1、Lessons Learned Entry: 1709Lesson Info:a71 Lesson Number: 1709a71 Lesson Date: 2005-11-15a71 Submitting Organization: MSFCa71 Submitted by: Lisa Carra71 POC Name: Marc Osbornea71 POC Email: marc.osbornenasa.gova71 POC Phone: (256) 544-2300Subject: CHANDRA Flight Note 439: Possible Micrometeriod Impa
2、ct (MMI) With Spacecraft Abstract: Detailed analysis of spacecraft telemetry shows that Chandra was likely impacted by a micrometeoroid on 15 November 2003. Analysis of subsystem telemetry showed no ill effects on the primary units. A thorough analysis of the impact area showed that all critical spa
3、cecraft units were protected from micrometeoroid impacts or were not in the possible impact region. A search for previous impact type events did return one other such event. This second event was smaller than the event of 2003:319 and is at the limit of our detection capabilities. Like the impact of
4、 2003:319, Chandra appears to have suffered no ill effects due to this second detected potential impact. Description of Driving Event: In Novermber, 2003, routine checks of the Spacecraft Engineering Daily Plots showed a disturbance in the pointing stability just before 16:00 UT on 2003:319 (Figure
5、1). Detailed analysis of spacecraft telemetry showed that Chandra was likely impacted by a micrometeoroid. The investigation ruled out all internal causes. The disturbance occurred during the yearly Leonid meteoroid shower. Since analysis ruled out a cause internal to the spacecraft for the disturba
6、nce, it was hypothesized that the spacecraft was struck by a Leonid or other micrometeoroid.Lesson(s) Learned: For additional information, see attached CHANDRA Flight Note 439 which details the analysis/investigation that led to these lessons. This analysis approach may be useful to other teams who
7、are Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-assessing potential micrometeriod impacts. Summary of lessons: - Some MMI occur at/near detection thresholds - MMI may show up as minor disturbances in flight data - Causes internal to the spacecraf
8、t must be ruled out to “prove“ the case for MMI - When MMI occurs, all major subsystems should be checked out extensively to verify a return to nominal performance Recommendation(s): Designers of similar spacecraft should take precautions to protect all critical subsystems from potential MMI, as the
9、se events do occur. When MMI occurs, all major subsystems should be checked out extensively to verify a return to nominal performanceEvidence of Recurrence Control Effectiveness: Analysis of subsystem telemetry has shown no long-term effects.Documents Related to Lesson: Click here to download docume
10、nt. Mission Directorate(s): a71 Space Operationsa71 ScienceAdditional Key Phrase(s): a71 Program Management.a71 Missions and Systems Requirements Definition.a71 Missions and Systems Requirements Definition.Mission concepts and life-cycle planninga71 Systems Engineering and Analysis.a71 Systems Engin
11、eering and Analysis.Long term sustainability and maintenance planninga71 Engineering Design (Phase C/D).a71 Engineering Design (Phase C/D).Crew Survival Systemsa71 Engineering Design (Phase C/D).Environmental Control and Life Support Systemsa71 Engineering Design (Phase C/D).Orbiting Vehiclesa71 Eng
12、ineering Design (Phase C/D).Spacecraft and Spacecraft Instrumentsa71 Safety and Mission Assurance.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a71 Safety and Mission Assurance.Early requirements and standards definitiona71 Safety and Mission Assur
13、ance.Maintenancea71 Safety and Mission Assurance.Product Assurancea71 Safety and Mission Assurance.Reliabilitya71 Program Management: Risk ManagementAdditional Info: a71 Project: CHANDRAApproval Info: a71 Approval Date: 2006-03-15a71 Approval Name: dkruhma71 Approval Organization: HQProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
