1、Lessons Learned Entry: 0441Lesson Info:a71 Lesson Number: 0441a71 Lesson Date: 1996-08-23a71 Submitting Organization: JPLa71 Submitted by: J.W. BottSubject: Contamination of the Mars Observer Spacecraft by Environmental Conditioning (1992) Abstract: The exterior of MO was found to be dirty after the
2、 spacecraft had been mated to the launch vehicle. The air conditioning piping or the nitrogen purge system were the likely sources of the contamination. Similarly, deterioration of the nitrogen delivery system for Topex at a contractor facility produced heavily contaminated output. Use gas use suppl
3、ies only from known, proven sources, investigate the gas supply source and delivery system, and test gases at the source and at the point of delivery.Description of Driving Event: 1. When the Mars Observer (MO) spacecraft was installed on the launch vehicle at KSC, an air conditioning duct and a Nit
4、rogen purge system were installed at access points to the shroud over the MO spacecraft. Following activities associated with a hurricane, a payload cable inspection showed the spacecrafts external surfaces to be heavily contaminated with particulate matter. This led to delay of the launch, and remo
5、val of the spacecraft to the preparation facility for cleaning. The source of the contamination was never identified with certainty, but available evidence pointed to piping in the air conditioning system as the most probable source of the contamination, with the Nitrogen purge system also a possibl
6、e source. Following replacement of piping in the air conditioning system, a purge of both piping systems, and the addition of a Nitrogen filter, the problem did not re-occur.2. On the TOPEX project, a similar event was averted at a contractors facility, after a resident JPL QA representative request
7、ed a particle count on the output of a Nitrogen delivery system. The output was found to be heavily contaminated, which necessitated the use of a newly cleaned and tested purge cart. Although pure Nitrogen was manufactured on-site, the delivery system included passage through an aged distribution sy
8、stem, whose interior had deteriorated.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Reference(s): PFR #54717Lesson(s) Learned: 1. Air and Nitrogen supplies are often a source of particulate and/or fluid contaminants.2. Piping and other types of del
9、ivery systems may also be sources of contamination.3. JPLs past experience has shown that certifications on the purity of delivered Nitrogen supplies are not always reliable.4. JPLs past experience also has shown that although initially certified, Nitrogen at the point of usage can be contaminated.R
10、ecommendation(s): 1. Where chemically pure gas supplies are a requirement, use only supplies from known, proven sources, particularly sources for Nitrogen.2. Investigate and qualify delivery systems, as well as sources of gas supply.3. Test and qualify gases at the point of delivery to sensitive equ
11、ipment, as well as at the source.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 EnvironmentAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 1996-08-23a71 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-,-,-
