The NASA human system risk mitigation process for space exploration

摘要

This paper describes NASA's innovative approach to assess and mitigate astronaut health and performance risks for space exploration missions beyond Low-Earth Orbit, with Mars as the focal destination. As human space missions gradually become more autonomous and complex to reach the Mars goal, the original risk management methodology falls short of providing accurate risk evaluations for the development of the corresponding countermeasures. A more systematic and refined approach is required to manage all the risks related to in-mission astronaut health and productivity, as well as the long-term effects on terrestrial quality of life after landing. Another important aspect of this new method is the ability to stratify all the human system risks relative to each other so effective tradeoffs can be made resulting in an optimized set of medical and performance competencies for future space mission architectures. The management of these risks at the portfolio level is based on several factors, not just Likelihood versus Consequence (LxC) scoring and its corresponding color: Red, Yellow, or Green. First, the resultant LxC score for each mission should include the respective level of uncertainty in the scoring. This uncertainty is determined by the evidence source, which ranges from cellular terrestrial to human inflight, the evidence type ranging from case study to causation, and the number of studies yielding similar results. Second, the risk characterization or "risk state of knowledge" should include the effectiveness level of current countermeasures to determine the need for further mitigation strategies. Third, the cost versus benefit evaluation of additional mitigation should be stacked against specific mission schedules; this will determine if the pending product development timelines meet mission deadlines. There is no immediate benefit in investing in technology development if the products will not be ready for the intended mission. Lastly, the subject matter experts and risk decision makers should review all the components of the previous evidence and debate in a formal setting the most sensible path forward to manage these risks, as every decision is important and unique. The decision process, with all pertinent parties involved, should provide insight into the possible negative effects of implementing a particular countermeasure on other human system risks; thus, the implementation of a particular mitigation should not increase the overall risk posture of the entire portfolio. The following content describes this methodology and its impact to assessing NASA's missions.