1、Lessons Learned Entry: 0432Lesson Info:a71 Lesson Number: 0432a71 Lesson Date: 1996-07-17a71 Submitting Organization: JPLa71 Submitted by: A.G. GussnerSubject: Mars Observer (MO) TWTAs Were Not Qualified (while powered) for Pyrotechnic Shock (1993) Abstract: The MO Traveling Wave Tube Amplifiers (TW
2、TAs) were not powered during qualification Pyrotechnic Shock testing. As a result, the TWTA beam and cathode heaters were not powered during the critical MO tank pressurization to allow real time telemetry during this critical event. Fully consider the cost/risk tradeoff of not qualifying critical i
3、nherited designs for new operational uses.Description of Driving Event: The MO Traveling Wave Tube Amplifiers (TWTAs) were not powered during qualification Pyrotechnic Shock testing. As a result, the contractors operations plan included not powering the beam and cathode heaters of both redundant TWT
4、As (thus no downlink telemetry) during the critical MO tank pressurization. Although this was a topic of significant debate during the design and manufacturing phases, early cost constraints resulted in decisions not to perform developmental testing and analysis to show whether or not there would be
5、 a problem powering the TWTA during the MO Pyrotechnic events. Analysis was performed to determine the lateral and axial capability of the cathode support design when powered off (cold). Actual testing to qualify the TWTA for powered operation (hot) was not performed, also based on programmatic cost
6、 constraint decisions.Additional Keyword(s): RF TestingReference(s):“MO Design & Implementation Audit“: JPL D-11433“MO Loss of Signal: Special Review Board Final Report“: JPL Publication 93-28“Report of the MO Mission Failure Investigation Board“ (the Coffey Report)Provided by IHSNot for ResaleNo re
7、production or networking permitted without license from IHS-,-,-Lesson(s) Learned: Unless precluded by solar system obstacles, a spacecraft should be configured to allow real time telemetry during critical events. Such telemetry may provide crucial spacecraft health and safety data for other spacecr
8、aft missions with similar systems or activities as well as for the current mission.Recommendation(s): Fully consider the cost/risk tradeoff of not qualifying critical inherited designs for new operational uses.Potential loss of function of a redundant element may be preferable to obtaining no teleme
9、try during high risk events.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Communication Systemsa71 Hardwarea71 Test & VerificationAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 1995-09-14a71 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-,-,-
