Accounting for Epistemic Uncertainty in Mission Supportability Assessment: A Necessary Step in Understanding Risk and Logistics Requirements

dc.creatorOwens, Andrew
dc.creatorde Weck, Olivier
dc.creatorStromgren, Chel
dc.creatorGoodliff, Kandyce
dc.creatorCirillo, William
dc.date.accessioned2017-07-06T18:38:44Z
dc.date.available2017-07-06T18:38:44Z
dc.date.issued2017-07-16
dc.descriptionAndrew Owens, Massachusetts Institute of Technology, USA
dc.descriptionOlivier de Weck, Massachusetts Institute of Technology (MIT), USA
dc.descriptionChel Stromgren, Binera, Inc., USA
dc.descriptionKandyce Goodliff, NASA Langley Research Center, USA
dc.descriptionWilliam Cirillo, NASA Langley Research Center, USA
dc.descriptionICES511: Reliability for Space Based Systems
dc.descriptionThe 47th International Conference on Environmental Systems was held in South Carolina, USA on 16 July 2017 through 20 July 2017
dc.description.abstractFuture crewed missions to Mars present a maintenance logistics challenge that is unprecedented in human spaceflight. Mission endurance – defined as the time between resupply opportunities – will be significantly longer than previous missions, and therefore logistics planning horizons are longer and the impact of uncertainty is magnified. Maintenance logistics forecasting typically assumes that component failure rates are deterministically known and uses them to represent aleatory uncertainty, or uncertainty that is inherent to the process being examined. However, failure rates cannot be directly measured; rather, they are estimated based on similarity to other components or statistical analysis of observed failures. As a result, epistemic uncertainty – that is, uncertainty in knowledge of the process – exists in failure rate estimates that must be accounted for. Analyses that neglect epistemic uncertainty tend to significantly underestimate risk. Epistemic uncertainty can be reduced via operational experience; for example, the International Space Station (ISS) failure rate estimates are refined using a Bayesian update process. However, design changes may re-introduce epistemic uncertainty. Thus, there is a tradeoff between changing a design to reduce failure rates and operating a fixed design to reduce uncertainty. This paper examines the impact of epistemic uncertainty on maintenance logistics requirements for future Mars missions, using data from the ISS Environmental Control and Life Support System (ECLS) as a baseline for a case study. Sensitivity analyses are performed to investigate the impact of variations in failure rate estimates and epistemic uncertainty on spares mass. The results of these analyses and their implications for future system design and mission planning are discussed.
dc.format.mimetypeapplication/eng
dc.identifier.otherICES_2017_109
dc.identifier.urihttp://hdl.handle.net/2346/72931
dc.language.isoeng
dc.publisher47th International Conference on Environmental Systems
dc.subjectSupportability
dc.subjectRisk
dc.subjectUncertainty
dc.subjectEpistemic
dc.subjectLogistics
dc.subjectReliability
dc.titleAccounting for Epistemic Uncertainty in Mission Supportability Assessment: A Necessary Step in Understanding Risk and Logistics Requirementsen_US
dc.typePresentations

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