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GP-B Post-Flight Analysis—Final Report - Gravity Probe B - Stanford ...

GP-B Post-Flight Analysis—Final Report - Gravity Probe B - Stanford ...

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On the day of the launch, many of the Responsible Equipment Engineers had opened multiple RTworksdisplays, in order to best monitor their equipment. Early on launch day, so many displays were “sent” to otherworkstations that OASIS fell so far behind keeping up in real-time that it crashed. The impact was immediatelynoticed, and the work-around quickly determined— simply close displays. The team was alerted, and throughcontinuing training, this problem never recurred.A better distributed processing solution would have been to run OASIS on any workstation that needed OASISdisplays, and simply pipe the low-bandwidth-telemetry to those workstations (i.e. do not use the Xterminalprotocol, run multiple instances of OASIS instead).4.6 The Integrated Test Facility (ITF)The Integrated Test Facility (ITF) is composed of flight-equivalent electronics boxes, software, and hardwaresimulators which model the <strong>GP</strong>-B space vehicle. The Pods in the ITF are computers designed to run and operatethe vehicle ground support software. In early phases of program development, the ITF is used to 1) test flighthardware for proper operation prior to being installed on the spacecraft, 2) test hardware interfaces, 3) resolvehardware discrepancies, and 4) develop and test flight software. Later in the program, the ITF is used to run testscenarios to verify software and operations sequences. The ITF also provides a flight-like space vehiclesimulation for the operations team to use during mission rehearsals. During the on-orbit phase of the program,the ITF is used to test sequences prior to being run on the vehicle and troubleshoot flight anomalies. The ITFhas been an important <strong>GP</strong>-B resource to reduce program riskThe electronic boxes in the ITF are listed in Table 4-11 below. Each unit is categorized as a Engineering Unit(EU) or Functional Equivalent Unit (FEU). A photograph of the ITF hardware is shown in Figure 4-13.Table 4-11. ITF equipment listEQUIPMENTTYPECommand / Control Computer Assembly (CCCA)FEUCommand and Telemetry Unit (CTU)FEUAttitude Control Electronics (ACE) ----------Aft Experiment Control Unit (Aft ECU)FEUFwd Experiment Control Unit (Fwd ECU)FEUInterface Unit (IU)FEUGlobal Position System Receiver A (<strong>GP</strong>S “A”)EUGlobal Position System Receiver B (<strong>GP</strong>S “B”)EUAft Gyro Suspension System 1 (AFT GSS1)EUAft Gyro Suspension System 2 (AFT GSS2)EUAft Gyro Suspension System 3 (AFT GSS3)FEUAft Gyro Suspension System 4 (AFT GSS4)EUFwd Gyro Suspension System 1 (Fwd GSS1)EUFwd Gyro Suspension System 2 (Fwd GSS2)EUFwd Gyro Suspension System 3 (Fwd GSS3) ----------Fwd Gyro Suspension System 4 (Fwd GSS4) ----------Aft Squid Readout Electronics A (Aft SRE A)FEUAft Squid Readout Electronics B (Aft SRE B)EUFwd Squid Readout Electronics A (Fwd SRE A)FEU<strong>Gravity</strong> <strong>Probe</strong> B — <strong>Post</strong> <strong>Flight</strong> Analysis • Final <strong>Report</strong> March 2007 121

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