1、Lessons Learned Entry: 1615Lesson Info:a71 Lesson Number: 1615a71 Lesson Date: 2005-08-29a71 Submitting Organization: ARCa71 Authored by: Donald R. MendozaSubject: Risk Management: Cascading and Worst Case Events Abstract: Cascading and/or multiple failures must be considered during risk assessments
2、 to ensure hazard controls are adequate should they be required to address more than one failure at a time. Description of Driving Event: STS 90/Neurolab was a Spacelab module mission focusing on the effects of microgravity on the nervous system. The mission was flown abroad the Columbia and launche
3、d on the 17 of April 1998 and lasted 17 days. The goals of Neurolab were to study basic research questions and to increase the understanding of the mechanisms responsible for neurological and behavioral changes in space. The mission was a joint venture of several space agencies and U.S. research age
4、ncies including the National Institutes of Health, the National Science Foundation, and the Office of Naval Research, as well as the space agencies of Canada, France, Germany, and Japan, and the European Space Agency. While the Neurolab mission was an overall success it experienced several on-orbit
5、animal habitat hardware failures and problems. In addition, the missions approach to problem resolution of this type depended heavily on crew intervention. This approach proved to be unrealistic given the complicated nature of the mission since the crews time was already limited. Lesson(s) Learned:
6、Not having a formal and integrated risk management plan (RMP) will mask system wide risk and/or the total risk resulting from the accumulation of several “acceptable” risks. Thus, “minor” risks associated with a specific piece of hardware may be accepted at inappropriate management levels without re
7、gard to the overall mission risk, resulting in an unnecessary increase in overall risk with a corresponding decrease in mission success probability. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- While expected risk values associated with individua
8、l components may be acceptable, their aggregated and worst case scenarios should also be considered since if all goes bad (cascading or multiple failures) the crew or any other control mechanism will not be able to respond adequately. Recommendation(s): All missions must incorporate a systematic and
9、 formal RMP into their management plan that is compatible with the process identified in NPR 7120.5 (identify, analyze, plan, track, control and communicate risks) in terms of managing risks. Specific attention should be given to how risks associated with individual pieces of hardware/software are a
10、ggregated with risks of other sub-systems to reflect total mission risk. Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: NPR 7120.5Mission Directorate(s): a71 Exploration Systemsa71 Sciencea71 Aeronautics Researcha71 Space OperationsAdditional Key Phrase(s): a71 Program
11、 and Project Managementa71 Risk Management/Assessmenta71 Safety & Mission AssuranceAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 2006-04-17a71 Approval Name: dkruhma71 Approval Organization: HQProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
