Since the dawn of spaceflight, payload mass, or launched mass, has been used as the primary cost metric for mission-level trade studies. However, advances in the reusability and mass production of spacecraft have started decoupling mission cost from launched mass, leading us to consider novel metrics for trade studies and design of space systems. A new metric that is independent of launched mass will be especially useful to designers of complex space systems on the Moon or Mars where some of the system mass may be procured locally by way of in-situ resource utilization (ISRU). Further, since these worlds are hostile to complex animal life, technology and the sources of energy to build, maintain and operate it will be essential for all aspects of human life there. For these reasons, we propose an energy-based value and cost metric, Lifetime Embodied Energy (LEE), to replace launched mass as a useful proxy for the valuation and costing of infrastructure deployed, developed or operated on the Moon or Mars over long-term campaigns. Embodied energy principles have been used to calculate carbon footprints of Earth-based systems, however embodied energy does not and cannot underpin valuations of Earth systems or Earth infrastructure, largely because of the computational overhead imposed by the complexity, depth and breadth of terrestrial supply chains. However, space supply chains will be orders of magnitude simpler relative to whole-Earth networks, motivating the investigation into embodied energy as a universal metric. In this work, the lifetime embodied energy of a space system is the sum of the allocated portions of past and future, direct and indirect energy transformations that were or will be required to deliver the intended value from a system throughout its useful life. The starting points are a system boundary and a common energy source outside this boundary; this energy source can be the Sun, nuclear energy or, as used in the case study presented here, the embodied energy of space logistics. Then, the LEE framework was applied to a simple toy model of a 20-year campaign to Mars, featuring different combinations of energy, resource extraction and processing, manufacturing, assembly and habitat sectors. This model supported the comparison of Apollo-like campaigns vs. in-situ resource utilization (ISRU) alternatives. Using reasonable assumptions for model parameters, the results showed that over the same 20-year time horizon, Apollo-like architectures came in at a specific lifetime embodied energy cost of ~210 MJ/kg, but the best ISRU architectures cost under 70 MJ/kg. We further found that these reductions in specific lifetime embodied energy were correlated with increased up-front investment, increased absorption of in-situ resources and longer design horizons. Near-term applications include optimal design of multi-decade Moon or Mars campaigns, such as the development of large-scale industry, habitats and other persistent infrastructure on these worlds. Over the longer term, the LEE paradigm could serve as an objective costing and valuation system. Since LEE can, in principle, accurately value all space systems relative to each other, it can also serve as an anchored unit of measure, i.e. a currency, with which to settle space-to-space transactions in the emerging commercial space economy.


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    Title :

    Lifetime Embodied Energy: A Theory of Value for the New Space Economy



    Published in:

    Handbook of Space Resources ; Chapter : 32 ; 1053-1107


    Publication date :

    2023-04-28


    Size :

    55 pages




    Type of media :

    Article/Chapter (Book)


    Type of material :

    Electronic Resource


    Language :

    English





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