保护空间：环境问题、风险与责任

Safeguarding Space Environmental issues, risks and responsibilities Executive summary The space sector is growing exponentially, with over 12,000 spacecraft deployed in the pastdecade and many more planned as the world embraces the benefits provided by satellite services.This growth presents significant environmental challenges at all layers of the atmosphere. Theseinclude air pollution from launch emissions, spacecraft emissions in the stratosphere, spacecraftdemise, orbital debris (legacy and new) and increased risk of collision creating more debris; Monitoring of upper-atmosphere impacts remains limited. There is a lack of high-altitudeobservations, in-situ measurements and systematic tracking of re-entry emissions or resultingchemical changes. Weak coordination among actors (space agencies, scientists, engineers,industry) further hinders a full understanding of the scale, nature and significance of thesepotential risks. While space agencies, regulators and launching states have started implementing 1.Space activities are related to the advancement of scientific knowledge, research andexploration, and they also contribute to daily activities on Earth such as earth observation,communications, positioning, navigation and timing, which provides a wealth of monitoringdata about the Earth that is essential for advancing the Sustainable Development Goals.While 2.In the past six years, satellite launches and commercial space flights have surpassed those ofthe previous six decades(Karacalioglu and Stupl 2016; Christensenet al. 2018; Boley and Byers2021; Rao and Letizia 2022). Most recent spacecraft deployments have been in low earth orbit (LEO),with a large increase in spacecraft from so-called large constellations (built by rapid deployment 3.Atmospheric ablation (or “burn up”) is the removal of spacecraft surface material underintense heat and friction during re-entry, through processes such as vaporisation, melting andchipping.Similar effects are seen with meteorites: most burn up, but some fragments reach Earth.A key concern is the volume, composition and total mass of space debris and spacecraft re-enteringthe atmosphere at the end-of-life, since not all objects are expected to fully ablate—as evidenced byspace debris that has landed on Earth (The Independent 2025). Re-entry mass can be tracked via 4.This expansion, coupled with a reduction in satellite orbital decay lifetimes from 25 to 5 years(Federal Communications Commission 2022; ESA 2024c)to deal with congestion in LEO andreduce collisions, creates environmental impacts. With launch frequency rising, the urgency for 5.A number of organisations and researchers have highlighted the issue of the rapid increasein the launch of spacecraft globally and that emissions could impact atmospheric chemistryand stratospheric ozone specifically(Parket al. 2021; Clormann and Klimburg-Witjes 2022; Ryanet al. 2022; Maggiet al. 2023; United Nations Environment Programme [UNEP] 2023; Ferreiraet al.2024; Maloneyet al. 2024; Sharma 2024; UNEP 2024; Maloneyet al. 2025). The Scientific Advisory elements within the atmosphere(Becket al. 2019; Murphyet al. 2023; NOAA Chemical SciencesLaboratory 2023). Aluminium is widely used, and its anthropogenic contribution to the atmosphereis comparable with that coming from meteoroids (Boley and Byers 2021; Schulz and Glassmeier2021). Estimates show that the anthropogenic contributions of Aluminium have surpassed that fromnatural sources in 2024 (Ferreira and Wang 2025). Between 800 to 5000 metric tons of rocket bodies 7.The National Oceanic and Atmospheric Administration (NOAA) has matched the metal ratios inatmospheric dust with those of spacecraft objects, confirming their source(NOAA 2023). NASAflights have found that at ~19km altitude, 20 per cent of sampled particles contained spacecraft-specific elements, estimating that 10 per cent of stratospheric particles originate from spacecraftablation (Murphyet al. 2023). Trace metals—even at low concentrations—and particle size, are 8.Nearly 130 million pieces of orbital debris—from fragmentation events (explosions andcollisions), abandoned spacecraft, satellites and rocket stages, mission-related operationaldebris and intentional destruction such as anti-satellite weapon tests—pose escalating risks to 9.Elements from ablation are known to accumulate in polar regions due to the circulation patternin the upper atmosphere that sends particles from the Equator, where most objects re-enter,to the poles(Rosset al. 2009). Modelling concentration and where such materials would be found 10.Annual collision losses are estimated between US$ 86 million to US$ 103 million (Johnsonetal. 2023), underscoring the urgency of mitigation.While technical solutions for debris removalare emerging, international rules, regulatory, licensing and market incentives are essentially absent(McKnightet al. 2021). Efforts to remove legacy debris, including the 50 most concerning derelictobjects (McKnight