Implementing Circular Economy Strategies for Sustainable Space Operations: A Comprehensive Review

Kurzfassung

Current space practices are predominantly linear, leading to significant resource depletion and debris accumulation. Approximately 7,000 tons of material, including valuable metals, plastics, and ceramics, are wasted while also contributing to the growing problem of space debris and increasing risks such as the Kessler syndrome, where collisions generate more debris, leading to further collisions. Moreover, existing end-of-life disposal methods are unsustainable, offering limited options: either leaving spacecraft in orbit or disposing them through graveyard orbits or atmospheric re-entry within specified timeframes (i.e. one year for controlled re-entry and up to 25 years for uncontrolled re-entry). However, the emergence of in-orbit operations presents a promising opportunity to transition towards circular economy (CE) strategies in space. These in-orbit operations refer to activities conducted by spacecraft in outer space and include operations such as maintenance, repair, refueling, upgrading and recycling of other space objects while they remain in orbit. The latter would facilitate the recollection of rare materials potentially used in satellites, which serves as an additional motivator for the implementation of CE strategies. Integrating CE strategies in space also faces specific challenges, which are already being tackled, including advancing the state of the art in enabling technologies, overcoming regulatory hurdles, and securing adequate funding and stakeholder support. Additionally, the economic viability of these practices, particularly regarding material preservation and reuse, has already been demonstrated by Leonard and Williams (2022). To further the development of sustainable space practices, it is crucial to understand and define CE in the context of space. This poses significant challenges, necessitating a clear clarification of what CE entails for space operations and how it can be effectively integrated into the existing framework. Establishing the connection between CE strategies and space is essential in order to identify the specific benefits that such integration would bring, including resource efficiency, cost savings, and reduced environmental impact. This raises the key research question: how can circular economy principles be effectively applied to the space sector to improve sustainability? To address this, the chosen approach involves a comprehensive review of current and prospective space activities that embody or align with CE principle. By systematically examining the existing literature on these practices within the space sector, this research aims to delineate a clear framework for integrating CE strategies into space missions and operations. This research highlights the necessity of using Life Cycle Assessment (LCA) to evaluate the environmental viability of CE practices. LCA provides a systematic approach to assess the environmental impacts of space operations and can help identify opportunities for improvement in the design, manufacturing, and disposal phases of spacecraft. Additionally, the review identifies specific CE strategies for the space sector, such as designing spacecraft for disassembly, promoting reuse and recycling, and developing technologies for in-orbit servicing and repair. Adopting these strategies can reduce space debris and extend spacecraft operational life, thereby enhancing the overall sustainability of space missions. Ultimately, this study seeks to enhance understanding of the intersection between CE strategies and space operations. By integrating more CE strategies, the research will contribute to the long-term sustainability of space exploration and utilization. This will help preserve the orbital environment and ensure space remains a viable resource for future generations. Through adopting CE strategies, the space sector can lead by example, demonstrating how innovative and sustainable practices can be implemented in one of the most challenging environments.