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Reusable launch vehicles (RLV) are slowly emerging as a solution to reduce space access costs, bringing potential benefits from novel breakthrough space application. Whilst space presents an ideal platform for addressing global issues, it raises an "adaptation-mitigation dilemma". Launch vehicles are the only anthropogenic object emitting directly into every layer of the atmosphere, and reusability may introduce additional burdens. Although it may ensure a rational use of materials through the recycling of major components, its potential sustainability gains with respect to equivalent expendable launch vehicles (ELV) has not been quantified. The correct understanding of these are therefore critical to ensure sustainable design choices for space transportation. This study reviews current state of knowledge on launchers environmental impact and eco-design before introducing a preliminary life cycle and atmospheric impact assessment of the different technologies for first stage reusabiltiy. Reusabiltiy showed possible early reductions in material resource depletion which was independent of propellant choice and recovery strategies. In terms of climate forcing, reusability was only beneficial when fully carbon neutral propellant production was assumed for hydrolox, ammolox technologies, and possibly for methalox if soot production is kept under sustainable limits. VTHL performing In-Air-Capturing recoveries also showed reduced climate forcing potential. Stratospheric ozone depletion potential was estimated to increase by 18-34 % for VTVL vehicles, and 12-16% for VTHL with respect to ELV. In addition, high sensitivity with mixture ratios, flight profiles, staging condi- tions and aerodynamic capabilities was identified, which require detailed assessments with higher fidelity design methods. Future launch impacts from large scale space activities were also estimated to no longer be negligible, although some margin for mitigation exists among the various design options, and recent regulatory developments internalizing climate change costs might significantly affect the business case of RLVs. In addition, high altitude atmospheric impacts, particularly those from soot emissions, appear to dominate the potential life cycle impact and uncertainty, especially for hydrocarbon fuelled launch vehicles. This is further exacerbated by the commonly used but unsuitable weighting based on aviation and ground based emissions. These might affect the absolute and relative comparisons significantly and therefore, results from this study must be taken with caution. Future studies should employ state of art atmospheric modelling and adequate approaches to weight the various life cycle impacts, enabling design for mitigation while avoiding burden shifts.

Within the European space sector, heightened interest in Life Cycle Assessment (LCA) has been stimulated by an increased motivation and urgency on quantifying environmental consequences of space activities. The associated growth in the application of this method places a greater emphasis on obtaining high levels of transparency, reliability and validity of all ensuing environmental claims. As such, the purpose of this study is to present a potential pathway for effective space-specific environmental communication and reporting. The paper outlines the results of a scoping exercise designed to map the specificities of the space sector against the ISO 14025:2006 standard on environmental labels and declarations. This was based on a literature review conducted to obtain the current state of knowledge within the space industry whilst drawing upon the procedures and experiences of other sectors, with particular consideration to Product Environmental Footprint Category Rule (PEFCR) development. The findings from this activity have been used to formulate a harmonised framework for environmental communication and reporting purposes in the context of the European space sector. The framework provides a comprehensive set of voluntary operating procedures which intend to act as preliminary guidance for European industrial stakeholders and national agencies. The paper goes on to discuss potential future framework refinements and provides a list of recommendations to advance sectoral practices further. This includes a call for the establishment of an industry specific platform to enhance the harmonisation of LCA development and ensure rigorous verification and validation of environmental claims.

Space debris mitigation has become essential for the continued use of space. The removal of satellites from Low Earth Orbit by uncontrolled atmospheric re entry is a recommended space debris mitigation practice. However, to ensure this is safe, Design for Demise processes are required to predict the risk of a satellite surviving re-entry using re-entry analysis tools. These tools tend to under-predict the risk of satellite re-entry due to limited success recording flight data on early re-entry missions. The most prevalent uncertainty in re-entry analysis tools that is yet to be measured is satellite fragmentation. As such, STRATHcube, a student-led CubeSat project for Space Situational Awareness developed at the University of Strathclyde, aims with its secondary payload to provide flight data investigating the conditions under which solar panel fragmentation occurs. This experimental payload aims to utilise the flexibility a CubeSat platform provides, developing and testing an initial framework for on board satellite monitoring during atmospheric re-entry. In this paper the initial design and development of this experiment is addressed. A discussion of the challenges encountered when designing a CubeSat for re-entry studies is also undertaken. These challenges include limited available mass, power, and volume inherent to a CubeSat mission, as well as satellite instability, communication blackout and high aerothermal and dynamic loads experienced during re-entry. The sensor platform developed to monitor the solar panels and record re-entry measurements for heat transfer, temperature, velocity, and attitude are also detailed. A trade-off between imaging and the use of electromechanical break switches to monitor fragmentation during re-entry is considered. With these activities, STRATHcube's atmospheric re-entry experiment aims to develop a framework for fragmentation studies, with the obtained flight data allowing for the greater validation and verification of satellite fragmentation in re-entry analysis tools.

This paper proposes a novel approach to the design of complex engineering systems which maximise performance, and global system resilience. The approach is applied to the system level design of the power system for future Moon bases. The power system is modelled as a network, where each node represents a specific power unit: energy storage, power distribution, power generation, power regulation. The performance and resilience of each power unit is defined by a mathematical model that depends on a set of design (control) and uncertain variables. The interrelationship among nodes is defined by functional links. The combination of multiple interconnected nodes defines the performance and resilience of the whole system. An optimisation procedure is then used to find the optimal values of the design parameters. The optimal solution maximises global system resilience where an optimal resilient solution is either robust, i.e. it is not subject to disruptive failures, or recovers from failures to achieve a functioning state, albeit different from the starting one, after a contingency occurs. The power system supports a Lunar base developed within the ESA-lab initiative, IGLUNA, led by the Swiss Space Centre. The power system, developed at the University of Strathclyde as part of the PowerHab project, is composed of nine interconnected elements: a hydrogen fuel cell energy storage system, a thermal mass storage system, a lithium-ion battery storage system, a constellation of solar power satellites (SPS) working in conjunction with a microwave wireless power transmission system, a reflecting satellite constellation and a ground-based solar power array. Distinct space and ground segments are identifiable, with orbit, AOCS and reflecting satellite nodes cooperating to provide optimal performance of the SPS constellation. The ground segment encompasses the ground-based solar array, energy storage systems, Lunar habitation module and the power transmission lines connecting these elements. Power generation is predominantly supplied by the ground-based array, with the SPS constellation and energy storage systems complementing this source; as well as providing redundancy and a reliable power supply during the Lunar night period.

For space-based solar power (SBSP) to be considered as a truly viable renewable energy technology, there should be a clear environmental benefit gained from its application. Additionally, given the scale of investment and engineering development, the price of energy must remain comparable to terrestrial-based generation systems for commercial feasibility. For this reason, a process-based life cycle sustainability assessment (LCSA) study was conducted to identify the life cycle environmental, economic and social impacts of the 1978 DOE/NASA Solar Power Satellite (SPS) Reference System. This was one of the first ever LCSA studies for space systems to be performed worldwide and was applied using a new LCSA tool for space missions developed at the University of Strathclyde. Taking a burden-based approach, the tool has been used to calculate environmental impacts across a wide range of different environmental impact categories and quantify costs over the system life cycle. The inclusion of social impacts adds additional depth to the analysis by showcasing the sociological impacts of the system on various stakeholder groups in line with the 2030 Agenda for Sustainable Development. The calculated life cycle impacts were then analysed further to identify potential hotspots through multi-criteria decision analysis (MCDA) and by measuring the results against annual global impacts (AGIs) and planetary boundaries (PBs). Life cycle CO2e emissions and costs were then compared to terrestrial energy generation systems in order to benchmark the relative performance of the technology as part of the conventional energy mix. The results suggest that whilst the DOE/NASA SPS Reference System can generally be described as a ‘green’ and ‘cost-effective’ system, several design improvements can and should be made to lessen its life cycle impacts. Therefore, it is proposed that the identified hotspots are used as a baseline for comparison or as mission drivers to continually improve future SPS designs.

With the role of concurrent engineering (CE) becoming more important to the success of companies, it is vital that engineering students are able to understand and apply this concept. In this regard, the University of Strathclyde regularly offers its students opportunities to learn about this process through practical-based CE workshops. The results from a student-based CE study of a CubeSat are therefore outlined, including the effectiveness of the session as a learning experience for students. Through collaboration and teamwork, the student team produced a feasible design concept which achieved most of the prespecified objectives. Additionally, it was determined that the learning outcomes of the study were widely met, despite it taking place virtually due to COVID-19.

Social distancing measures introduced in the wake of COVID-19 greatly impacted the concurrent engineering process. This paper addresses methodological adaptation measures which are required to ensure the continuity of this activity. Two CubeSat feasibility studies run at the University of Strathclyde, one physical and one virtual, are compared to quantify the impact of the adaptation. Three evaluation criteria are used: the fulfilment of requirements & customer satisfaction, server data flow rate and participant perceptions. The results indicate that although adaptation was successful, it failed to lift all communication barriers introduced by virtual exchanges.

Life Cycle Assessment is an important environmental management technique that is increasingly being applied within the space industry to assess the environmental impacts of products over their life cycles. However, with a renewed focus on sustainability issues, the space sector may need to move to a more encompassing sustainability assessment. In this regard, the new open source Strathclyde Space Systems Database is the first Life Cycle Sustainability Assessment tool for space systems. The use of this database is demonstrated by comparing different monopropellants in two separate scenarios. From this it is clear that the added sustainability dimensions can dramatically assist decision-makers to select more sustainable products.

Recent commitments by national and international bodies towards environmental problems has allowed a range of mitigation measures and key sustainability issues to filter down and become embedded in a growing number of industrial and commercial sectors. Notwithstanding this, space operations have often been overlooked in key legislation or regulatory requirements, with the result that the environmental impact of such activities were often disregarded or ignored. Over the last few years things have begun to change as interest has intensified in the transparency and accountability needed from the space industry in order to fully understand and articulate its effects on the environment. This has led to the development of an environmental management tool called Life Cycle Assessment (LCA) which is increasingly being adopted by the space industry to assess the full environmental impact of their products and practices over their entire life cycle. The European Space Agency (ESA) began work on this topic in 2009 by employing an internal concurrent design study called ECOSAT to consider the life cycle impact of the design, manufacturing, launch and operations of a satellite. One of the key findings of this study revealed that existing terrestrial focussed LCA databases lacked the scope and capacity to conduct such advanced assessments due to the unique and specialist nature of space sector operations. To overcome this, ESA has continued to develop LCA methodology within the space sector to the point where it is now looking at introducing it into the design of future spacecraft and space systems. This indicates the manner in which the design and execution of European space missions will likely proceed. Running alongside this green movement, the New Space trend is predicted to introduce large numbers of small satellites into the space environment which will substantially alter environmental and societal impacts. This paper presents an open-source LCA platform currently under development at the University of Strathclyde, outlining its integration into the concurrent design process of next generation green space systems. The LCA platform includes extreme scale systems from large constellations of nanosats to solar power satellites. Both extremes have in common the need of massive production cycles. The integration of LCA into the design process allows one to minimise the environmental impact and define new optimality criteria for the space system.