1、Lessons Learned Entry: 0352Lesson Info:a71 Lesson Number: 0352a71 Lesson Date: 1994-12-08a71 Submitting Organization: JPLa71 Submitted by: R.F. Miles, Jr.Subject: Contamination Control for Susceptible Instruments Abstract: During thermal-vacuum testing of Wide-Field/Planetary Camera, the sensitivity
2、 of the charge coupled device detectors decreased due to contamination. It was concluded that the standard criteria for the selection of organic and inorganic materials and associated processes with respect to outgassing are not acceptable with a new class of instruments. Each project with contamina
3、tion-susceptible instruments should specify design criteria and should use decontamination procedures consistent with instrument-sensitivity objectives and project resources.Description of Driving Event: During thermal-vacuum testing of Wide-Field/Planetary Camera (WF/PC-1), the sensitivity of the c
4、harge coupled device detectors decreased due to contamination. It was subsequently determined that the source of the contamination was in the instrument, and not in the test equipment.Standard criteria have been used on JPL flight hardware for the selection of materials and processes, for which the
5、selection of outgassing characteristics were of prime consideration. The criteria have required that organic materials have a total mass loss of less than one percent and a collected volatile condensable mass of less than 0.1 percent when tested in accordance with ASTM method E595-77.These standard
6、criteria are no longer adequate and have resulted in the reduction of the useful wavelength ranges of instruments such as WF/PC. These instruments have orders of magnitude increases in susceptibility to contamination because of the low temperatures at which the optics and sensors operate. The standa
7、rd techniques of boiling off the contamination with flash heating has not proven to be effective, either because the time constant for return of the contamination is too short (minutes to hours) or because polymerization causes the contamination to be permanently adhered.Provided by IHSNot for Resal
8、eNo reproduction or networking permitted without license from IHS-,-,-Reference(s): PFR # 53912.Lesson(s) Learned: The standard criteria for the selection of organic and inorganic materials and associated processes with respect to outgassing are not acceptable with a new class of instruments - those
9、 having susceptible optics and sensors operating at cold temperatures.Recommendation(s): 1. A task should be undertaken to understand the limits to which spacecraft and instrument contamination can be reduced for various levels of funding, and to develop design criteria and decontamination procedure
10、s to achieve these limits.2. Each project, for each contamination-susceptible instrument, should specify instrument-sensitivity objectives achievable with project resources.3. Each project with contamination-susceptible instruments should specify design criteria and should use decontamination proced
11、ures consistent with instrument-sensitivity objectives and project resources.4. A task is presently being funded by the WF/PC project to characterize the contamination sources for WF/PC-II. Carry this task through to completion and make the data available for future projects.Evidence of Recurrence C
12、ontrol Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Environmenta71 Spacecrafta71 StandardAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 1990-06-21a71 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-,-,-
