GLAST Large Area Telescope: I & T Peer Review I&T Test Plans Brian Grist SU-SLAC Subsystem Engineer bgrist@slac.

1. Gamma-ray Large Area Space Telescope GLAST Large Area Telescope: I & T Peer Review I&T Test Plans Brian Grist SU-SLAC Subsystem Engineer bgrist@slac.stanford.edu 650-926-2998

2. Outline • Test flow • Plan Overview • Readiness Reviews • Test Plans (Sequence, Plan Flow, Requirements-From Mechanical Systems, Facilities) • Comprehensive/Limited Performance • Redundancy Verification • Survey • Mass Properties • Modal • EMI/EMC • Sine Vibration • Acoustic • TBAL/TVAC • Airplane Test (TBR)

3. Integration and Test Flow

4. Test Plan Directive

5. Reviews • Test Readiness Review- LAT-MD-00408 LAT Instrument Performance Verification Plan • A test readiness review will be conducted prior to commencing a flight level test program as required in the Systems Engineering Management plan, LAT-MD-00066. This review will be imposed upon all subsystem and system level qualification and flight level test programs. Topics to be addressed at the review are: • Changes since CDR • Test Requirements • Planned tests • Test Entry / Exit Criteria • Test facilities • Equipment calibration • Test configurations • Test procedure status • Staffing plans • System performance review • Quality program review • Problem / failure reports • Risk assessment • System safety • Test schedule • Issues and concerns

6. Comprehensive and Limited Performance Tests • The system level Performance tests requirements flow from the subsystems and system engineering. • The Integration and Test plan to implement the Electrical Performance test is LAT-MD-01055. Integration and Test Flow Test Plan Flow

7. Comprehensive and Limited Performance Tests • Comprehensive and Limited Performance Tests- LAT-MD-00408 LAT Instrument Performance Verification Plan • Comprehensive performance tests will be developed for use in support of LAT testing. LAT CPT testing will demonstrate the operation of all primary and redundant circuitry and paths for all operational modes. • Parameters will be varied over their specification ranges to insure that the unit performs as designed. • These tests will be performed to provide baseline data for each level of assembly. • A CPT will also be conducted during the hot and cold extremes of the temperature test or the thermal-vacuum test and at the conclusion of the environmental test sequence as well as at other times as needed in the verification procedures. • The LAT CPT will demonstrate that the hardware and software meet their performance requirements. • The CPT will also demonstrate that the instrument produces the expected responses. At lower levels of assembly, the test will demonstrate that, when provided with appropriate inputs, internal performance is satisfactory and outputs are within acceptable limits. • Limited Performance tests will be a subset of the CPT and will be performed before during and after environmental tests as appropriate

8. Test Name Type Power S/C Interface Test Point LPT LAT Initialization Power-Up/Boot    1553 Bus Interface 1553 Bus    SC Command Interface LAT Commanding    Housekeeping Data Telemetry    Science Data Collection Telemetry   GPS Time and GRB Alert Timing   CPU-to-CPU Communication FSW Internal     Configuration and Read back FSW Internal     LAT Environmental Sensors FSW Internal     Front End Strobe FSW Internal     Front End Charge Scan FSW Internal    TKR Cosmic Ray Trigger I&T    CAL Cosmic Ray Trigger I&T    ACD Cosmic Ray Trigger I&T    High Rate Trigger I&T    Event Filtering FSW Internal    LAT Pointing Calculation FSW Internal   Pointing Request Handling SC Commanding   Mode Operations LAT Commanding   Diagnostics and Calibration FSW Internal    Thermal Control System Thermal Control   Comprehensive and Limited Performance Tests Source: LAT Electrical Performance Test Plan (LAT-MD-01055) Draft

9. Redundancy Testing • A sequence of online “schema” (configurations) will be defined which mask out individual or combinations of Front Ends, Readout Controllers, Cable Controllers, TEMs. • The tests will consist of looping through the schema and taking test data to validate the redundant electrical paths. • LAT Electrical Performance Test Plan (LAT-MD-01055) details the redundant path testing.

10. Survey Plan • The system level survey requirements are defined in LAT-TD-00895. • The Integration and Test plan to implement the survey program is LAT-MD-01586. Integration and Test Flow w/ surveys in red Test Plan Flow w/ survey plans highlighted

11. Survey Test Organization • Survey program goals - LAT-TD-00895, LAT Survey Plan • Verify as-integrated interface stay-clears • Verify LAT alignment requirements • Verify science performance requirements • Validate analytical thermal-mechanical analysis models • Develop correlation functions for thermal-mechanical distortion • Predict the expected on-orbit precision of the instrument Source: LAT-MD-01586 LAT Survey and Alignment Plan

12. Survey Tests >3 Cosmic Ray test for continual monitoring. LAT Optical and Muon Surveys During Integration and Test Source: LAT-MD-00895 “LAT Instrument Survey Plan”

13. Equipment/Tool Quantity/Unit Supplier Laser tracker 1 portable unit SLAC Metrology Dept., Alignment Engineering Group 1-1/2” sphere mounted reflectors 66 reflectors w/ bushings SLAC Metrology Dept., Alignment Engineering Group ¾” sphere mounted reflectors 18 reflectors w/ bushings SLAC Metrology Dept., Alignment Engineering Group = reflector = laser tracker Surveyor 2 workers x 11 times x 4 hrs SLAC Metrology Dept., Alignment Engineering Group Tracker top tray “hat” 17 units TKR subsystem Flight grid reamed holes 4 holes x 4 sides Mechanical subsystem ACD mounting points 3 points x 4 sides ACD subsystem Feeler gauges 2 units I&T Optical Survey Test Equip and Setup • The optical surveys will be performed with a laser tracker supplied by the SLAC Metrology Department. • The Laser tracker(s) require continuous line of sight to the sphere mounted reflector as it is moved from the laser tracker test point to the measurement point. • The laser tracker will be mounted on stands to allow the laser tracker to view all reflectors. • All surveys will be performed in the SLAC Building 33 LAT integration facility. • Room temperature controlled to within 5 oC (TBR) • I&T will provide the Survey Scientist for analysis of data from surveys GPR GRID TKR Source: LAT-MD-01586

14. Mass Properties • The Integration and Test mass properties measurement plan is: Mechanical Weight and CG Plan LAT-MD-01598 Integration and Test Flow Test Plan Flow

15. Mass Properties • WEIGHT DETERMINATION • Weights of all LAT flight subsystem and MGSE elements will be measured to an accuracy 0.025% of its determined weight. • CENTER OF GRAVITY MEASUREMENT • Cg measurement of all LAT flight subsystem elements will be performed to an accuracy of ±1.0 mm [± 0.039 inch]for X, Y and Z axes (axes as defined in LAT-TD-00035, LAT Coordinate System). • Cg measurement of the integrated LAT (minus radiator hardware as described above) will be performed to an accuracy of ±2.0 mm [± 0.079 inch] in the X and Y axes and Z axes. • Cg measurement of the LAT Vibe Test Fixture will be performed to an accuracy of ±2.0 mm in the X, Y and Z axes. • Cg measurement of the LAT Transport Container will be measured to within ± 152 mm [± 6 inches] for the X, Y and Z axes. • Definition of the LAT Transport Container axes is to be consistent with the LAT when mounted inside the container.

16. Modal Survey • The system level requirements are defined in the LAT Dynamics Test Plan LAT-TD-001196. • The I&T plan to implement the Modal Survey is in the LAT Dynamics Test Performance Plan LAT-MD-01836. Integration and Test Flow Test Plan Flow

17. LAT Modal Survey • Test goals • Validate the LAT structural finite element analysis (FEA) model by correlating with test results • Measure all primary modes of the LAT/Grid structure. • Measure the first mode, and all modes predicted to have high mass participation, for every subsystem • Measure as many natural frequencies of the LAT up to 150 Hz as practical • Test results will be used to evaluate the predicted expected modal frequencies and mode shapes, and used to modify the structural FEA, if needed. • Finalize test environments and notching plans for sine vibration testing • Configuration • Fully integrated, except the Radiators are not mounted • Supported off of its spacecraft (SC) mount brackets, • +Z-axis point vertically up • LAT powered off during testing Source: LAT-MD-01196-01, “LAT Dynamics Test Plan,” March 2003

18. LAT Modal Survey • Instrumentation • High-precision accelerometers mounted to the LAT and test stand • Specialized test equipment requirements • LAT supported by the Vibe Test Plate which provides a rigid support of each mount point • Vibe Test Plate sits on a massive base-isolated table, to damp high-frequency base noise being transmitted to the structure • Excited using two stingers, located under the LAT ACD Accelerometer Placement TKR, CAL, and Grid Accelerometer Placement CAL Bottom and E-Box Accelerometer Placement Source: LAT-MD-01196-01, “LAT Dynamics Test Plan,” March 2003

19. LAT Modal Survey Test • Test sequence • Excite LAT at two -X corners in the Z-direction, in phase • Excite LAT at two -X corners in the Z-direction, 180 degrees out of phase—intended to excite LAT “potato chip” mode and other anti-symmetric twisting modes • Excite LAT at two -X corners in the X-direction, in phase—intended to excite LAT, ACD, TKR, and CAL lateral modes • Excite LAT web crossings on either side of the Grid center from the underside—intended to excite LAT drumhead mode • Test levels • TBD • Levels will be set, based on pre-test analysis using as-measured damping coefficients for subsystems Source: LAT-MD-01196-01, “LAT Dynamics Test Plan,” March 2003

20. Modal Test Setup • Test will be at SLAC because we will need to remove ACD to uninstall/install appropriate accels before shipment to NRL. • Soft Suspension System With Mass Loaded Interface • Pneumatic Isolators used to support system (provided by NRL) • LAT Mounted to Steel Plate - Reaction Mass (provided by SLAC) • NRL will provide the monitoring equipment • Test accelerometers are supplied by TBD depending on final release of the Instrumentation Plan .

21. EMI/EMC Tests • The system level requirements are defined in the LAT EMI/EMC Test Plan (TBD). • The I&T plan to implement the EMI/EMC Test is in the LAT EMI/EMC Test Performance Plan LAT-MD-01838. Integration and Test Flow Test Plan Flow

22. EMI/EMC Tests • Purpose • Ensure compatibility of LAT with other space vehicle systems • Ensure compatibility of other space vehicle system with LAT • Demonstrates that adequate margin exists between susceptibility and noise levels • Configuration • LAT will be integrated with EMI skirt, X-LAT plates installed and radiators not installed • Applicable Documents • LAT EMI Test Plan, LAT-MD-TBD • LAT Environmental Parameters Specification, LAT-SS-00778 • LAT Program Inst. Performance Verification Plan, LAT-MD-00408 • MIL-STD-461E • GSFC 433-RQMT-0005 (Draft) Source: GSFC 433-RQMT-0005 (Draft)

23. EMI/EMC Test Suite • Actual test levels will be updated from those shown

24. EMI/EMC Testing Facility • EMI/EMC Testing will be performed at the NRL facility • 2 Chambers, GLAST is currently scheduled to use the smaller chamber • 19' clearance tip to tip on the cones • door 10.5' wide by 10' high, 0.5" rise from exterior floor (minimal floor rise is reason for selecting this chamber) • Capable of MIL-STD-461 testing up to 18 GHz RS, 40 GHz RE Photo caption: Windsat @ NRL And there is a bigger chamber.

25. Sine Vibration Test • The system level requirements are defined in the LAT Dynamics Test Plan LAT-TD-001196. • The I&T plan to implement the Sine Vibration Test is in the LAT Dynamics Test Performance Plan LAT-MD-01836. Integration and Test Flow Test Plan Flow

26. Sine Vibration Test • Test goals • Verify the LAT’s ability to survive the low frequency launch environment • Test for workmanship on hardware such as wiring harnesses, MLI, and cable support and strain-reliefs which will not have been fully verified at the subsystem level • Interface verification test for subsystem structural interfaces to the LAT Grid • Qualify LAT-SC interface • Configuration • Fully integrated, except the Radiators are not installed • Supported off of its spacecraft (SC) mount brackets, on the Vibration Test Stand • The LAT is tested in all three axes, X, Y, and Z independently, requiring re-configuration between tests • The LAT is powered off during sinusoidal vibration testing, and the EGSE cable harnesses removed Source: LAT-MD-01196-01, “LAT Dynamics Test Plan,” March 2003

27. Sine Vibration Test • Instrumentation • Accelerometers mounted to the LAT and test stand, to cover the entire dynamic range predicted for the LAT and subsystems (LAT Instrumentation Plan, LAT-MD-00890) • Specialized test equipment requirements • The Vibe Test Stand must support the LAT at the SC interface with flight-like connections • The Stand must allow for reconfiguration to alternate axes, with the LAT attached, to avoid unnecessary handling TKR, CAL, and Grid Accelerometer Placement Source: LAT-MD-01196-01, “LAT Dynamics Test Plan,” March 2003

28. 4 4 Sine Vibration Test • Test sequence • X-Direction Sine Vibe • Low-level vibration to verify that all instrumentation is operational • Low-level random vibration signature of the entire frequency range • Acceptance level sweep • PFQ level sweep • Low-level random vibration signature • Limited Performance Test—re-connect E-GSE cabling; execute LPT while still on vibe test stand • Y-Direction Sine Vibe • Low-level random vibration signature • Acceptance level sweep • PFQ level sweep • Low-level random vibration signature • Z-Direction Sine Vibe • Low-level random vibration signature • Acceptance level sweep • PFQ level sweep • Low-level random vibration signature • Limited Performance Test—re-connect E-GSE cabling; execute LPT while still on vibe test stand • Test levels • Levels will be established with pre-test analysis to 1.25 times the static-equivalent acceleration values, without exceeding interface limit loads 4 LAT Sine Vibration Minimum Test Levels Source: LAT-SS-00778-01, “LAT Environmental Specification,” March 2003 Source: LAT-MD-01196-01, “LAT Dynamics Test Plan,” March 2003

29. Sine Vibration Test Facility Facility Capability • Four electrodynamic shakers (one 40-klb, one 30-klb, and two 18-klb) • Two slip tables • Three power amplifiers • The 40-klb shaker will be replaced with a 50-klb unit ~ Nov 2003 • LAT will use the 50-klb unit Testing will be performed at the NRL Naval Center for Space Technology Photo caption: Coriollis during vibration testing @ NRL

30. Acoustic Test • The system level requirements are defined in the LAT Dynamics Test Plan LAT-TD-001196. • The I&T plan to implement the Acoustic Test is in the LAT Dynamics Test Performance Plan LAT-MD-01836. Integration and Test Flow Test Plan Flow

31. LAT Acoustic Test • Test goals • Verify the LAT’s ability to survive the acoustic launch environment • Test for workmanship on LAT hardware, especially that hardware which responds to acoustic loading • Validate the acoustic analysis • Configuration • LAT is fully integrated, including the Radiators • Mounted to STE using the flight-configuration bolted joint • LAT +Z-axis vertical, and with Radiators integrated to the Grid as well as to the STE at the SC strut mount points • LAT is powered off during acoustic testing, and the E-GSE cable harnesses removed • Instrumentation • Accelerometers mounted to the LAT and test stand (per LAT Instrumentation Plan, LAT-MD-00890) • Microphones mounted around the LAT • Specialized test equipment requirements • The Vibe Test Stand must support the LAT in the same degrees of freedom as the SC flexures, to avoid over-constraining the Grid and Radiators • The STE fills the volume between the Radiators, so must approximate the acoustic behavior of the SC TKR, CAL, and Grid Accelerometer Placement Radiators Accelerometer Placement Source: LAT-MD-01196-01, “LAT Dynamics Test Plan,” March 2003

32. LAT Acoustic Test (cont) • Test sequence • Low-level acoustic to verify that allinstrumentation is operational andtaking useful data • Acceptance level test—ramp up soundpressure level (SPL) to AT levels • PFQ level test—ramp up SPL to QTlevels • Ramp down SPL and turn off • TBD modal signature test • Limited Performance Test—re-connectE-GSE cable harnesses and execute LPT • Test levels • Fairing SPL’s are shown • Final SPL’s for testing will be determinedby pre-test analysis, to factor in fill-fractionin acoustic chamber LAT Acoustic Test Levels Source: LAT-SS-0077801, “LAT Environmental Specification,” March 2003 Source: LAT-MD-01196-01, “LAT Dynamics Test Plan,” March 2003

33. NRL Acoustic Chamber • LAT will mount on a special stand to accommodate radiators. (TBD) • Support test stand will sit on floor of reverberant acoustic chamber • NRL chamber capabilities: sound pressure level of 153 dB through a range of 32-10,000 Hz • Coriolis / Windsat system shown here on test stand Photo caption: Coriollis/Windsat @ NRL

34. LAT Thermal Balance/Thermal-Vacuum Tests • The system level requirements are defined in the LAT Thermal Test Plan LAT-TD-001600. • The I&T plan to implement the TBAL/TVAL Testing is in the LAT Thermal Test Performance Plan LAT-MD-01837. Integration and Test Flow Test Plan Flow

35. LAT Thermal Balance/Thermal-Vacuum Tests • Test goals • Thermal-Balance • Verify that the LAT thermal control system is properly sized to keep maximum temperatures within mission limits, while demonstrating at least 30% control margin • Validate the LAT thermal control system control algorithms • Verify that the VCHP control effectively closes the radiator to when the LAT is off • Validate the LAT thermal model by correlating predicted and measured temperatures • Thermal-Vacuum • Verify the LAT’s ability to survive proto-qualification temperature levels at both the high and low end • Test for workmanship on hardware such as wiring harnesses, MLI, and cable support and strain-reliefs which will not have been fully verified at the subsystem level • Demonstrate that the LAT meets performance goals at temperature • Provide stable test environment to complete LAT surveys, as detailed in LAT-MD-00895, “LAT Instrument Survey Plan” • Configuration • The LAT instrument will be fully integrated but the SC solar arrays will not be installed • The LAT will be powered on and off during testing per the test procedure • The LAT will be oriented with the Z-axis parallel to the ground to allow all heatpipes to operate and the +X axis facing up • All MLI blanketing will be in its flight configuration for the duration of the 2 tests • The LAT will NOT be reconfigured after the thermal-balance test Source: LAT-MD-01600-01, “LAT Thermal-Vacuum Test Plan,” March 2003

36. LAT Thermal Balance/Thermal-Vacuum Tests • Instrumentation • Thermocouples and RTD’s will be used to instrument the LAT and test chamber • LAT flight housekeeping instrumentation includes many thermistors and RTD’s. These will also be used for monitoring temperatures within the LAT • Specialized test equipment requirements • Chamber pressure of < 1 x 10-5 Torr • Chamber cold wall temperature of –180 oC to provide a cold sink for accumulation of contaminants • Thermally controlled surfaces in the chamber • 5 plates for ACD surfaces, each individually controlled • 2 plates for the radiators(one for each side), each individually controlled • 1 plate to simulate the bus, controlling the environment to the X-LAT Plate and the back of each radiator • Heat exchangers mounted on the + / – X sides of the LAT Grid, to increase ramp rate during transitions • LAT heat pipes will be leveled to within 0.2 degrees • 20 degC/hr max ramp rate • Facility capable of holding LAT stable to < 2 oC/hr rate of change (TBR) • Handling fixture to allow the transition from acoustic test to TVAC without breaking radiator configuration Source: LAT-MD-01600-01, “LAT Thermal-Vacuum Test Plan,” March 2003

37. LAT Thermal Balance/Thermal-Vacuum Test Profile • Dwell at high and low temps for 12 hours, min • Limited Performance Tests conducted during transitions • Comprehensive Performance Tests (C) • CPT test regime performed at ambient, during cold and hot soaks, and at return to ambient • Limited Performance Tests (L) • LPT test regime performed as indicated. Operating modes will be checked and units will be monitored for failure and intermittent operation Source: LAT-MD-01600-01, “LAT Thermal-Vacuum Test Plan,” March 2003

38. LAT Thermal Balance/Thermal-Vacuum Test Profile LAT Thermal-Vacuum Test Profile Source: LAT-MD-01600-01, “LAT Thermal-Vacuum Test Plan,” March 2003

39. Thermal Test Facility • NRL Naval Center for Space Technology A59 facility • Cryopumped chamber • 16’ diameter x 30’ long • Support 200-300 thermocouples, ~400 other circuits

40. LAT Airplane Test (TBR) • Expose the LAT to charged particle fluxes similar to those in orbit. Do an End-to-End test of the LAT in as close to orbital environment as practical. This test is for risk reduction. • Demonstrate the complete LAT system functionality at in-orbit cosmic rates and higher. See LAT-TD-00550 “LAT Test Plan for Airplane”. Constitutes an end-to-end test of the LAT. • General hardware tests for the complete LAT system at high particle rate: • Verify DAQ operation at estimated orbital rates. • Verify event quality. • Verify trigger functionality in the various trigger modes at estimated orbital rates. (Much higher than ground cosmic rays). • Measure livetime in the various trigger modes as determined by LAT hardware.

41. EXTRA SLIDE

42. Pass/Fail Criteria • Modal Survey: • Successful correlation of dynamics model • EMI/EMC: • Emissions for the LAT below required levels Susceptibility: LAT does not exhibit susceptibility when exposed to required levels • Sine vibe: • No change in modal frequencies • LAT functions properly post test • Thermal Balance: • successful correlation of thermal model • Thermal vacuum testing: • Verify ability to operate successfully over required temperature range • Successful completion of performance tests • Successful completion of cosmic ray muon survey