Task impairment: A novel approach for assessing impairment during exploration-class spaceflight missions

Long duration deep space exploration missions require an innovative assessment for medical impairment. Task Impairment is a novel, dynamic, and mission-appropriate impairment paradigm which will replace Functional Impairment, the metric used currently by the NASA Integrated Medical Model for probabilistic risk assessment on the International Space Station. To derive Task Impairment, the Human Exploration of Mars: Preliminary List of Crew Tasks was used as the source of likely exploration mission tasks. Tasks were divided into one or more human system task categories (e.g., cardiopulmonary, cognitive, etc.). Subject matter experts across five medical specialties then reviewed medical conditions from the Informing Mission Planning via Analysis of Complex Tradespaces condition list to determine which of the 18 human system task categories were impaired in best and worst-case scenarios for treated and untreated variants of each condition. If a human system task category was determined to be affected by a condition, every task assigned to that category was presumed to be, at least partially, impaired. The resulting total tasks impaired by each medical condition were used to calculate Task Impairment values. As a direct assessment of a crewmember's ability to perform mission specific tasks, Task Impairment has the capacity to yield a higher fidelity measure of reduced crew ability than previous techniques. This technique is easily adapted to future proposed design reference missions and may be useful in defining mission phase-specific disability as well as a future medical loss of mission objectives metric.