Characterizing Self-Sufficiency and Habitability for Autonomous Deep-Space Habitat Operations

Zaccarine, Sophia Anne

Graduate Thesis Or Dissertation

Characterizing Self-Sufficiency and Habitability for Autonomous Deep-Space Habitat Operations Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/s7526f276

Abstract

Deep-space human exploration will necessitate increasing operational autonomy for the crew and habitat as reliance on extensive Earth support becomes impractical. In this context, the habitat and onboard crew must effectively become an ‘autonomous system’ that can operate for finite periods without external intervention from outside a defined control volume, which historically has extended beyond the habitat to include ground facilities, teleoperators, and other space assets. For deep-space exploration missions, however, timely logistical resupply becomes impractical and communication with Earth is delayed, or even impossible at times from occultations. Therefore, to enable the operational autonomy needed to accomplish the overall mission objectives, additional onboard capabilities will be required to offset decreased Earth-based support and move toward self- sufficiency. These capabilities may be facilitated by emerging technologies, This thesis characterizes the required functionality needed to enable operational autonomy in deep-space and identifies other potential benefits, or improvements beyond State of the Art (SoA), that can be provided by design attributes for emerging technologies to close the gap between current Earth-dependent limitations and required (or desired) onboard capabilities.

First, the general functionality needed to enable deep-space missions is identified and categorized as nominal, off-nominal, or a blend between the two with the goal of enabling operational autonomy. These primary enabling capabilities are further broken down into operations that involve monitoring, maintenance and fault management. This dissertation identifies and examines these basic requisite capabilities using an abstraction hierarchy process to create a visual representation of a functional decomposition, along with an information flow model as components of a work domain analysis. The effort is aimed at establishing design considerations for enabling self-sufficient deep-space autonomy, referred to as Earth Independent Systems Operations (EISO).

Second, other non-essential, but potentially beneficial, opportunities are explored for their contributions to improving habitability. Where self-sufficiency captures required functionality, potentially beneficial opportunities that can improve crew well-being can be mapped to habitability. This research proposes a process to characterize habitability by aligning it with two of the three key tenets of a human-rated spacecraft: Accommodate and Utilize, while the third tenet, Protect, which is focused on risk mitigation, is not addressed in this research effort. Novel stratifications of ‘Attributes of Accommodate’ (what the habitat does) and ‘Degrees of Utilize’ (what the crew does) to assess the tenets of accommodate and utilize are proposed to detail how a habitat with increasingly autonomous capabilities influences habitat and crew task allocation. Components of habitability, distilled from a broad literature review, are then aligned with proposed attributes of accommodate and applied to select examples from past missions.

Third, a triangulation method is incorporated that uses a combination of qualitative and quantitative research methods. This approach supplements the top-down functional analysis with a bottom-up, empirically derived set of data that demonstrates the utility of the work compiled from the characterization of self-sufficiency and habitability. Qualitative interviews with subject matter experts (SMEs) were conducted under CU IRB Protocol #23-0669 to identify design attributes that are deemed to be important when designing toward a maintainable ECLSS. The interview goals were derived from the broader topics of self-sufficiency and habitability to focus on ‘maintenance’ as an example representing one category of the general enabling capabilities needed for deep-space autonomy. These attributes are compiled into Design Considerations and Operational Considerations and were derived using thematic analysis.

Finally, to further contextualize the attributes of maintainable ECLSS and better understand how to use them in future trade studies when designing deep-space habitats, a Likert rank-order survey was created and distributed to ECLSS professionals with a request to rank the compiled attributes as ‘Not Important’, ‘Somewhat Important’, ‘Important’, or ‘Very Important,’ with an option to select ‘Unsure’ for no ranking. To assess validity of the listed design attributes, these participants were also asked to contribute any additional themes they thought were missing from the analysis. The results are displayed in a diverging stacked bar chart which demonstrates the relative importance of the ranked attributes. From the survey, two additional design attributes were provided in the free-response questions, one of which was added to the overarching drivers, which resulted in a total of 24 attributes ranked for consideration when designing maintainable ECLSS. The set of 24 attributes are compared to several NASA design standards and handbooks to assess their alignment with broader topic of maintainability. Given that ECLSS is a critical subsystem tasked with keeping the crew alive, many of the derived design attributes are also extensible to a number of other critical subsystems on a deep-space habitat.

These results propose a systematic method for identifying the functionality required to enable operationally autonomous deep-space missions by characterizing self-sufficiency and/or improving habitability as underlying design drivers. The process presented demonstrates a combination of top-down functional analysis methods with bottom-up qualitative and quantitative experimental data.

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