1、Lessons Learned Entry: 0346Lesson Info:a71 Lesson Number: 0346a71 Lesson Date: 1994-10-21a71 Submitting Organization: JPLa71 Submitted by: Marilyn PlattSubject: Use of Heritage Designs on the Mars Observer Abstract: Although inherited designs were to be used extensively, many Mars Observer spacecraf
2、t subsystems were so extensively modified over the 8-plus year development period that their heritage was lost. Perform inheritance reviews to span differences in design usages, ensure inheritance reviews include the assessments listed in the lesson, and perform delta reviews when major mission chan
3、ges occur.Description of Driving Event: As originally envisioned, inherited designs were to be used for many of the Mars Observer spacecrafts engineering subsystems. During its eight-plus year development period, however, the Mars Observer mission underwent a number of significant changes. Many of t
4、he spacecraft subsystems were so extensively modified for Mars Observer that their heritage was lost.Other subsystems, whose heritage remained intact but which were designed for an earth-orbital environment, were not requalified to verify that they would function properly on an interplanetary missio
5、n of three years duration. Examples include:1. The failure to fully qualify the Traveling Wave Tubes (TWT) in the transmitter power amplifiers for operation during pyro-shock events.2. The lack of robustness in the design of the bipropellant pressurization system for long duration missions.3. The us
6、e of fault-management software, containing processing algorithms derived from the Defense Meteorological Satellite Program (DMSP), that was not fully understood.Reference(s):Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1. Mars Observer Loss of Sig
7、nal: Special Review Board Final Report: JPL Pub. 93-282. JPL Lesson Learned, No. 3-108, Subject: Mars Observer Pressure Modulator Infrared Radiometer (PMIRR) Cooler Failure During Vibration Testing3. JPL Lesson Learned, No. 10-102, Subject: Mars Observer Inertial Reference Loss4. IOM 525-89-344, dat
8、ed 12/14/89, by L. E. Baughman and R. F. Draper, Subject: MMII Inheritance ReviewsLesson(s) Learned: Reliance on heritage hardware/software in spacecraft design, without a thorough analysis of compatibility with mission requirements and required changes, can result in the use of design and component
9、s which are inappropriate for the mission.Recommendation(s): 1. Perform inheritance reviews to span the differences between the previous use of existing spacecraft designs, hardware and software, and planned new usage.2. Inheritance reviews should include the following assessments: a. Verification t
10、hat the inherited hardware/software designs are compatible with the spacecraft design, mission environment, qualification requirements and product assurance requirements.b. Verification of the necessity and mission compatibility of design changes and implementation plans.c. Determination of whether
11、additional protoflight testing will be required for the inherited hardware/software.d. Identification of potential risks associated with documented problems of inherited hardware and software.3. Delta inheritance reviews should be performed when major mission changes occur.Evidence of Recurrence Con
12、trol Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Sciencea71 Space OperationsProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a71 Aeronautics ResearchAdditional Key Phrase(s): a71 SpacecraftAdditional Info: Approval Info: a71 Approval Date: 1994-10-20a71 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-,-,-
