Understanding Sustainability in the Human Exploration Campaign

With the resurgence of space exploration at the dawn of the 21st century, space agencies will be working together with their industry partners to establish systems and infrastructure that enable future lunar missions and develop capabilities for the exploration of Mars. The upcoming Artemis missions will return humans to the Moon with the first crewed landing since 1972. Unlike the Apollo era, the focus of humanity's return to the Moon includes the emplacement of a diverse set of new systems and long-term infrastructure that emphasize a sustained lunar presence and enable upcoming missions to Mars. As the Artemis missions to the lunar surface begin, one of the overarching goals is to establish systems and infrastructure that are sustainable. Consensus on accurately defining this term in the context of space exploration is still emerging, as there are no established standards, nor are there clear oversight bodies for their implementation. Open Systems Architecture (OSA) and Modular Open Systems Approach (MOSA) standards are used in various technology domains that facilitate sustainable systems, though they have not yet been actively adopted within human space exploration development. Sustainability in this context includes optimizations associated with industrial ecology, the study of material and energy flows through industrial systems, with a focus on conserving and reusing resources. Financial sustainability references the ability to execute a program within a realistic budget and with funding that is highly likely to be available. The advent of a commercial lunar economy will play a key role in this concept. Policy sustainability means the program supports the long-term interests of a governing body, broadly and consistently, over time. Sustainability also differs from the systems lifecycle term sustainment, largely in that the human exploration campaign operates as a system of systems. In another vantage, sustainability can be viewed as optimization to minimize the entropy of a system with respect to its defined execution goals. This paper will explore aspects of sustainable design and how they apply to the systems and technologies under development for Artemis missions. It will discuss a conceptual exploration architecture that builds capability over time for both lunar and Mars exploration, and it will highlight human exploration driven technological reach-back opportunities that can apply to terrestrial sustainability. It also will introduce the concept of tipping points; key system design implementations or technology introductions that enable disproportionate optimizations in maintenance, resource utilization, and/or operations. For example, tipping points can include when water/propellant can be sourced at lower cost from the Moon than from Earth or when non-terrestrial regolith can be processed in situ for additive manufacturing. Each exploration mission, crewed or robotic, provides the opportunity to build upon the previous mission to demonstrate technologies and operations that advance toward these tipping points. This paper will also show that sustainable infrastructure built on the Moon will enable the construction of infrastructure for crewed Mars missions, with discussion on architectural decisions that enable greater sustainability for human exploration of the Moon, Mars, and beyond.