Control Effectiveness: The Probability of Availability

In the unforgiving environment of space, astronauts must be prepared to handle any disruption, foreseen or unforeseen, that threatens the safety and integrity of their habitat. From micrometeorite impacts to moonquakes, these disruptions can lead to catastrophic consequences if not addressed quickly. The challenge lies in ensuring that the necessary repair strategies are available when needed—without exceeding the limited area in the spacecraft. This thesis focuses on the concept of the probability of availability, an important parameter that helps mission planners determine how much inventory of safety controls should be packed for long duration space missions. Using probability models, we explore how different probabilities of disruptions and multiple repair strategies can affect the availability of repair tools and supplies. We have developed a model that identifies the initial inventory of implementation strategies required to mitigate various hazards. Our findings reveal that balancing crew safety with inventory constraints is not straightforward. Packing too few repair materials, even with a low probability of disruptions, could lead to disastrous outcomes. Conversely, overpacking wastes cargo space. This research demonstrates how the probability of availability model allows mission planners to make data-driven decisions that ensure a crew’s safety while taking cost and weight limits into consideration. The probability models for the inventory management of implementation strategies can be applied to other industries where inventory management is crucial. We emphasize how careful planning of the initial inventory, informed by probability models, could mean the difference between life and death in extreme environments.