Abstract. Tumblenauts are a swarm of minimalist, bacteria-inspired robots designed for collaborative inspection of pressurized microgravity habitats such as the International Space Station. Unlike current intra-vehicular robots that rely on complex, actuator-dense mechanisms for precise motion, the Tumblenauts use a stochastic run-and-tumble locomotion inspired by bacterial motility. This unique locomotion paradigm enables a simpler design, improves scalability, and greatly reduces actuation requirements, making the Tumblenauts among the smallest and least actuator-dense robots built for microgravity. In this paper, we present the design of the Tumblenaut, describe how it achieves run-and-tumble locomotion, and characterize its motion dynamics using Earth-based microgravity testbeds. Furthermore, using a data-driven simulation, we demonstrate how the Tumblenauts can perform a diverse set of inspection tasks by leveraging collective behavior.Specifically, we show that the swarm can collaboratively map environments, achieve directed navigation through a chemotaxis-inspired control mechanism, and make global inspection classification decisions by sharing information. As a new generation of space habitats is launched into orbit, we envision swarms o Tumblenauts run-and-tumbling within them, providing continuous monitoring and supporting the long-term sustainability of these stations.