REG NASA-LLIS-0363--1994 Lessons Learned - Spacecraft Receiver Degradation at Launch Site.pdf

1、Lessons Learned Entry: 0363Lesson Info:a71 Lesson Number: 0363a71 Lesson Date: 1994-12-22a71 Submitting Organization: JPLa71 Submitted by: Jim TaylorSubject: Spacecraft Receiver Degradation at Launch Site Abstract: Four days before scheduled launch, routine tests on both Viking Orbiter receivers sho

2、wed degraded performance. These results were believed to have been influenced by the test environment. When designing system and subsystem tests one should carefully consider the environment and its possible effects on the test results.Description of Driving Event: Four days before scheduled launch,

3、 both Viking Orbiter receivers exhibited degraded thresholds during a routine precount test on the launch pad. This degradation would directly affect the ability of the Viking Orbiter to receive commands. Subsequent on-pad tests did not convincingly isolate the cause of the noise. Either the launch

4、RF environment or the spacecraft hardware could be the cause of the problem. The decision was made to replace all the microwave components between the radio assembly and the high gain antenna, thus delaying the launch five days. No receiver degradation occurred during the mission. Subsequent tests o

5、n the removed microwave hardware and dual-frequency rotary joints showed a possible noisy connector, though not to the degree of severity experienced on the pad.Additional Keyword(s): Launch OperationsLesson(s) Learned: Environments can significantly influence hardware testing, resulting in degraded

6、 performance.Recommendation(s): Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-When designing system and subsystem tests one should carefully consider the environment and its possible effects on the test results. Those environments most likely to in

7、fluence test results are temperature; electro-magnetic radiation; radio-frequency radiation, reflection and interactions; gravity; and humidity. Care should also be taken to test all components and assemblies prior to the system test so as to detect and correct all performance degradations.Evidence

8、of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): a71 Environmenta71 Test & VerificationAdditional Info: Approval Info: a71 Approval Date: 1985-12-19a71 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-,-,-