1、Lessons Learned Entry: 0356Lesson Info:a71 Lesson Number: 0356a71 Lesson Date: 1994-12-13a71 Submitting Organization: JPLa71 Submitted by: D.D. LordSubject: Loss of Spacecraft due to Shroud Failure During Launch Abstract: A failure shortly after launch in the honeycomb shroud (nose cone) structure,
2、due to a lack of proper venting, caused Mariner 64 mission failure. Analyze the pressure profiles that the honeycomb structure will be exposed to, and assure adequate venting under worst case environment conditions.Description of Driving Event: Within minutes after the launch of the first Mariner 64
3、 spacecraft to Mars, it was determined that there were mechanical problems with the deployment of the solar panels and other appendages. The spacecraft eventually went dead from loss of electrical power when the battery power was depleted.Analysis of the incident indicated a failure in the honeycomb
4、 shroud (nose cone) structure due to a lack of proper venting. Internal pressures in the honeycomb structure itself, built up during the rapid change of ambient pressure during launch, combined with high shroud temperatures due to frictional forces in the near earth atmosphere, caused the shroud to
5、break up. It was established that the shroud contractor had not performed a combined thermal vacuum test that represented the launch profile conditions.Additional Keyword(s): Materials, OutgassingLesson(s) Learned: Internal pressures within honeycomb structures, in adverse environmental conditions,
6、can build to a point sufficient to cause break up of spacecraft components.Recommendation(s): Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Whenever honeycomb structures are used an analysis should be conducted of the temperature and ambient pressu
7、re profiles that the honeycomb structure will be exposed to during all phases of pre-launch and post-launch activities. It should then be verified to ensure that the honeycomb structure design provides for adequate venting or is structurally capable of withstanding the expected temperature and ambie
8、nt pressure profiles. The design of the honeycomb structure is verified by conducting a thermal vacuum test that accurately simulates the worst case environment that it will be exposed to during all phases of pre-launch and post-launch activities. The actual pressure vs. time profile that will occur
9、 during the worst case environment conditions should be used during this test.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Environmenta71 Parts Materials & Processesa71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1987-03-26a71 Approval Name: Carol Dumaina71 Approval Organization: 125-204a71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
