1、Lessons Learned Entry: 0421Lesson Info:a71 Lesson Number: 0421a71 Lesson Date: 1996-07-08a71 Submitting Organization: JPLa71 Submitted by: J.A. RobertsSubject: Voyager II Instrument Boom Deployment Anomaly (1977) Abstract: The Voyager II Science Boom failed to indicate, by microswitch, that it had d
2、eployed completely. The design of deployment mechanisms should consider susceptibility to jamming by foreign objects. Deployment clearance verification testing should be repeated if any related changes are incorporated.Description of Driving Event: (Relevant Historical Lesson(s) Learned)On August 21
3、 1977, the Voyager II Science Boom failed to indicate, by microswitch, that it had deployed completely. Analysis of the spacecraft dynamics during jettison of the expended Solid Rocket Motor (SRM) case indicated that the science boom folding strut was not locked and that the boom momentarily refold
4、ed due to impulse from the SRM case separation. Subsequent star mapping using the scan platform-mounted TV cameras ascertained that the boom was within a tenth of a degree of the fully deployed position.Exhaustive tests were conducted to assess candidate causes. The possibilities investigated includ
5、ed equipment interferences, jamming by foreign matter, and excessive friction or binding due to low temperature phenomena. Some discrepancies were discovered, but a specific probable cause could not be identified.Additional contributing factors may have resulted from late incorporation of a number o
6、f cabling, thermal blanket, and external surface configuration changes.Reference(s): JPL Problem Failure Report (PFR) 41010/NASA Experience Bulletin No. 14Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Lesson(s) Learned: Ideally, deployment verifica
7、tion procedures should be performed on a completely assembled spacecraft subsequent to its final buildup. Mocked-up areas of critical clearance may be used, but their use introduces some risk.Recommendation(s): Avoidance of susceptibility to jamming by foreign objects should be a specific considerat
8、ion in design of deployment mechanisms.Deployment clearance verification testing should be repeated if any related changes are incorporated.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Hardwarea71 Spacecrafta71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1996-03-21a71 Approval Name: Carol Dumaina71 Approval Organization: JPLa71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
