1、Lessons Learned Entry: 1514Lesson Info:a71 Lesson Number: 1514a71 Lesson Date: 2005-02-08a71 Submitting Organization: MSFCa71 Submitted by: William W. Vaughan, Ph.D.Subject: One Environmental Effect Can Greatly Complicate Solution of Another Abstract: For the Chandra thermal-plasma environments inte
2、ractions, the 1992 Program re-baseline removed two instruments, one of which required active thermal control. The orbit for Chandra was changed from LEO to high elliptical and the thermal control concept simplified to passive “cold biased“ surface plus heaters. This change in thermal control concept
3、 resulted in the mandating of silver Teflon thermal control surfaces.Description of Driving Event: The Teflon thermal control surfaces plus the high elliptical orbit resulted in severe spacecraft charging and electrostatic discharge environment, which necessitated an aggressive Electrostatic Dischar
4、ge (ESD) test and circuit protection effort at a cost of over one million dollars.Lesson(s) Learned: Design solutions for one environment effect can greatly complicate solution for change in design as result of Program re-baseline action. Be wary of orbit modifications relative to change in natural
5、environment effects on spacecraft and instruments.Recommendation(s): All orbit modifications for a Program should ensure that effect on the spacecraft and instruments by the change in natural environments are taken into account before a final decision is made. Evidence of Recurrence Control Effectiv
6、eness: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-N/ADocuments Related to Lesson: NASA-HDBK-1001Mission Directorate(s): a71 Exploration Systemsa71 Space Operationsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Accident Investigationa71 Co
7、nfiguration Managementa71 Environmenta71 Extra-Vehicular Activitya71 Flight Equipmenta71 Hardwarea71 Mishap Reportinga71 NASA Standardsa71 Parts Materials & Processesa71 Payloadsa71 Policy & Planninga71 Program and Project Managementa71 Risk Management/Assessmenta71 Safety & Mission Assurancea71 Spacecrafta71 Standarda71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 2005-04-14a71 Approval Name: Lisa Carra71 Approval Organization: MSFCa71 Approval Phone Number: 256-544-2544Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
