What is it about?
Examines the environmental footprint of human spaceflight, then asks who benefits from that footprint and who bears its costs. Space travel has substantial environmental impacts per person served, raising sustainability and fairness concerns—especially as commercial space tourism grows. Using a life cycle assessment framework, the authors estimated impacts from launch vehicle materials and manufacturing, propellant production, and propellant combustion. They compiled data on human spaceflight programs and launches from 1959 through 2021, including crewed flights and uncrewed supply missions that support people in space. They compared total impacts with the amount of time people spent in space.
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Why is it important?
Main findings - The estimated climate impact of sustaining human activity in space is about 1,500–3,500 kg CO₂-equivalent per person-hour in the authors’ low-to-high scenarios. - That is roughly 2,000–4,600 times the average global person’s hourly greenhouse-gas emissions. The paper also compares it to continuously supplying several megawatts of electricity or operating dozens of diesel buses. - Longer stays in space, such as on the International Space Station, reduce the estimated impact per person-hour compared with short trips. But long stays still depend on repeated supply launches, which create a floor on their impacts. - The authors estimate that launch requirements rise sharply with payload mass, making ambitious missions—especially those involving large payloads or destinations such as the Moon and Mars—potentially more resource-intensive. - Greenhouse-gas emissions are only part of the picture. The assessment also considers impacts such as acidification, toxicity, smog, and ozone depletion; which part of a launch contributes most varies by impact category.
Perspectives
The authors question the idea that space development will relieve pressure on Earth’s resources. In their view, space activity itself depends on substantial Earth-based materials, energy, and supply chains. They argue that the people able to travel are generally very wealthy, while environmental costs—including climate impacts and pollution near launch sites—are shared more broadly and may fall especially hard on vulnerable communities. They say proponents of expanded human space travel should make a clear case for benefits that extend beyond the travelers.
Dr Michael Carbajales-Dale
Clemson University
Read the Original
This page is a summary of: The environmental and moral implications of human space travel, The Science of The Total Environment, January 2023, Elsevier,
DOI: 10.1016/j.scitotenv.2022.159222.
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