Assessing the space sustainability paradox: a life cycle assessment approach for eco-design and decision-making under uncertainty

The Space Sustainability Paradox highlights the tension between the benefits of space activities and their unintended impacts on both terrestrial and orbital environments. Addressing this paradox requires a multidimensional perspective that integrates environmental, economic, and social considerations in line with the Triple Bottom Line framework. This study applies Life Cycle Assessment (LCA) to space systems to provide a systematic evaluation of environmental impacts across all stages of development, enabling the identification of critical hotspots and guiding eco-design strategies in the early phases of mission planning. Leveraging the Strathclyde Space Systems Database (SSSD) as a source of Life Cycle Inventory (LCI) data and impact category definitions, the analysis computes sustainability scores at the midpoint impact level to support multi-criteria decision analysis (MCDA). Recognising the inherent epistemic and aleatory uncertainties in space mission design, a methodology for Uncertainty Quantification (UQ) is proposed, employing Dempster-Shafer Theory (DST) to properly characterise uncertainties at both the database and computational levels. The methodology is illustrated through case studies representative of preliminary mission trade-offs, quantifying uncertainties in LCA indicators to enhance decision-making, refine eco-design practices, and prioritise system-level considerations. By integrating UQ into sustainability assessment, mission designers are equipped to better evaluate trade-offs, mitigate risks, and optimise system performance under uncertain conditions. The findings provide a robust foundation for assessing the resilience, reliability, and adaptability of complex space systems, while advancing multidisciplinary , multi-objective optimisation of mission design. Ultimately, this approach establishes a practical framework for sustainability-driven strategies in space systems, with the objective of using these considerations to balance technological , economic, and environmental constraints for the responsible and sustainable use of outer space.