Limitations of Reliability for Long-Endurance Human Spaceflight
Name
20160012010.pdf
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689.17 KB
Format
Adobe PDF
Checksum (MD5)
75d7fbf42cc0c7efb96bc4eb590e24f0
Author(s)
Owens, Andrew Charles
De Weck, Olivier L
Date Issued
September 2016
Journal
AIAA SPACE 2016
Publisher
American Institute of Aeronautics and Astronautics (AIAA)
Citation
Owens, Andrew, and Olivier De Weck. “Limitations of Reliability for Long-Endurance Human Spaceflight.” AIAA SPACE 2016 (September 9, 2016).
Version
Author's final manuscript
Abstract
Long-endurance human spaceflight - such as missions to Mars or its moons - will present a never-before-seen maintenance logistics challenge. Crews will be in space for longer and be farther way from Earth than ever before. Resupply and abort options will be heavily constrained, and will have timescales much longer than current and past experience. Spare parts and/or redundant systems will have to be included to reduce risk. However, the high cost of transportation means that this risk reduction must be achieved while also minimizing mass. The concept of increasing system and component reliability is commonly discussed as a means to reduce risk and mass by reducing the probability that components will fail during a mission. While increased reliability can reduce maintenance logistics mass requirements, the rate of mass reduction decreases over time. In addition, reliability growth requires increased test time and cost. This paper assesses trends in test time requirements, cost, and maintenance logistics mass savings as a function of increase in Mean Time Between Failures (MTBF) for some or all of the components in a system, based on a review of reliability growth models in literature and a quantitative case study. In general, reliability growth results in superlinear growth in test time requirements, exponential growth in cost, and sublinear benefits in terms of maintenance logistics mass saved. In the Mars transit case study examined here, doubling the reliability of all components results in a 24% reduction in corrective maintenance mass requirements. However, if only some components experience improved reliability the benefits are reduced; if only the ten largest contributors to corrective maintenance requirements experience doubled reliability, the decrease in mass is reduced to 9%. These trends indicate that it is unlikely that reliability growth alone will be a cost-effective approach to maintenance logistics mass reduction and risk mitigation for long-endurance missions. This paper discusses these trends as well as other options to reduce logistics mass such as direct reduction of part mass, commonality, or In-Space Manufacturing (ISM). Overall, it is likely that some combination of all available options - including reliability growth - will be required to reduce mass and mitigate risk for future deep space missions.
MIT Department
Massachusetts Institute of Technology. Department of Aeronautics and Astronautics
Massachusetts Institute of Technology. Engineering Systems Division
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Creative Commons Attribution-Noncommercial-Share Alike
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.2514/6.2016-5308
