Designing for Usability in Modular Space Habitats: A Space Syntax Perspective

As human ambitions turn toward establishing settlements on the Moon and Mars, the architectural and spatial configuration of these habitats has received comparatively little attention relative to their engineering systems. This paper explores the spatial configuration and architectural usability of modular extraterrestrial settlements, focusing on their potential growth, vulnerability, and navigability. Drawing from architectural theory and Space Syntax methods, we propose a novel framework for evaluating habitat layouts based on two key metrics: intelligibility and vulnerability. Using a combination of analytic tools and simulations — including adapted versions of the 'beady-ring' growth model — we assess both small-scale configurations and larger aggregated settlements. We introduce a new vulnerability metric based on spatial types and configurational redundancy, allowing us to quantify how module failure can fragment a habitat system. Our findings confirm five core hypotheses, including the inverse relationship between structural resilience and spatial intelligibility as modular settlements scale, and the applicability of Space Syntax theories to non-terrestrial environments. We argue that without deliberate planning, accretive modular growth leads to declining usability, and we advocate for intentional and informed planning interventions, to sustain human-centered design at larger scales. This work provides a foundational methodology for evaluating and guiding the spatial evolution of off-world settlements.