider standardizing control of disintegration altitude and **recovery and reinsertion (controlled re-entry)** to minimize reactions in the upper atmosphere.

  3. Mandatory LCA (Life Cycle Assessment)
    　Make the quantitative evaluation of atmospheric chemical impacts from launch→operation→end-of-life processing a certification requirement.

  4. Transparency and observation
    　Open up re-entry logs, composition, and combustion models. Continue upper atmosphere observations and model assimilation by NOAA and research institutions.csl.noaa.gov

  5. Traffic management and orbital hygiene
    　Enhance collision avoidance AI and ground monitoring, and optimize fuel efficiency for avoidance maneuvers to fundamentally reduce debris generation and re-entry incidents.


Conclusion: Earth's atmosphere is not a "final disposal site"

The benefits created by satellites in communication, observation, and security are immeasurable. However, the notion that **"burning up renders them harmless"** is no longer valid.The thin air at high altitudes is an invisible infrastructure of modern society and also an organ that takes time to recover.Now, when scientific uncertainty remains, we should steer towards design, operation, and regulation based on the precautionary principle.Phys.org　Nature



Reference Articles

Satellites and Space Trash Threaten Ozone Layer and Space Safety
Source: https://phys.org/news/2025-10-satellites-space-trash-threaten-ozone.html

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