The Atmospheric Impacts of Re-entry and Launch (AIRL): High Priority Actions and Recommendations

Whitepaper: Outcomes of the AIRL Working Group, urgent short-term research priorities including measurement campaigns to fill knowledge gaps.

Spaceflight activities have expanded at an unprecedented rate over the last decade, leading to satellite launch rates being 10 times higher today than 10 years ago. The growing number of orbiting objects is increasing the risk of accidental collisions, threatening the long-term usability of key orbital regions. To mitigate the orbital risk, current industry standards and institutional regulations now require active and passive end-of-life de-orbiting. They also promote “design-for-demise” approaches, ensuring that satellites ablate (disintegrate) completely upon re-entry to minimise the ground-casualty risk. However, the environmental risks of space activities extend beyond just the orbital environment and Earth’s surface. Rocket launches and the ablation of re-entering spacecraft release a variety of gases and particles directly into the middle and upper atmosphere. These emissions include metallic and carbon-rich particles and gases that are chemically and radiatively active. As the frequency of launches and re-entries increases, so do the amounts of these emissions. Yet their distribution, their physicochemical evolution, and radiative properties remain poorly understood with little available data, leaving their broader atmospheric impacts uncertain. Furthermore, tracking where these emissions are ultimately deposited at the Earth’s surface is needed to assess potential toxicity and effects on ecosystems. The pace at which the space sector is expanding far outstrips our ability to evaluate its environmental footprint. Addressing the scientific knowledge gaps urgently requires a coordinated programme integrating targeted atmospheric observations, ground-based experiments, and advanced modelling. This will allow us to comprehensively characterise the emissions from space activities and better understand their impacts on, for example, ozone depletion, atmospheric radiative balance and climate forcing. Such work is critical for solid, evidence-based environmental assessments and for developing effective mitigation measures, including alternative propellants and engineering requirements for future missions. Over the past year, the Atmospheric Impacts of Re-entry and Launch (AIRL) working group has developed a detailed research programme and implementation roadmap to close the most pressing and relevant science gaps. We propose this programme as a proportionate, low-cost risk-reduction effort to assess the environmental risks. It builds on existing assets and partnerships, prioritising coordination and transparent data sharing. Key actions include acquiring high-quality experimental and observational data that can be rapidly integrated into plume and ozone-climate models, and fed back into toolchains and regulation and licensing processes. The outcome will provide the scientific, policy-ready, actionable information that enables the sustainable growth of the space sector. The following items are critical, short-term recommendations that require urgent funding commitments.

Authors & Editors:
AIRL WG and participants from the 2nd Workshop Atmospheric Impacts of Spacecraft Launch and Re-entry (23-25 September 2025)
Overview · Indico at ESA / ESTEC

The work was mandated by the ESSC Chair.