Insight: Clearing the Air: Understanding and Engaging on Possible Atmospheric Impacts of Space Activities

In recent years, several studies and articles have been published providing preliminary scientific evidence indicating that space activities, including emissions resulting from both space launch and from space objects burning up during reentry upon disposal (a process known as atmospheric ablation), may have impacts on Earth’s atmosphere. These potential impacts include negatively affecting ozone levels, increasing solar reflectivity, and altering cloud properties and atmospheric density. As the number of spacecraft reentries increases in line with the growth in space activities, the need to mitigate any possible negative impacts on the atmosphere may be in tension with existing space sustainability best practices for post-mission disposal and design for demise. But the scientific work is in early stages, and much uncertainty remains. At the recently concluded 7th Summit for Space Sustainability, this topic was a major theme of discussion: exploring both the current state of scientific knowledge in this area and the role that the space sector can take in addressing gaps in that knowledge.  

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During the 7th Summit for Space Sustainability, José P. Ferreira, a researcher at the Department of Astronautical Engineering at the University of Southern California, who has focused on the possible atmospheric impact of spacecraft ablation, gave a short presentation summarizing the current state of scientific knowledge of the possible atmospheric impacts of spaceflight activities and the uncertainties therein. Ferreira reported that 2024 was the first year in which it is known, with a 95% confidence level, that the amount of aluminum deposited in the atmosphere as a result of spacecraft reentries was more than that resulting from natural sources, such as meteors. The potential impact, adverse or otherwise, from this change remains unknown, as Ferreira stated, “This doesn’t mean there is a negative environmental impact, but it allows us to acknowledge that there is a change in the status quo.”

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Secure World Foundation (SWF) also recently contributed to a study, funded by the United Kingdom Space Agency (UKSA) and led by the University of Southampton, on the topic of the environmental impacts of atmospheric ablation of spacecraft. This study, which also included the University of Edinburgh and Space Forge, focused on establishing a comprehensive technical and policy research framework aimed at mitigating the possible environmental risks associated with atmospheric ablation of end-of-life spacecraft. Results of the study, one of several funded by the UKSA on related topics, were published in October 2025.

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Broadly speaking, this study finds that, based on the number of spacecraft expected to be disposed of through atmospheric ablation by 2033, significant amounts of alumina, silica, and other metal oxides could be released, leading to measurable loss of ozone.  However, the study also outlines a number of uncertainties around this effect and its impact on the atmosphere, including:

• Understanding of the specific size and distribution of the metal oxide particles released during ablation (e.g., do they: stay local to where reentry occurs; distribute in the atmosphere globally; concentrate at certain altitudes; concentrate in certain regions).
• Understanding of the duration of particle persistence in the atmosphere (and at what altitudes).
• Detailed knowledge of the specific species, alloys, or types of alumina and silica used in satellites, and at what amounts, and how they interact with other materials in the atmosphere.
• A lack of in-situ observations of reentering objects to better inform and validate simulations.
• Assessment of the magnitude of impact as compared to other industries and activities.

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Reducing these scientific uncertainties requires interdisciplinary work involving materials science, atmospheric science, and physical and chemistry science. However, current research to assess the sources, magnitude, and potential adverse impacts of spaceflight activities on the atmosphere is being conducted in a dispersed, uncoordinated manner. This research is being carried out by space agencies, atmospheric agencies, and science foundations, as well as academia, in several countries with little formal coordination or info-sharing. While there are ad-hoc forums for exchanges of technical information, such as workshops convened by the European Space Agency and between the United Nations Office for Outer Space Affairs and the United Nations Environment Programme, there is not, either at the national level or at the international level, a formal strategy for coordination and sharing of findings. Nor is there a systematic and coordinated research program in place. This lack of coordination extends to the involvement of industry stakeholders and actors. Spacecraft manufacturers and operators may consider materials data to be proprietary or commercially sensitive and may have concerns about reputational impact if sharing material data leads to them being perceived as environmentally irresponsible.

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Addressing this emerging challenge requires both technical and non-technical advances. Broader coordination is required across technical agencies, regulators, and industry. On the day prior to the 7th Summit for Space Sustainability, SWF and the UKSA co-hosted a workshop on the topic of atmospheric ablation. This event, which included subject matter experts from industry, government, and academia, focused on the presentation of the key outcomes of the atmospheric ablation studies funded by the UKSA and then featured roundtable discussions to identify opportunities or challenges and consensus on further action. A summary report from this workshop is forthcoming. Key takeaways include: 

• There is a lack of understanding across the community into this issue and the potential scale of the problem, including gaps in current understanding of the behavior of metal oxide particles in the mesosphere. 

• There is a need for more reentry data and improvement in observation and measurement capacity to understand the problem.  

• Further research is needed to identify knowledge gaps and provide an evidence base for decision making. 

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In this discussion, it was generally recognized that while the possible impacts of spaceflight activities on the environment are a growing area of concern, it was also acknowledged that scientists do not know the magnitude of effects from rocket launches and satellite reentry emissions. A common theme running through the discussion in this workshop, the studies SWF has been part of, and the panel and presentations during the 7th Summit for Space Sustainability, was this blend of uncertainty and concern. This creates a set of circumstances which leaves responsible operators and policymakers alike in a position of being unable to act. In general, there is not sufficient evidence to act, either for the development of policy and regulation, or for spacecraft operators/manufacturers to adopt mitigation actions. During conversations at the 7th Summit for Space Sustainability, most stakeholders noted that, given the lack of evidence and remaining uncertainties, it is likely premature to pursue regulation around these potential impacts. Yet participants in these discussions express a recognition that the issue may be significant and that understanding needs to be increased over a relatively short period of time.

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This leaves a number of next steps required:

• First is to address the clear need to continue focused research into the scale and magnitude of the potential problem as well as reducing the noted uncertainties. This must be interdisciplinary in nature and will likely require investment from public agencies.
• Second is the need for increased information sharing around the materials used in spacecraft construction. This will require industry involvement, including spacecraft operators and manufacturers, and will likely need an approach which ensures information can be shared in an aggregate manner. It might also be complemented by efforts to increase observations of spacecraft reentry. There may also be a need to consider or develop incentive-based mechanisms or platforms to enable international information sharing around materials. 
• Third is the need for a focused effort to convene the regulatory, spacecraft industry, and research communities on a regular basis. This would serve to facilitate scientific exchange, enhance policy and operational capacity to understand and engage, and begin discussion of potential mitigation strategies.

Through these steps, policymakers and industry stakeholders would be better positioned to make informed decisions related to the impact of space activities on the atmosphere and how the issue relates to ensuring space activities are being undertaken in a sustainable manner.