1. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem1 GLAST Large Area Telescope: Mechanical Systems WBS: 4.1.8 Section 13 Marc Campell SLAC Mechanical Systems Manager marcc@slac.stanford.edu Gamma-ray Large Area Space Telescope

2. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem2 Overview Section 13.1 Gamma-ray Large Area Space Telescope

3. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem3 Mechanical Systems Organization

4. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem4 Mechanical Subsystems Overview +Z Mid-Plate X-LAT Plate Assy +Z EMI Shields SC “wings” Grid Assembly Radiator Mount Bracket Grid Box Assembly

5. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem5 Radiator Placement +Z

6. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem6 Major Subassemblies Grid Box Assembly –Mechanical Systems Top Assembly test configuration –Static Load and Thermal Cycle tests Grid Box Base Assembly –Configuration delivered to I & T for LAT integration –Defines base configuration for LAT assembly drawings Grid Assembly –Mechanical backbone Radiators –Fabricated and tested by LM X-LAT and Mid-plates –Fabricated and tested by LM

7. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem7 Design & Fabrication Responsibilities Manufacturing/Integration Activity Manufacturing/Integration Activity Quantity Flt/Spare Responsible Organization Work Performed Grid Assembly Fabricate, inspect Grid structure1 / 0SLACSub Fabricate, test Top Flange heat pipes5 / 1LM-ATCLM-HPPC Fabricate, test Downspout heat pipes12 / 1LM-ATCLM-HPPC Assemble, test Grid assembly1 / 0SLAC Fabricate, inspect EMI Skirt parts1 / 0SLAC X-LAT Thermal Plate Fabricate, inspect X-LAT Plate partsLM-ATCLM Fabricate, test X-LAT heat pipes9 / 1LM-ATCLM-HPPC Assemble, test X-LAT Thermal Plates2 / 1LM-ATC Assemble, test mid-plate1 / 0LM-ATC Radiators Fabricate, inspect Radiator partsLM-ATCSub Fabricate, test Radiator VC heat pipes12 / 1LM-ATCLM-HPPC Assemble, inspect Radiators2 / 0LM-ATCLM-HPPC Test RadiatorsLM-ATC Thermal Control System Fabricate TCS hardware1 / 1SLACSub Thermal-balance test TCS system1 / 0LM-ATC Legend LM-ATCLockheed-Martin Advanced Technology Center, Palo Alto CA LM- HPPC Lockheed-Martin Heat Pipe Product Center, Sunnyvale CA SLACStanford Linear Accelerator Center, Menlo Park CA SubSubcontractor to be determined Mechanical Systems

8. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem8 Design Problem Areas CAL-GRID Interface Electronics-Box to X-LAT Interface

9. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem9 CAL-GRID Interface Design Problem Status At PDR & dPDR the baseline design was a bolted interface that relied on friction between the CAL plates and the Grid to react shear forces. By Peer Review, we had not demonstrated (EM test) that we could develop the coefficient of friction required at the most highly loaded (<10% of) locations with ample margin. A pinned approach was implemented and analyzed.

10. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem10 CAL-GRID Interface Design Problem Resolution The pins cannot carry the loads at the highly loaded locations. Request to GSFC to re-evaluate loads that were specified to LAT which we believe may overstate the shear loads by a factor of 2 or 3 (but correctly state the SC – LAT interface loads) Acceptable options that impact only Mech have been exhausted or rejected on principal Other options under evaluation which impact at least the CAL subsystem as well

11. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem11 X-LAT to Electronics-Box Thermal Joint Design Problem Status At PDR & dPDR the baseline design was a bolted and thermally bonded joint between bottom of each E-Box and the X-LAT plate. There were flexures between the top of the E-box stack and the CAL plates. –Concern raised that E-boxes were not serviceable Large bonded area to de-mate. Re-verification issues after re-integrating. For Peer Review, trade study presented for design that –Carried the thermal load of E-Boxes into X-LAT heat pipes –Accommodate tolerance buildup from E-Box and Grid Box components –Repeatable interface (make & break) –Minimize schedule & verification impacts resulting from X- LAT plate removal for Electronics box access

12. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem12 X-LAT to Electronics-Box Thermal Joint Design Problem Resolution Design changed to rigidly mount E-Box stack to CAL plate and create a thermally compliant thermal joint between the E-box & X-LAT plate Trade study results indicate that Vel-therm gasket material optimally meets requirements and has the following characteristics: –Highly conductive graphite fibers –Mechanically compliant –Meets out-gassing requirements –Allows TEM/TPS to be mated to CAL through out its Acceptance testing However, this approach has little Flight heritage and must be qualified for our application

13. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem13 Peer Review Significant Findings Spacecraft to LAT mechanical interface finalization Structural analysis and design margins not finalized X-LAT to electronics box mechanical & thermal design not finalized –Unconventional design approach dependent on analysis results and engineering model development Immature drawing/document status for grid and X-LAT plate Calorimeter to grid interface concerns must be resolved

14. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem14 Peer Review Significant Findings Is the design maturity, qualification and verification planning near CDR level? –With the exception of the electronics to X-LAT interface, Yes, but still missing an appropriate level of verification with the engineering models and final dynamics analysis. Has the Subsystem identified open design issues and established appropriate resolution plans to ensure closure? –Yes, the issues have been identified but issues may still develop during engineering model testing and final analysis. Is the Subsystem near readiness for manufacturing? –Many element of the subsystem are ready for manufacture (e.g. radiator), however other items need to wait until analysis and successful engineering model completion. Has the Subsystem identified open manufacturing issues and established appropriate resolution plans? –Yes. Specific concerns are captured in the RFAs. Are there other issues that should be addressed? –Mechanical assembly of the LAT will be a complex process that will require development of detailed processes and procedures. –The mechanical team has just recently staffed up. Re-plan of work that has been delayed needs to be completed and may delay design finalization

15. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem15 Major RFA’s and Overall Status 19 of 46 RFA’s owned by Mechanical Systems –0 closed –X submitted –Y open, ECD June 1 st –Z open, ECD July 1 st

16. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem16 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 1Open/Closed 10 12 27 28

17. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem17 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 29Open/Closed 32 33 34 36

18. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem18 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 37Open/Closed 38 39 40 41

19. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem19 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 42Open/Closed 43 45 46

20. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem20 Mechanical Systems’ Status Summary Final Design Established With Known Closure Plans For Design Trades –X- LAT Plate To Electronics ICD - ECD: 7/15/03 –Xx/yy Drawings Complete, zz/yy Drawings Draft – ECD 8/15/03 –EM Model Tests Complete - ECD: 7/28/03 Internal & External Interfaces Established –Yy TBX’s with closure planned – ECD: 7/12/03 Performance Analyses Show Compliance Including Sufficient Design Margin –Any Exceptions noted with recovery plans Qualification & Verification Plans In Place Subsystem Risk Areas Identified And Mitigation Plans Established Cost & Schedule Manageable –$$ Variance with recovery plans established –XX Week Schedule Float to Flight Delivery Need Dates

21. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem21 Summary Mechanical Systems detailed design and analysis indicates that all requirements will be met. Mechanical Systems has accommodated changes since dPDR. Overall design is in good shape –Grid Box Assembly design is nearly complete. –Radiator and Heat Pipe designs are nearly complete. –Cal-Grid interface is still in development. –Risk list items are understood & mitigation plans are in place. Radiator design has matured and fabrication will begin after I- CDR. Aluminum billets for Grid are on order. LM’s X-LAT team has come up to speed quickly and made several design improvements. LM has team in place to execute to their plan.

22. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem22 Summary (con’t) Plans for Further Work Engineering Modeling –Complete the remaining testing Analysis –Complete detailed part stress analysis –Define Grid Box Assembly SLT cases Design –Release Radiator and X-LAT specifications & Interface Def. Dwg. –Finalize CAL-Grid interface & incorporate into design –Finalize wing, EMI skirt & Radiator mount Bracket designs –Finalize X-LAT to Electronics design Lockheed Martin –Complete detailed design and analysis –Finalize test plans Program Management –Negotiate & award LM Phase II (fabrication) contract –Award Grid Assembly contract

23. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem23 Gamma-ray Large Area Space Telescope Requirements Section 13.2

24. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem24 Topics Agenda Mechanical Systems Mass Budget Mechanical Systems Power Budget Requirements Flow down And Document Status Key Mechanical Systems Requirements (Level 3) Heat Pipe Performance Requirements Radiator Design Requirements Main X-LAT Design Requirements Driving X-LAT Thermal Requirements

25. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem25 Mechanical Subsystem Mass Budget

26. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem26 Mechanical Systems Power Budget Operational Mode Power Allocation,W Estimate,W Nominal Operation 35 20.4 Survival 220 152.0

27. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem27 LAT Stay-Clear Drawing LAT-DS-00040-5 Mech Systems Subsystem Spec LAT-SS-00115-2 Subsystem ICD’s LAT Thermal Design Param’s LAT-TD-00224-3 LAT Dissipated Power Summary LAT-TD-00225-3 Radiator Design Spec LAT-SS-00394-1 Grid Box Design Spec LAT-SS-00775-1 Thermal Control Sys. Perf. Spec LAT-SS-00715-1 LAT Instrument Layout Dwg LAT-DS-00038-3 Top Flange Heat Pipe SCD LAT-DS-01393-1 Subsystem IDD’s LH/RH Down Spout Heat Pipe SCD LAT-DS-01392-1 LAT-DS-01393-1 Radiator IDD LAT-DS-01221-1 LAT Perf Spec LAT-SP-00010-1 31 Aug 2000 X-LAT Design Spec LAT-SS-001240-2 X-LAT Plate SCD LAT-DS-01247-1 Mid-Plate SCD LAT-DS-01257-1 LAT Envir. Spec LAT-SS-00778-1 10 Feb 2003 Requirements Flow-Down and Documentation Status

28. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem28 Key Mechanical Systems Requirements (1of 2) 8 Configuration 8.1. Mass The total mass of Mechanical Systems <345 kg 329.3 15.7 Y I LAT-TD-00125-1 8.3. Stay-Clear Volume and Dimensions Sect Requirement Design Margin Comply Method Req.Source Radiator positioned according to IRD Appendix A >1.89m 1.895 Y I IRD 3.2.2.3 When on, Radiator VCHP heater power < 35 W 20.4 14.6 Y D TD-00125-1(Derived) When off, orbit-average survival heater power 152.0 68(45%) Y D IRD 3.2.4.1.7.6 <220 W @ 27 V min When off, peak survival heater power < 560 W Ok Y T, A IRD 3.2.4.1.7.6 (Derived) 8.5. Stiffness Fixed-base first-mode > 50 Hz 55.5 Hz 11% Y T IRD 3.2.2.8.1.2 8.6. Provisions for Integration and Test During Obs T-Vac, TCS capable of full functionality Ok Y T, A IRD 3.2.2.8.1.2 “lying on its side” 387 W@ 35V (incl 30% Control margin)

29. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem29 Key Mechanical Systems Requirements (2 of 2) 9 LAT Alignment 9.1. Alignment Stability Maintain TKR alignments to < 7 arc-seconds,1 s radial, Y T, A MSS 3.3.1.11.1.2 Sect Requirement Design Margin Comply Method Req.Source Capable of withstanding static loads in thrust and lateral Ok Y A IRD 3.2.2.8.2 Capable of exposure to static launch loads Ok Y T, A IRD 3.2.2.8.2 10 Structural Load Environment Provide thermal control with LAT pointed 2pi/24/7/365 Y T, A MSS 3.3.2.3 simultaneously Maximum process power indefinite dissipation Y T, A IRD 3.2.4.1.1 (Derived) 11.3. Environment Heat Loading and Orbital Parameters Capable of maintaining thermal control during exposure Y T, A IRD 3.2.3.5 Capable of normal operation when loaded by 75 W/Rad Y T, A IRD 3.2.3.4.5 From SC solar arrays 4.1 arc-sec Peak to-Peak 2.9 arc-sec + 5 s during normal LAT operation 10.1. Structural Loads 11.1. Process and Interface Heat Loads 11 Thermal Environment and Heat Loads 612W LAT+ 38W Rad @ 24 deg C 73.4W/Rad 0W/Rad 5 degC calc+ 1 deg C operating during any normal LAT mode to IR, Albedo, Solar fluxes (Derived)

30. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem30 Heat Pipe Performance Requirements Based on:Results of Overall LAT Thermal Math Model Verification Methods A: Analysis T: Test Margin is determined by: EP/Req Must be > 1.3

31. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem31 Driving Design Requirements (Radiator: Mechanical)

32. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem32 Driving Design Requirements (Radiator: Structural)

33. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem33 Driving Design Requirements (Radiator: Thermal)

34. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem34 Driving Design Requirements (X-LAT)

35. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem35 Gamma-ray Large Area Space Telescope Design Grid Box Assembly Section 13.3

36. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem36 Drawing Tree

37. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem37 Grid Box Assembly Design +Z Heat Pipe Patch Panel S/C Mount Interface Mid-Plate X-LAT Plate Assy Radiator Mount Bracket EMI Shields CAL-Grid Interface

38. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem38 Grid Design Drivers Provides structural backbone for all LAT Subsystems Provides electrical ground for all LAT Subsystems Provides thermal path to Radiators for all LAT Subsystems except Electronics boxes (carried by X-LAT plates) –Embedded Heat Pipes in top flange of Grid to move heat out –Downspout Heat pipes tie Grid to Radiators Thermostatically controlled heaters on Grid corners are part of LAT thermal control system Construction Machined from 10” thick 6061 AL plate Heat treated to T6 after rough machining Grid surface is alodine, class 3. Electrically conductive and good surface for adhesive bonding thermal components, harness supports, Tracker cables, MLI supports, EMI tape etc Integral purge grooves allow for N2 purging of the CAL’s during ground operations

39. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem39 Grid Structure +Z Helicoils for CAL bolts Top Flange Heat Pipes Purge grooves

40. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem40 Calorimeter to Grid Interface This interface is part of the Grid stiffness design. Interleaved CAL baseplate tabs are bolted to –Z surface of Grid CAL baseplates close-out the Grid structure which increases natural frequency of LAT Bolted interface applies clamping force over large area (~4223 mm 2 per CAL) to develop shear load capability 2 pins per Grid bay locate CAL and are used to locate hole pattern in Grid and other features such as Tracker cable cut- outs in Grid walls Perimeter backing bars engage the outer tabs of the outer CAL’s to double the clamping force on these highly loaded tabs

41. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem41 X-LAT Plate to E-Box Thermal Joint Thermal joint design drivers –Carry thermal load of stack of E-Boxes into X-LAT Heat Pipes –Accommodate tolerance stack up E-Box and Grid Box parts –Be repeatable & reliable –Minimize schedule & verification impacts due to removal of X-LAT plates for access to Electronics Vel-therm gasket material selected –Highly conductive graphite fibers –Mechanically compliant –Meets out-gassing requirement

42. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem42 Electronics Stack Cross-Section Note: View along Y-axis Midplate to X-LAT Thermal Joint, 2 PLCS, Approx. 60 #6 Fasteners each side EMI Shields EMI Shields GRID Bolting X-LAT Plate to EMI Shields, Approx. 60 #8 Fasteners per Plate X-LAT PlateMidplateX-LAT Plate Vel-Therm 4 cm wide Vel-Therm strip placed around perimeter of each box optimizes conduction vs contact pressure required

43. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem43 EMI Shield Design Drivers Encloses LAT Electronics boxes (EMI tight) Consists of 4 Radiator Mount Brackets, 4 Heat Pipe Patch Panels, 4 X-side Shields and 4 center Shields Mechanically supports 3 way heat pipe joint – Downspout, X- LAT and Radiator HP’s Supports X-LAT plates Provides mounting for Connecter Patch Plates from Electronics Provides for venting of enclosure Construction 6061-T6 AL machining, alodine Pieces bolted to Grid & each other +Z

44. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem44 Radiator Mount Bracket Design Drivers Supports & locates Radiators & their Heat Pipes Supports & locates X-Lat Plates & their Heat Pipes Provides access to ACD mounting bolts Supports & locates alignment optic Provisions for mounting Heater Control Box or Heater Control Connector Bracket for Thermal Control System Corner lugs for MGSE attachment (sized to carry entire Observatory mass with 2 lugs if required) Construction 6061-T6 Al machining, alodine Bolts to 3 orthogonal surfaces of Grid corner

45. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem45 Spacecraft Interface Stiffener (Wing) Design Drivers Primary function is to spread the point load inputs from the Spacecraft & locally stiffen the Grid against the lateral loads. –Distortions in this area drive the CAL-Grid interface design Defines Spacecraft interface to LAT (bolted – pinned joint) Construction 6061-T6 machining, alodine Bolted, pinned & keyed to Grid +Z

46. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem46 Work to Close Out Structural Design CAL-Grid interface under review with GSFC Finalize design of perimeter backing plate Investigating making the Spacecraft Interface (Wing) an integral part of the Grid Finalizing details of Spacecraft mounting w/ Spectrum Mass & stress optimization of EMI shields and Radiator mount brackets Radiator mount bracket X axis compliance requirement for differential contraction of Radiators & Grid –Awaiting results of LM thermal analysis Finalize design implementation of Vel-therm joint

47. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem47 Stress Analysis Topics Cal-Grid interface load recovery Grid Stress analysis Radiator Mount Bracket analysis Summary and Closure Plan

48. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem48 CAL Interface Load Recovery CAL-Grid bolted friction joint –1152 screws (72 per CAL module) –Joint allows CAL bottom plate to stiffen LAT by closing out bottom side of Grid Load recovery –Interface loads are backed out from the FEA model by resolving nodal forces at the interface into shear and normal loads at the bolt locations –Required friction coefficients are generated, given a set screw preload and a perimeter backing strip –EM bolted joint tests are underway to validate friction coefficient and joint behavior Histogram Showing Required Friction Coefficients Qual Friction Coefficients for CAL-Grid Joint

49. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem49 Grid Stress Analysis Grid stress analysis indicates positive margins of safety for all regions Highest stresses occur in transition regions around SC mount –Nominal maximum Von Mises stress is order of magnitude below yield for material –Large corner radii in the actual design, not included in the model, limit stress risers –Top flange in model has a weighted-average cross section which is no more than twice the minimum cross sectional area Grid material properties –Material: 6061-T6 aluminum (6061-T651, stress-relieved, then heat- treated during fabrication) –Sy = 240 MPa (35 ksi) –Su = 290 MPa (42 ksi) Factors of safety (per NASA-STD-5001) –Metallic structures Yield: FS y = 1.25 Ultimate: FS u = 1.4

50. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem50 Radiator Mount Bracket Analysis Design Loads and critical load cases –Loads defined in Environmental Spec FS=1.25 (PFQ) used for launch loads FS=1.40 used for lift case –Assume Observatory lift load is carried in 2 of 4 fittings –Critical Load Cases Studies Lift case induces the highest stresses Margins of safety are good for all design cases Calculated stiffness is high, which is conservative for loads determination The radiator attachment bracket meets or exceeds all design requirements CASEX [N]Y [N]Z [N] +X/-Z9940-1670 -X/-Z-9940-1670 +Y/-Z0333-1670 -Y/-Z0-333-1670 LIFT0032400

51. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem51 Summary and Closure Plan Summary –Integrated LAT structural analysis results of the static- equivalent load cases indicate that LAT deflections and stresses are within required limits –Grid stress analysis shows that the Grid design is not highly-stressed, but driven more by the natural frequency requirement Tasks Remaining –Finalize design of the SC mount region with the SC contractor and complete stress analysis –Complete stress analysis on EMI skirt pieces

52. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem52 Grid/Grid Box Assembly Verification Topics 4 x4 Grid Verification Grid Box Assembly Verification

53. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem53 4 x 4 Grid Structure Verification Mass Properties & C.G. Verified Dimension Check Verified Proof Test of Inserts

54. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem54 Grid Box Assembly Verification Grid Box Assembly Dimension Check Grid Box Assembly Mass Properties/C.G. Grid Box Assembly Alignment Check Grid Box Assembly Functional Test Grid Box Assembly Thermal Cycle Grid Box Assembly Functional Test Grid Box Assembly Static Load Test

55. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem55 Static Load Test Test Objectives –Primary Objective: Verify static strength and stability of the Grid Box Assembly under worst case Delta II-H vehicle loads of 1.25 times limit loads Achieve maximum stresses in grid box assembly Load subsystem interfaces to qualification design loads –Secondary Objective: Verify the design analysis process by comparing measured strains and deflections to predictions from the finite element analysis model Test Success Criteria –Successful test completion is when all load cases have been performed and it is verified that no yielding, buckling, de-bonding, or fractures have been observed. A visual inspection is to be performed after each load case to check the critical joints and bonded interfaces A review of all pertinent data during test including deflections and strains to verify linearity

56. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem56 Grid Box Static Load Test Configuration The test configuration consists of all primary structure grid box components as described below The test article will be grounded at the SC Mount Brackets with correct degrees of freedom Radiator Mount Brackets - 4X - Flight EMI Skirts - Flight XLAT Plate - Flight Grid - Flight Down spout HPs - 12X - Flight Calorimeter Plates -16X - Flight-like Spacecraft Mount Brackets - 4X - Flight

57. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem57 Gamma-ray Large Area Space Telescope Verification Program Grid Box Assembly Section 13.4

58. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem58 Verification Topics EM Test Plan Overview EM Closure Plan Summary Qualification & Flight Test Overview Mechanical Systems Verification Test Flow Mechanical Systems Verification Matrix Heat Pipe Qualification/Acceptance

59. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem59 EM Test Plans Overview EM test plans developed for: –CAL-Grid Joint Testing Friction characterization Bolt-Helicoil pair characterization Pull tab coupons –1x4 Grid –Grid heat pipe bonding process qualification –Joint candidates “Wet” adhesive or gasket Low contact pressure No contact pressure –X-LAT heat pipe characterization

60. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem60 CAL-Grid Joint Testing CAL-Grid joint is a friction joint between the CAL baseplate tabs and the Grid walls. –70 fasteners around the perimeter of the CAL 54 #8, 16 #6 fasteners and 2 -.156” dia alignment pins –Helicoils used in Grid walls To maximize the load carrying capability of the joint –Maximize bolt clamping force –Maximize friction at interface Tests performed –Friction Characterization –Bolt – Helicoil pair characterization tests –Pull Tab Coupons

61. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem61 1 x 4 Grid Planned Tests Purpose: Validate finite element model used for LAT predictions to date –Model created from full up model –Full scale CAL-Grid interactions Test Set up: 1 x 4 Grid design is flight like –Partial bays with partial CAL plates provide interleaving CAL tabs –Load hydraulically applied 6 places –Reacted out at corners –Deflections measured along length –Record load vs deflection 1 x 4 Grid

62. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem62 Planned Process Tests 1 x 4 Grid unit fabrication Objectives –Demonstrate Grid manufacturability (currently has UNC inserts –Demonstrate purge gas system –Provide unit to I&T group for I&T EM testing Risks mitigated or retired –Fabrication errors, process problems (cost & schedule impact)

63. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem63 3-Way Heatpipe Thermal Joint Conductance Test 3-Way heatpipe thermal joint conductance test Objectives –Determine thermal joint that can meet conductance and ease of assembly requirement –Develop design-specific empirical conductance values for actual bolted joint configuration Risks mitigated –Validates thermal model based on empirical thermal conduction values

64. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem64 Thermal Joint Further Work Demonstrate Radiator installation process –6 wet RTV joints in vertical orientation –Complete within pot life limits (bonded & torqued) –Verify bond line integrity (uniform thickness & % voids) Demonstrate Radiator removal process –Separate 6 joints with limited access –No damage or distortions of heat pipes –Verify material can be cleaned up & surface prepared again for another bond

65. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem65 Joint Candidates Tested “Wet” adhesive or gasket joints –Thermally conductive silicone adhesive, Nusil CV2946 –SilPad, VO Gap Pad Low contact pressure joints –Off-the-shelf EMI gasket products, i.e. BeCu spring fingers, electrically conductive elastomers –Graphite velvet pad (Vel-Therm from ESLI) No contact pressure joints –High conductivity materials mechanically fastened at both ends –Formed Copper sheets (30 mils) –Pyrolytic Graphite Sheet (4 mils thick stock)

66. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem66 Thermal Joints EM Evaluation Summary Vel-Therm material is best candidate among those evaluated to meet all design drivers –Thermal data indicate material can meet required conductance –Material is bonded to one surface prior to installing X-LAT plate, minimal fasteners required –Allow sliding contact for lateral flexibility –Can bridge varying gaps from stack to stack with different stock thicknesses up to.125 inch thick max for single layer –Two Vel-Therms can be meshed together face-to-face for larger gaps up to.24 inch max

67. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem67 Further Work Integrated thermal analysis (including boxes stackup, heat paths and X-LAT thermal joint) to identify and alleviate “hot” spots (Electronics) Final detail design of EMI Shields, X-LAT Plate, Special Electronics box bottoms to accommodate Vel-Therm joint design – stack height Additional EM testing needed to retire risks –Conductance in high vacuum for dry tip contact –Sliding verification without generating loose fibers –Quantify contact pressure versus brush compression

68. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem68 Further Work (cont.) Proposed additional EM thermal joint test configuration for Vel- Therm material –Mock up box stackup configuration with heaters on sidewalls to simulate electronics heat source –Install cold plate and Vel-Therm sheet to simulate X-LAT and thermal joint –Flight like installation procedure for Vel-Therm to identify process problems and errors –Perform Random Vibe and Thermal Vacuum tests to retire risks associated with contamination, thermal conductance at min & max fiber compression levels

69. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem69 X-LAT EM Heat Pipe Characterization Tests Objectives –Verify thermal performance of EM X-LAT heat pipe in simulated on-orbit thermal cases Risks mitigated –Demonstrate adequate design margins –Assure that heat pipe performs as predicted

70. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem70 Heatpipe Characterization Test Setup CCHP Heatpipe ChamberClose-up of Cold Zone Cold Zone 1 Heat Zone 1 Heat Zone 2 Heat Zone 3 Heat Zone 4 Cold Zone 2 Tilt Meter Chilled Water Source

71. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem71 EM Closure Plan Summary

72. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem72 Qualification & Flight Test Overview The intent of the Mechanical Subsystem verification plan is to ensure that the component, assembly and subsystem hardware: - Verify workmanship and performance of hardware per Level III and IV subsystem specification - Provides traceability back to requirements in the Level III and IV subsystem specifications - Satisfies LAT Performance Specification (LAT-SS-00010) - Compatible with other LAT subsystem’s interfaces

73. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem73 Mechanical Systems Verification Test Flow Grid Structure -Proof Load -Mass Properties & C.G. -Dimension Check Radiator Mount Bracket Grid Box Base Assembly -Static Load -Thermal Cycle -Mass Properties & C.G. -Dimension Check -Alignment -Functional -Static Load Disassemble Grid Box Base Assembly X-LAT Plates Mid-Plate -Static Load Test -Mass Properties & C.G. -Dimension Check -Thermal Vacuum Test -Static Load Test -Mass Properties & C.G. -Dimension Check Radiator -Sine Sweep -Acoustic -Mass Properties & C.G. -Dimension Check -Interface Verification -EMI/EMC -Functional Assemble Radiator pair test configuration -Thermal Balance -Mass Properties & C.G. -Dimension Check LAT Integration LAT Level Verification Tests Grid Box Assembly X-LAT Plates Radiators Grid Assembly

74. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem74 Mechanical Subsystem Verification Matrix LEGEND Assembly Level Unit TypeVerification Method S – SubsystemPF – Proto FlightQ – QualT – Test TQ – Test, Qualification Level A- AssemblyF – FlightE – Engineering ModelA –AnalysisTA – Test, Acceptance Level C – ComponentS – SpareV – Verification ModelM – MeasurementP – Proof I – Inspection

75. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem75 Test Levels/Durations Table Shaded areas do not apply. 1- If qualified by analysis only, positive margins must be shown for load factors of 2.0 on yield and 2.6 on ultimate. Composite materials cannot be qualified by analysis alone. Note: Test and Analysis levels for composite strictures, including metal matrix, requires acceptance level testing to 1.25 x Limit Level. 2- As a minimum, the test level shall be equal to or greater than the workmanship level. 3- The sweep direction should be evaluated and chosen to minimize the risk of damage to the hardware. If the sine sweep is used to satisfy the loads or other requirements, rather than to simulate an oscillatory mission environment, a faster sweep rate may be considered, e.g., 6-8 oct/min to reduce the potential for over stress. 4- Normal operating temperature for the LAT is –10° C to 25° C. Survival temperature is –20° C to 40° C. 5-The number of thermal cycles for spares is 8.

76. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem76 Gamma-ray Large Area Space Telescope Fabrication Process Grid Box Assembly Section 13.5

77. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem77 Topics Agenda Procurement plans –Identify critical component need dates vs. delivery dates –Summarize procurement contract status –Long lead part requirement/procurement Fabrication plans –Mech Parts and Materials plan –Material approval status/readiness –M&P Plan, EEE Parts Assembly plans –Grid box assembly sequence –Radiator assembly sequence –X-LAT assembly sequence MGSE Performance and Safety Assurance plans Further Work

78. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem78 Procurement Plans RFP for 4 x 4 Grid & Grid Box Machining –Issue by 4/21/03 –Place contract by 5/15/03 Long Lead Materials –PR for 2 Grid billets is in process now –Lockheed has ordered heat pipe extrusions

79. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem79 Mechanical Parts & Materials Plan Material requirements flow down from the Mission Assurance Requirements 433-MAR-0001 and the Mechanical Parts Plan LAT-SS- 00107-01. LAT Material selection of low outgassing and flight heritage Outgassing specs: TML < 1% CVCM < 0.1% Important Procedures and Guidelines for Material selection Fastener Integrity Requirements (541-PG-8072.1.2) Metallic Materials for Stress Corrosion Cracking Resistance in Sodium Chloride Environment (MSFC-STD-3029) Standard Test Method for Total Mass Loss and Collected Volatile Condensable Materials for Outgassing (ASTM-E-595)

80. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem80 Mechanical Parts & Material: Status Submitted to SLAC IPO as of 3/19/03

81. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem81 M & P Plan, EEE Parts M & P Plan submitted to SLAC (GLS00018-2, dated 1 Feb 2003) EEE Parts –Heaters: Minco Kapton Foil Heaters per GSFC S-311-P-079 –Thermistors: YSI Thermistors per GSFC S-311-P-18 –RTDs: Rosemount PRT per GSFC S-311 –Solid State Thermostats: Micropac 52372”O” Submitted to SLAC for approval Nov 2002

82. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem82 Grid Box Assembly Overview Accepted Hardware Test activity Assembly activity Legend X-LAT Plates Heat Pipe Patch Panels Radiator Mount Bracket Grid Ready for Test Grid Box Base Assy Grid Assy Grid Box Assembly Configuration Grid Box Assy Heat Pipes Purge Groove Cover EMI Skirt Details CAL Plates (Temporary) Spacecraft Interface (Wing)

83. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem83 Grid Assembly The Grid Assembly consists of; 4 x 4 Grid Spacecraft mounting interface (Wing) which is located at the bottom center of each side of the Grid Radiator Mounting Brackets - 2 as shown and 2 opposite. Radiator Mounting Bracket Grid Assembly

84. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem84 Grid Box Base Assembly The Grid Box Base Assembly is the next level assembly, and is the configuration delivered to I&T. It consists of: Grid Assembly Heat Pipe Patch Panels, 2 as shown and 2 opposite Heat Pipes –5 Top Flange Heat Pipes (TFHP) –12 Downspout Heat Pipes (DSHP) 2 Purge groove covers Flight heaters, thermostats & thermistors on Grid Once this assembly is put together, it is not intended to be taken apart. Heat Pipe Patch Panel Grid Box Base Assembly

85. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem85 Grid Box Assembly The Grid Box Assembly is the Mechanical Systems’ top assembly test configuration. It consists of: Grid Box Base Assembly Remaining EMI skirt parts –4 Center EMI Shields –X-EMI Shields, 2 as shown and 2 opposite 2 X-LAT plates with heat pipes X-LAT Mid-plate 16 Temporary Calorimeter plates. Center EMI Shield X-EMI Shield Grid Box Assembly

86. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem86 Grid Fabrication Procure aluminum NDT plate (x-ray, UT, other) Test samples Inspect Grid Clean Grid Finish machine Grid Remove, mach test samples Stress-relieve heat treat Rough machine Grid Procure inserts, mount h’ware Repair as required Install inserts Proof inserts Fabrication activity Inspection/test Assembly activity Legend Grid Inserts Ready for Grid Box Machining Alodine Final Inspection SLAC Buy-off

87. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem87 Grid Box Machining Procure aluminum Procure inserts, mount h’ware Fabrication activity Inspection/test Assembly activity Legend Grid Inserts Deliver To SLAC Machine X-EMI Shields Machine Center EMI Shields Machine Patch Panels Machine Radiator Brkts Clean EMI Skirt Components Inspect Repair as required Install inserts in EMI Skirt Parts Install Radiator Brkts, Patch Panels, Center EMI Shields, & X-EMI Shields on Grid Machine EMI Skirt Co-planer Drill Pin and Bolt Holes in EMI Skirt Parts & Radiator Brkts Machine Radiator mounting surface features in Radiator Brkts Clean Assy Inspect Repair as required EMI Skirt Grid Install inserts in EMI Skirt Parts

88. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem88 Mechanical Systems MGSE

89. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem89 Performance Assurance System Mechanical Systems will comply with the following: –LAT Performance Assurance Implementation Plan (PAIP), LAT-MD-00039 –LAT Quality Manual, LAT-MD-00091 –Configuration Management Plan, LAT-MD-00068 –Instrument Performance Verification Plan, LAT-MD-00408 –Calibration Program, LAT-MD-00470 –System Safety Program Plan (SSPP), LAT-MD-00078 Additionally, above requirements have been flowed down to Suppliers and Subcontractors.

90. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem90 Closure Plans Finalize Wing design Finalize Spacecraft Mount configuration with Spectrum Optimize stress and mass of EMI Skirt components Detail design of assembly MGSE Get Grid vendor under contract

91. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem91 Design, Verification & Fabrication Radiator and X-LAT Assemblies Section 13.6 Brenda Costanzo Lockheed Martin Systems Engineer brenda.costanzo@lmco.com Program Manager: Susan Morrison E-Mail: susan.morrison@lmco.com Gamma-ray Large Area Space Telescope

92. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem92 Responsibility Overview Lockheed Martin hardware responsibilities: –Design, fabrication, and test of the Top Flange Heat Pipes –Design, fabrication, and test of the Downspout Heat Pipes –Design, fabrication, and test of the Radiator Assembly –Design, fabrication, and test of the X-LAT Assembly Additional Lockheed Martin responsibilities: –Thermal analysis for the LAT instrument (covered separately) –LAT thermal systems engineering consultation

93. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem93 Hardware Overview (HPs) Top Flange Heat Pipes (TFHP) –Five constant conductance pipes –Mounted in the +Z surface of the grid –Isothermalize grid –Move energy to DSHPs Down Spout Heat Pipes (DSHP) –Twelve (6 +Y, 6 –Y) constant conductance pipes –Mounted to the +Y and –Y sides of the grid –Move energy from the TFHPs to the radiator heat pipes

94. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem94 Hardware Overview (Radiators) Two radiator panels –Honeycomb core with Aluminum facesheets –Six Variable Conductance Heat Pipes (VCHPs) embedded in each panel –FOSR radiating surface –MLI on non-radiating surfaces –Maintains LAT temperatures –Structural interfaces at the LAT grid and S/C –Thermal interface between radiator VCHPs, X-LAT CCHPs, and downspout CCHPs Radiator Panels Heat Pipe Interface (6 pl/Rad) +Z +Y +X

95. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem95 Hardware Overview (X-LAT Assy) X-LAT Assembly –Two X-LAT plate assemblies 3.2 mm ( 1 / 8 ”) solid Aluminum plate Three Constant Conductance Heat Pipes (CCHPs) per plate –One mid-plate 4.8 mm ( 3 / 16 ”) solid Aluminum plate –Moves heat from electronics to radiators –Load shares between radiator panels Heat Pipe Interface (6 pl/Side) X-LAT Assembly +Z +Y +X

96. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem96 Heat Pipe Sizing All worst case pipe requirements derived from detailed thermal model hot case with the following assumptions and results

97. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem97 Heat Pipe Structural Analysis Top Flange and Downspout Heat Pipes external loads insignificant relative to internal loads due to mounting configuration X-LAT Heat Pipe will be performed once LAT loads are received VC Heat Pipe preliminary analysis covering reservoir and transition complete with the following assumptions and results: –MEOP of 377 PSI (140ºF)**(requirements changed to 490 PSI) –MPP of 882 PSI (210 ºF) –Acceleration loads of 35 G’s replace external flight loads LocationLoading ConditionYieldUltimate FOSM.S.FOSM.S. Reservoir – Inertia WeldMEOP1.53.54.01.0 Reservoir – Inertia WeldMPP1.11.61.251.7 Transition Tube – Orbital WeldMEOP1.56.74.06.2 Transition Tube – Orbital WeldMPP1.13.81.259.5 Transition Tube – Inertia WeldMEOP1.57.04.06.5 Transition Tube – Inertia WeldMPP1.13.71.259.3 Transition Tube – Inertia WeldMEOP + Acceleration1.63.62.08.2

98. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem98 Requirements Basis Radiator requirements based on: –Radiator Level IV Design Specification, LAT-SS-00394-1-D6, draft Dated 5 Mar 2003 –LAT Mechanical Systems Interface Definition Drawing, Radiator- LAT Interface LAT-DS-01221, draft Dated 25 Feb 2003 X-LAT requirements based on: –X-LAT Plate Performance Specification LAT-TD-01240-D3, draft Dated 19 March 2003 –X-LAT Plate Assy Source Control Drawing LAT-DS-01247, draft Dated 7 March 2003 –Mid-Plate Assy Source Control Drawing LAT-DS-01257, draft Dated 7 March 2003

99. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem99 Outer Facesheet VCHPs Honeycomb Core Inner Facesheet Doublers Reservoir Support Bar 1.56 m 1.82 m Radiator Panel, Exploded Z X Y

100. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem100 Radiator Fabrication (1 of 2) Obtain Facesheet Material Shear N/C Machine Inspect Clean, Etch & Prime Bond Pipes To OB Facesheet Inspect Thermal Bond Visual Fit Check Core Machine Transfer Datums Assemble Panel and Bond Verify Cure Profile Process Samples To Lab CMM Inspect Geometry Inspect Holes w/ Pins Prep and Install Inserts & Spools Inspect Inserts & Spools Bond IB Doublers RT Cure Bond OB Doublers AC Cure Verify Cure Profile Inspect Doublers Bond Top Edge Closure Obtain Remaining Flight Materials Inspect Verify Flight Materials Log Flight Materials A Inspection/Test Manufacturing Purchasing

101. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem101 Radiator Fabrication (2 of 2) Notes 1)All panel moves require: inspection documentation of panel for damage; packaging for transport; and flight approved move procedures. 2)No outside storage. 3)Qualified flight transportation personnel and equipment. Apply Edge Closure Tape Inspect Bushings Install Reservoir Bushings Structural Testing Apply Thermal Blanket Apply Blanket Velcro Final Cosmetic Damage Map Thermal Testing Inspect Bushings Fit Check Reservoir Bushings Inspect Reservoir Supports Bond Reservoir Supports Machine Bushings A

102. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem102 Radiator Structural Performance Summary Preliminary analysis indicates the revised Acoustic spectrum produce smaller loads than the assumed dynamic load factor of 30g Positive stress margins obtained for sandwich panel, bolts, inserts and heat pipes Frequency requirement, >50 Hz, satisfied. Design frequency 61.6 Hz Radiator First Five Natural Frequencies Normal Mode 1, f 1 = 61.6 Hz, 1 st YZ Bending Mode

103. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem103 Radiator Thermal Performance Summary Q max = 602 W Q min = 475 W Requirement: T max RIT <15 °C Q avg Reservoir < 48 W –Predictions T max RIT = 10 °C T maxRIT = 14 °C, 1 HP failed Q avg Reservoir = 13 W Requirement: T min RIT >-10 °C Q avg Reservoir < 48 W –Predictions T min RIT = -5 °C Q avg Reservoir = 13 W Requirement: T min RIT >-20 °C, Survival Q avg Reservoir < TBD W –Predictions T min RIT = -20 °C Q avg Reservoir = 42 W Cold RIT Temperatures

104. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem104 Requirement Compliance (Radiator) The following table addresses key requirements that are not yet defined or compliance is in question

105. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem105 Radiator Compliance Mitigation Plans (1 of 2) Mass –Primary mitigation step is for SLAC to increase the radiator mass allotment if necessary –If mass allotment is exceeded, can reduce thickness of honeycomb core Impact to structural design margin CG in Z-direction –Expected mitigation is to change requirement to CG located no less than 720 mm from datum –If requirement change is not incorporated, can add weights to –Z edge of radiator panel Impact to structural design margin Impact to mass Dynamic envelope –Received e-mail change to dynamic envelope, waiting incorporation into spec. –If change is not incorporated, can reduce thickness of honeycomb core Impact to structural design margin

106. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem106 Radiator Compliance Mitigation Plans (2 of 2) Static envelope –Currently working with SLAC to increase localized static envelope –If envelope can not be increased, can do all or some of the following: Reduce thickness of honeycomb core –Impact to structural design margin Remove MLI from back side of VCHP reservoirs –Impact to heater power –Impact to VCHP performance Remove option of repinching VCHPs –Increase cost risk Power allocations –SLAC power allocations should reflect current design predictions, with appropriate margin –If power can not be allocated, can do all or some of the following Decrease radiator size –Impact to hot case LAT temperatures

107. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem107 X-LAT Design CCHPs are bonded and riveted to X-LAT plates X-LAT plates are interchangeable Material is 0.125” 6061 Aluminum Radiator Bracket Alignment Pin Hole X-LAT Plate Interface to Mid-Plate CCHP (3 pl) Push-Pull Bolt Interface Hole (24 pl, TBR) X-LAT Plate Assy (2x) Interface To X-LAT Plate (both sides) Push-Pull Bolt Interface Hole (12 pl, TBR) Mid- Plate (1x)

108. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem108 X-LAT Structural Performance Summary Model was simply supported at the edges, and constrained in the Z direction only at each of the spacer locations Frequency Requirement, > 50 Hz –Analysis: First mode = 97.7 hz Loads –Highest load on plate is random vibration –Calculate 3  random vibration load factor in g using Miles’ equation => 3*sqrt((  /2)*PSD*Q*f)), where: PSD at first resonant frequency is 0.08 g**2/Hz (source – LAT-TD- 01240) Q = 50 (1% damping) F = 97.7 Hz Load cases run –74.4 g acceleration normal to plate –74.4 g g lateral in plane of plate Load CaseStress (KSI) Yield Safety Margin Ultimate Safety Margin 1: 74.4 g Normal Load 11.2+1.92+1.68 2: 74.4 g In- Plane Load.32+101.+93. Stress for 74.4 g normal load

109. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem109 X-LAT Thermal Performance Summary Q max = 359.9 W Q min = 286.2 W Requirement: T max <35 °C –Predictions T max = 24.2 °C Requirement: T min >-10 °C Q avg Reservoir < 48 W –Predictions T min RIT = -5 °C Note: Not identified are the 16 TEM/TPS stacks X Y 17.3 °C 20.3 °C EPU 22.6 °C PDU 20.4 °C 17.3 °C 20.3 °C EPU GASU SIU 24.2 °C 19.4 °C 20.1 °C 22.3 °C21.3 °C Comb

110. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem110 Requirement Compliance (X-LAT) The following table addresses key requirements that are not yet defined

111. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem111 X-LAT Compliance Mitigation Plans Must define/finalize requirements and determine if there’s a non- compliance. If there is, the following plan will be activated: –Temperature Limits and Electronics Power Values Increase conduction from the X-LAT to the warm electronic(s) If there is still a problem, increase the thickness of the X-LAT panel(s) –Impact on structural and mass margins –Envelope Increase dynamic envelope to accommodate dynamic motion If dynamic envelope can not be changed, increase panel thicknesses –Impact on thermal, structural, and mass margins –Loads Adjust panel thicknesses –Impact on thermal, structural, and mass margins

112. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem112 Test plan is document GLS0002-03 All testing will have procedures written prior to commencement Inspection occurs throughout the testing at points specified in the procedure Flash reports will be written within 3 working days of test completion Full reports will be written within 30 days of test completion or by pre-ship review, whichever is earlier Radiator and X-LAT Verification Heat Pipe In-Process Tests X-LAT Assy Acceptance Tests Integrated Radiator & X- LAT Assy Thermal Test Delivery In- Place to SLAC Heat Pipe Acceptance Tests X-LAT In-Process Tests VCHPs Only X-LAT CCHPs Only Radiator Acceptance Tests Radiator In-Process Tests TCS Thermal Test (TBR) Deliver to SLAC

113. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem113 Structural and EMI Verification Each radiator panel tested individually Tested at the X-LAT Assembly level Radiator Vibration Testing Pre- Vibration IR Signature Low Level Sine Survey Sine Vibration Limit Load Test Acoustic Vibration Post- Vibration IR Signature Low Level Sine Survey Mass Properties X-LAT/Radiator Assy Thermal Testing Radiated Emissions Conducted Emissions Radiated Susceptibility Conducted Susceptibility Radiator EMI Testing (TBR) X-LAT Vibration Testing Low Level Sine Survey Sine Vibration (TBR) Static Load Test Acoustic Vibration (TBR) Low Level Sine Survey Mass Properties Random Vibration (TBR) Deliver to SLAC

114. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem114 Radiator & X-LAT Assy Thermal Testing (1 of 2) Hardware configuration –X-LAT Assy –Radiator Assy –Heater plate to introduce heat into the system –Lab electronics to control VCHPs Hardware orientation –+X side up –Level within 0.10” +X +Y Gravity is Down Cold Wall Flight Radiators (2) MLI Blanket NO SCALE X-LAT Assy

115. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem115 Radiator & X-LAT Assy Thermal Testing (2 of 2) Pre-Cycling Functional Test Pump Down Chamber Thermal Cycle 1 Bakeout / Hot Survival Hot Temperature Turn-On Cold Survival Cold Temperature Turn-On Thermal Cycle 3 Cold Balance Point Thermal Cycle 2 Hot Balance Point Post-Cycling Functional Test Delivery In- Place to SLAC TCS Thermal Testing (TBR) IR Signature Hot Balance Point Cold Portion of Thermal Cycle Thermal Cycle 4

116. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem116 TCS Thermal Testing Hardware Configuration –Radiator Assy –X-LAT Assy –Downspout heat pipes (TBR) –LAT mass simulator Test Objective –Verify VCHP reservoir heater operational algorithm Test Flow Bakeout / Hot Survival Hot Temperature Turn-On Pre-Cycling Functional Test Pump Down Chamber Cold Balance Point Hot Balance Point Post-Cycling Functional Test Cold Survival Cold Temperature Turn-On Hot Balance Point Cold Temperature Turn-Off Repressurize Chamber

117. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem117 Radiator/X-LAT Risk Summary ID #Risk Rank Risk DescriptionRisk MitigationMitigation Status 1High Specifications, IDDs, and SCDs are unreleased. Draft documents have many TBDs and TBRs Higher level changes are not formally flowed down. Changes are given to various LM personnel. Incorrect hardware may be built Delays in document finalization may impact cost & schedule All radiator and X-LAT control documents to be released. (5/12/03) Identify SLAC person responsible for flow down of requirements (5/12/03) Changes to documents to be sent through contracts (May 03 and beyond) Review of control documents performed by all SLAC stake- holders (May 03 and beyond) On track

118. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem118 Further Work Design –Review finalized control documents to assess impacts to requirements compliance, cost, and schedule –Resolve any non-compliances Fabrication –Begin writing shop orders –Complete fixture design and manufacture Test –Complete development tests Heat Pipe bend Insert pull tests (radiator) Push-pull bolt lateral slip testing (X-LAT) –Negotiate contract terms to allow joint thermal testing of radiator and X-LAT assemblies –Determine need for TCS thermal testing

119. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem119 Gamma-ray Large Area Space Telescope Cost and Schedule Section 13.7

120. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem120 CCB Actions Affecting 4.1.8 Change Request #DescriptionStatus LAT-XR-01149-01Lockheed Martin Contract Rebaseline Approved, $56K LAT-XR-01159-01Procurements Move from FY04 to FY03 Approved, $0K LAT-XR-01585-01Transfer to 4.1.1.5 Instrument Design Engineering Approved, -$1.4M LAT-XR-1621-01Mass Allocation Increase Approved, 22 kg

121. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem121 4.1.8 Work Flow Summary X-LAT PLATES X-LAT PLATES & RADIATORS GRID BOX RFI 23MAR04

122. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem122 Key Deliverable Milestones Product Available Date Integration Need Date Forecast Baseline Forecast Baseline

123. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem123 Critical Path

124. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem124 Budget, Cost, Performance

125. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem125 Cost/Schedule Status ItemIn k$ Budget at Complete11,794 Budgeted Cost for Work Scheduled (a)4,603 Budgeted Cost for Work Performed (b)3,939 Actual Cost for Work Performed3,543 Cost Variance395 10% of (b) Schedule Variance-664-14% of (a) Status as of February 28, 2003:

126. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem126 Resource Scheduling by FY

127. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem127 Procurements Long-Lead Procurements –Aluminum Billets –Heat pipe extrusions (LM) –Solid State thermostats (LM) Major Upcoming Procurements Near-Term (< 4 months) –Lockheed Martin Phase 2 –Grid Assembly –Flight Hardware for Control System Major Upcoming Procurements Long-Term (>4 months) –GSE Minor Upcoming Procurements –Grid Assembly Fixtures, Test Equipment –Thermal-vac Test Fixtures

128. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem128 Gamma-ray Large Area Space Telescope Risk and Summary Section 13.8

129. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem129 Risk Summary ID #Risk RankRisk DescriptionRisk Mitigation Mech 0001 Mech 306 High X-LAT plate to Electronics box thermal joint does not perform as designed 1) Clarity interface responsibilities and requirements -complete 2) Detail interface options -complete 3) Complete interface analysis – prelim. Complete (Wang) 4) Prototype interface techniques (Lam ) 5) Complete detail box thermal analysis (Haller) 6) Select Design approach (Campell) 7) Complete integrated analysis (Wang) 8) Complete EM Test (Lam) Mech 0002 Mech 307 Very Low Radiator VCHP to Downspout and X-LAT heat pipes thermal joint fails during thermal vac test 1) Prototype verification test (ECD-July 03) 2) Develop process control requirements (ECD-Aug 03)

130. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem130 ID #Risk Rank Risk DescriptionRisk Mitigation Mech 0003 Mech 308 Low CAL to Grid friction joint does not perform as designed. The critical joint properties (coefficient of friction and bolt clamping force) can not be directly verified before or after environmental test EM testing of joint and FE model verification. Maintain large design margins for joint load capability 1) EM Test completed 2) FE Model Verification 3) Independent analysis complete Mech 0004 Mech 321 Low Maturing spacecraft design may result in late changes in Instrument/SC interfaces; resulting in LAT design changes past I-CDR and associated cost; schedule impact Identify priority of detailed I/T design tasks with Spectrum via ongoing working groups (1) Identify key I/F's driving detailed design by Peer Review 26 March. (2) Complete final Interface drawings by 28 March to support final S/C-LAT ICD release. (3) Finalize CG and document of internal agreements 28 March. (4) Develop and agree upon closure plan with Spectrum for all issue identified in (1), LAT CDR (28 April Risk Summary

131. GLAST LAT ProjectCDR/CD3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Subsystem131 ID #Risk RankRisk DescriptionRisk Mitigation Mech 0005 Mech 323 Low Availability of Grid and ACD-BEA for match drilling at mutually acceptable timeframes Establish multiple windows of opportunity to do the operation and or additional tooling 1) Develop schedule window work-arounds (ECD – June 03) 2) Evaluate creating drill template to remove schedule dependency (ECD-June 03) Mech 0006 Mech 541 Moderate Repeatable X-LAT Thermal Joint performance X-LAT plates are removed to service electronics boxes X-LAT plates could be removed after LAT or Observatory thermal testing Same as Mech 0001 Mech 0007 Mech 542 Moderate Repeatable Radiator Thermal Joint Performance “Wet” joint is disassembled & re-assemble after LAT thermal balance test 6 joints per radiator must be made within pot life of thermal adhesive 1) Same as Mech 0002 Risk Summary