1、Lessons Learned Entry: 0980Lesson Info:a71 Lesson Number: 0980a71 Lesson Date: 2000-06-12a71 Submitting Organization: GSFCa71 Submitted by: Kevin GradySubject: Spacecraft Interface Simulators Description of Driving Event: The Terra spacecraft relied on several state-of-the-art developments, as a res
2、ult of the demanding resource requirements of the Terra instrument suite. These spacecraft development activities were performed in parallel with five state-of-the-art remote sensing instrument developments. Due to the nature of this extensive development, it was anticipated that difficulties and sc
3、hedule challenges would arise on both sides of this interface. The challenge, which faced the Project, was how to mitigate the risk of verification of this interface, particularly when that flight interface might not be verified until very late in the systems integration schedule. The challenge was
4、compounded by the fact that two of the Terra instruments were international instruments.Lesson(s) Learned: The approach which the Project undertook was to develop simulators which electrically duplicated the spacecraft side of the interface. These simulators were then shipped to the instruments on a
5、 rotating basis. Tests were performed with instrument engineering model hardware and the flight instruments as well. These tests were performed on the flight instruments, after the flight instrument was assembled, but before the lengthy environmental and calibration test phases which complex instrum
6、ents demand. This gave the instrument developers the confidence that their instrument would be compatible with the spacecraft, when the time came to integrate into the spacecraft. In doing this, it avoided the possibility of having to make a significant instrument modification, as a result of an int
7、erface incompatibility, after the instrument had been delivered. This in turn could have resulted in the need for additional regression testing (T/V, EMI/EMC) and the attendant schedule impact.In addition to the benefits of isolating design or workmanship errors in the instruments spacecraft interfa
8、ce early, it provided an early opportunity for the instrument teams to work in the environment that they would be seeing, after they delivered their instrument to the spacecraft facility. Command Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-and te
9、lemetry databases were hosted on the spacecraft interface simulator, and building block procedures, which were to be executed later at spacecraft level, could be debugged at this early opportunity prior to instrument delivery. The planning and information interchange necessitated by the use of this
10、interface simulator hardware caused spacecraft and instrument teams to become cognizant of integration and test issues much sooner than they likely would have. This led to a Terra instrument integration activity which was virtually trouble free.The spacecraft interface simulators deployed during the
11、 instrument integration and test phases played an enormous role in the eventual ease of instrument integration. The Terra experience is a strong endorsement for the use of spacecraft simulators at the instrument developers facility during instrument integration and test. This is particularly true wh
12、en significant development risk resides on both sides of the interface and the complexity of the instruments is such that a significant amount of time is invested during the instrument environmental test flow.Recommendation(s): The spacecraft interface simulators deployed during the instrument integ
13、ration and test phases played an enormous role in the eventual ease of instrument integration. The Terra experience is a strong endorsement for the use of spacecraft simulators at the instrument developers facility during instrument integration and test. This is particularly true when significant de
14、velopment risk resides on both sides of the interface and the complexity of the instruments is such that a significant amount of time is invested during the instrument environmental test flow.Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71
15、 ScienceAdditional Key Phrase(s): a71 Ground Equipmenta71 Test & VerificationAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 2001-08-07a71 Approval Name: Jay Liebowitza71 Approval Organization: GSFCa71 Approval Phone Number: 301-286-4467Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
