GLAST LAT Project Gamma-ray Large Area Space Telescope

GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD 3 Review May 12 -16, 2003 GLAST Large Area Telescope: Mechanical Systems WBS: 4. 1. 8 Section 13 Marc Campell SLAC Mechanical Systems Manager marcc@slac. stanford. edu Document: LAT-PR-01967 Section 13 Mechanical Subsystem 1

GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD 3 Review May 12 -16, 2003 Overview Section 13. 1 Section 13 Mechanical Subsystem 2

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Mechanical Systems Organization Document: LAT-PR-01967 Section 13 Mechanical Subsystem 3

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Mechanical Subsystems Overview Grid Assembly +Z Grid Box Assembly Mid-Plate X-LAT Plate Assy +Z SC “wings” Radiator Mount Bracket EMI Shields Document: LAT-PR-01967 Section 13 Mechanical Subsystem 4

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Radiator Placement +Z Document: LAT-PR-01967 +Z Section 13 Mechanical Subsystem 5

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 6

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Design & Fabrication Responsibilities Manufacturing/Integration Activity Grid Assembly Fabricate, inspect Grid structure Fabricate, test Top Flange heat pipes Fabricate, test Downspout heat pipes Assemble, test Grid assembly Fabricate, inspect EMI Skirt parts X-LAT Thermal Plate Fabricate, inspect X-LAT Plate parts Fabricate, test X-LAT heat pipes Assemble, test X-LAT Thermal Plates Assemble, test mid-plate Radiators Quantity Flt/Spare Responsible Work Organization Performed 1/0 5/1 12 / 1 1/0 SLAC LM-ATC SLAC Sub LM-HPPC SLAC 9/1 2/1 1/0 LM-ATC LM LM-HPPC LM-ATC Sub Fabricate, inspect Radiator parts Fabricate, test Radiator VC heat pipes 12 / 1 LM-ATC LM-HPPC Assemble, inspect Radiators 2/0 LM-ATC LM-HPPC LM-ATC SLAC LM-ATC Sub LM-ATC Test Radiators Thermal Control System Fabricate TCS hardware Thermal-balance test TCS system 1/1 1/0 Mechanical Systems Legend LM-ATC LMHPPC SLAC Sub Lockheed-Martin Advanced Technology Center, Palo Alto CA Lockheed-Martin Heat Pipe Product Center, Sunnyvale CA Stanford Linear Accelerator Center, Menlo Park CA Subcontractor to be determined Document: LAT-PR-01967 Section 13 Mechanical Subsystem 7

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Design Problem Areas • CAL-GRID Interface • Electronics-Box to X-LAT Interface Document: LAT-PR-01967 Section 13 Mechanical Subsystem 8

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 CAL-GRID Interface Design Problem Status • At PDR & d. PDR 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 analyzed. Document: LAT-PR-01967 Section 13 Mechanical Subsystem 9

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 10

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 X-LAT to Electronics-Box Thermal Joint Design Problem Status • At PDR & d. PDR 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 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 XLAT plate removal for Electronics box access Document: LAT-PR-01967 Section 13 Mechanical Subsystem 11

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 12

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 13

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 14

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 15

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 RFA Response ID # Status 1 RFA Description RFA Response/Closure Plan Open/Closed 10 12 27 28 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 16

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 RFA Response ID # Status 29 RFA Description RFA Response/Closure Plan Open/Closed 32 33 34 36 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 17

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 RFA Response ID # Status 37 RFA Description RFA Response/Closure Plan Open/Closed 38 39 40 41 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 18

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 RFA Response ID # Status 42 RFA Description RFA Response/Closure Plan Open/Closed 43 45 46 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 19

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 20

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Summary • Mechanical Systems detailed design and analysis indicates that all requirements will be met. • Mechanical Systems has accommodated changes since d. PDR. • 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 ICDR. • 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. Document: LAT-PR-01967 Section 13 Mechanical Subsystem 21

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 22

GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD 3 Review May 12 -16, 2003 Requirements Section 13. 2 Section 13 Mechanical Subsystem 23

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 24

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Mechanical Subsystem Mass Budget Document: LAT-PR-01967 Section 13 Mechanical Subsystem 25

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Mechanical Systems Power Budget Operational Mode Power Allocation, W Nominal Operation Survival 35 220 Document: LAT-PR-01967 Estimate, W 20. 4 152. 0 Section 13 Mechanical Subsystem 26

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

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Key Mechanical Systems Requirements (1 of 2) Sect Requirement 8 Configuration 8. 1. Mass The total mass of Mechanical Systems <345 kg Design Margin Comply Method Req. Source 15. 7 Y I LAT-TD-00125 -1 >1. 89 m 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 <220 W @ 27 V min 152. 0 68(45%) Y D IRD 3. 2. 4. 1. 7. 6 (Derived) When off, peak survival heater power < 560 W 8. 3. 329. 3 Ok 387 W@ 35 V (incl 30% Control margin) Y T, A IRD 3. 2. 4. 1. 7. 6 (Derived) Y T IRD 3. 2. 2. 8. 1. 2 Y T, A IRD 3. 2. 2. 8. 1. 2 Stay-Clear Volume and Dimensions Radiator positioned according to IRD Appendix A 8. 5. 8. 6. Stiffness Fixed-base first-mode > 50 Hz Provisions for Integration and Test During Obs T-Vac, TCS capable of full functionality “lying on its side” Document: LAT-PR-01967 55. 5 Hz Ok 11% Section 13 Mechanical Subsystem 28

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Key Mechanical Systems Requirements (2 of 2) Sect Requirement 9 LAT Alignment 9. 1. Alignment Stability Maintain TKR alignments to < 7 arc-seconds, 1 s radial, during normal LAT operation Design Margin Comply Method Req. Source 4. 1 arc-sec Peak to-Peak Y T, A MSS 3. 3. 1. 1. 2 Ok Y T, A IRD 3. 2. 2. 8. 2 Y A IRD 3. 2. 2. 8. 2 11 Capable of withstanding static loads in thrust and lateral Ok simultaneously Thermal Environment and Heat Loads 11. 1. Process and Interface Heat Loads Y T, A IRD 3. 2. 4. 1. 1 Y T, A IRD 3. 2. 3. 4. 5 Y T, A MSS 3. 3. 2. 3 (Derived) IRD 3. 2. 3. 5 (Derived) 10 2. 9 arc-sec +5 s Structural Load Environment 10. 1. Structural Loads Capable of exposure to static launch loads Maximum process power indefinite dissipation 612 W LAT+ 38 W Rad @ 24 deg C 5 deg. C calc+ 1 deg C operating Capable of normal operation when loaded by 75 W/Rad 73. 4 W/Rad 0 W/Rad From SC solar arrays 11. 3. Environment Heat Loading and Orbital Parameters Provide thermal control with LAT pointed 2 pi/24/7/365 during any normal LAT mode Capable of maintaining thermal control during exposure to IR, Albedo, Solar fluxes Document: LAT-PR-01967 Section 13 Mechanical Subsystem 29

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 30

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Driving Design Requirements (Radiator: Mechanical) Document: LAT-PR-01967 Section 13 Mechanical Subsystem 31

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Driving Design Requirements (Radiator: Structural) Document: LAT-PR-01967 Section 13 Mechanical Subsystem 32

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Driving Design Requirements (Radiator: Thermal) Document: LAT-PR-01967 Section 13 Mechanical Subsystem 33

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Driving Design Requirements (X-LAT) Document: LAT-PR-01967 Section 13 Mechanical Subsystem 34

GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD 3 Review May 12 -16, 2003 Design Grid Box Assembly Section 13. 3 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 35

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Drawing Tree Document: LAT-PR-01967 Section 13 Mechanical Subsystem 36

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Grid Box Assembly Design +Z CAL-Grid Interface Mid-Plate X-LAT Plate Assy +Z Radiator Mount Bracket Heat Pipe Patch Panel EMI Shields S/C Mount Interface Document: LAT-PR-01967 Section 13 Mechanical Subsystem 37

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 T 6 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 N 2 purging of the CAL’s during ground operations Document: LAT-PR-01967 Section 13 Mechanical Subsystem 38

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Grid Structure Helicoils for CAL bolts Top Flange Heat Pipes +Z Purge grooves +Z Document: LAT-PR-01967 Section 13 Mechanical Subsystem 39

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 cutouts 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 40

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 41

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Electronics Stack Cross-Section • 4 cm wide Vel-Therm strip placed around perimeter of each box optimizes conduction vs contact pressure required Midplate to X-LAT Thermal Joint, 2 PLCS, Approx. 60 #6 Fasteners each side Vel-Therm X-LAT Plate Midplate Bolting X-LAT Plate to EMI Shields, Approx. 60 #8 Fasteners per Plate X-LAT Plate EMI Shields GRID Note: View along Y-axis Document: LAT-PR-01967 Section 13 Mechanical Subsystem 42

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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, XLAT and Radiator HP’s • Supports X-LAT plates • Provides mounting for Connecter Patch Plates from Electronics • Provides for venting of enclosure Construction • 6061 -T 6 AL machining, alodine • Pieces bolted to Grid & each other Document: LAT-PR-01967 Section 13 Mechanical Subsystem 43 +Z

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 -T 6 Al machining, alodine • Bolts to 3 orthogonal surfaces of Grid corner Document: LAT-PR-01967 Section 13 Mechanical Subsystem 44

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 -T 6 machining, alodine • Bolted, pinned & keyed to Grid +Z Document: LAT-PR-01967 Section 13 Mechanical Subsystem 45

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 46

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Stress Analysis Topics • Cal-Grid interface load recovery • Grid Stress analysis • Radiator Mount Bracket analysis • Summary and Closure Plan Document: LAT-PR-01967 Section 13 Mechanical Subsystem 47

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Histogram Showing Required Friction Coefficients Qual Friction Coefficients for CAL-Grid Joint Section 13 Mechanical Subsystem 48

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 -T 6 aluminum (6061 -T 651, stress-relieved, then heattreated during fabrication) – Sy = 240 MPa (35 ksi) – Su = 290 MPa (42 ksi) Factors of safety (per NASA-STD-5001) – Metallic structures • Yield: FSy = 1. 25 • Ultimate: FSu = 1. 4 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 49

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 CASE +X/-Z -X/-Z +Y/-Z -Y/-Z LIFT X [N] 994 -994 0 0 0 Y [N] 0 0 333 -333 0 Z [N] -1670 32400 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 50

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Summary and Closure Plan • Summary – Integrated LAT structural analysis results of the staticequivalent 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 51

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Grid/Grid Box Assembly Verification Topics • 4 x 4 Grid Verification • Grid Box Assembly Verification Document: LAT-PR-01967 Section 13 Mechanical Subsystem 52

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 4 x 4 Grid Structure Verification Mass Properties & C. G. Verified Document: LAT-PR-01967 Dimension Check Verified Proof Test of Inserts Section 13 Mechanical Subsystem 53

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 54

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 55

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Grid - Flight Radiator Mount Brackets - 4 X Flight EMI Skirts - Flight Calorimeter Plates -16 X Flight-like Down spout HPs - 12 X - Flight Spacecraft Mount Brackets - 4 X - Flight XLAT Plate - Flight Document: LAT-PR-01967 Section 13 Mechanical Subsystem 56

GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD 3 Review May 12 -16, 2003 Verification Program Grid Box Assembly Section 13. 4 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 57

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 58

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 EM Test Plans Overview • EM test plans developed for: – CAL-Grid Joint Testing • Friction characterization • Bolt-Helicoil pair characterization • Pull tab coupons – 1 x 4 Grid – Grid heat pipe bonding process qualification – Joint candidates • “Wet” adhesive or gasket • Low contact pressure • No contact pressure – X-LAT heat pipe characterization Document: LAT-PR-01967 Section 13 Mechanical Subsystem 59

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 60

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 61

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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) Document: LAT-PR-01967 Section 13 Mechanical Subsystem 62

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 63

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 64

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Joint Candidates Tested • “Wet” adhesive or gasket joints – Thermally conductive silicone adhesive, Nusil CV 2946 – Sil. Pad, VO Gap Pad • Low contact pressure joints – Off-the-shelf EMI gasket products, i. e. Be. Cu 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) Document: LAT-PR-01967 Section 13 Mechanical Subsystem 65

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 66

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 67

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 68

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 69

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Heatpipe Characterization Test Setup Cold Zone 2 Chilled Water Source Heat Zone 4 Heat Zone 3 Heat Zone 2 Heat Zone 1 Cold Zone 1 CCHP Heatpipe Chamber Document: LAT-PR-01967 Tilt Meter Close-up of Cold Zone Section 13 Mechanical Subsystem 70

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 EM Closure Plan Summary Document: LAT-PR-01967 Section 13 Mechanical Subsystem 71

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 72

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Mechanical Systems Verification Test Flow Grid Structure -Proof Load -Mass Properties & C. G. -Dimension Check Radiator Mount Bracket X-LAT Plates Grid Box Base Assembly Disassemble Grid Box Base Assembly Grid Box Assembly -Static Load -Thermal Cycle -Mass Properties & C. G. -Dimension Check -Alignment -Functional -Static Load Test -Mass Properties & C. G. -Dimension Check -Thermal Vacuum Test Grid Assembly LAT Integration X-LAT Plates Mid-Plate X-LAT Plates -Static Load Test -Mass Properties & C. G. -Dimension Check Radiator -Sine Sweep -Acoustic -Mass Properties & C. G. -Dimension Check -Interface Verification -EMI/EMC -Functional Document: LAT-PR-01967 Assemble Radiator pair test configuration Radiators LAT Level Verification Tests -Thermal Balance -Mass Properties & C. G. -Dimension Check Section 13 Mechanical Subsystem 73

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Mechanical Subsystem Verification Matrix LEGEND Assembly Level S – Subsystem A- Assembly C – Component Unit Type PF – Proto Flight F – Flight S – Spare Document: LAT-PR-01967 Q – Qual E – Engineering Model V – Verification Model Verification Method T – Test TQ – Test, Qualification Level A –Analysis TA – Test, Acceptance Level M – Measurement P – Proof I – Inspection Section 13 Mechanical Subsystem 74

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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. Document: LAT-PR-01967 Section 13 Mechanical Subsystem 75

GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD 3 Review May 12 -16, 2003 Fabrication Process Grid Box Assembly Section 13. 5 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 76

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 77

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 78

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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) Document: LAT-PR-01967 Section 13 Mechanical Subsystem 79

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Mechanical Parts & Material: Status • Submitted to SLAC IPO as of 3/19/03 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 80

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 M & P Plan, EEE Parts • M & P Plan submitted to SLAC (GLS 00018 -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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 81

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Grid Box Assembly Overview Grid Assy Grid Box Base Assy Grid Box Assy Ready for Test Radiator Mount Bracket Spacecraft Interface (Wing) EMI Skirt Details Heat Pipe Patch Panels X-LAT Plates Heat Pipes Purge Groove Cover Legend Accepted Hardware CAL Plates (Temporary) Grid Box Assembly Configuration Test activity Assembly activity Document: LAT-PR-01967 Section 13 Mechanical Subsystem 82

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Grid Assembly Section 13 Mechanical Subsystem 83

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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. Grid Box Base Assembly Heat Pipe Patch Panel Document: LAT-PR-01967 Section 13 Mechanical Subsystem 84

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Grid Box Assembly • 2 X-LAT plates with heat pipes • X-LAT Mid-plate • 16 Temporary Calorimeter plates. Center EMI Shield Document: LAT-PR-01967 X-EMI Shield Section 13 Mechanical Subsystem 85

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Grid Fabrication Grid Procure aluminum NDT plate (x-ray, UT, other) Rough machine Grid Stress-relieve heat treat Finish machine Grid Remove, mach test samples Test samples Clean Grid Inspect Grid Inserts Procure inserts, mount h’ware Repair as required Alodine Install inserts Proof inserts Ready for Grid Box Machining SLAC Buy-off Final Inspection Legend Fabrication activity Inspection/test Assembly activity Document: LAT-PR-01967 Section 13 Mechanical Subsystem 86

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Grid Box Machining EMI Skirt Grid Procure aluminum Grid Machine Radiator Brkts Machine Patch Panels Clean EMI Skirt Components Inserts Procure inserts, mount h’ware Machine Center EMI Shields Machine X-EMI Shields Install inserts in EMI Skirt Parts Inspect Repair as required Install Radiator Brkts, Patch Panels, Center EMI Shields, & X-EMI Shields on Grid Repair as required Inspect Clean Assy Drill Pin and Bolt Holes in EMI Skirt Parts & Radiator Brkts Machine Radiator mounting surface features in Radiator Brkts Machine EMI Skirt Co-planer Legend Install inserts in EMI Skirt Parts Deliver To SLAC Fabrication activity Inspection/test Assembly activity Document: LAT-PR-01967 Section 13 Mechanical Subsystem 87

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Mechanical Systems MGSE Document: LAT-PR-01967 Section 13 Mechanical Subsystem 88

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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. Document: LAT-PR-01967 Section 13 Mechanical Subsystem 89

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 90

GLAST LAT Project Gamma-ray Large Area Space Telescope CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 91

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 92

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 93

• GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Heat Pipe downspout CCHPs Interface (6 pl/Rad) Document: LAT-PR-01967 +Z +Y +X Radiator Panels Section 13 Mechanical Subsystem 94

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Heat Pipe radiator panels Interface (6 pl/Side) X-LAT Assembly +Z +Y +X Document: LAT-PR-01967 Section 13 Mechanical Subsystem 95

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Heat Pipe Sizing • All worst case pipe requirements derived from detailed thermal model hot case with the following assumptions and results Document: LAT-PR-01967 Section 13 Mechanical Subsystem 96

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Location Loading Condition Yield Ultimate FOS M. S. Reservoir – Inertia Weld MEOP 1. 5 3. 5 4. 0 1. 0 Reservoir – Inertia Weld MPP 1. 1 1. 6 1. 25 1. 7 Transition Tube – Orbital Weld MEOP 1. 5 6. 7 4. 0 6. 2 Transition Tube – Orbital Weld MPP 1. 1 3. 8 1. 25 9. 5 Transition Tube – Inertia Weld MEOP 1. 5 7. 0 4. 0 6. 5 Transition Tube – Inertia Weld MPP 1. 1 3. 7 1. 25 9. 3 Transition Tube – Inertia Weld MEOP + Acceleration 1. 6 3. 6 2. 0 8. 2 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 97

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Requirements Basis • Radiator requirements based on: – Radiator Level IV Design Specification, • LAT-SS-00394 -1 -D 6, 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 -D 3, 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 98

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Radiator Panel, Exploded Outer Facesheet VCHPs Doublers Honeycomb Core 1. 56 m Inner Facesheet Z X Y Reservoir Support Bar 1. 82 m Document: LAT-PR-01967 Section 13 Mechanical Subsystem 99

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Radiator Fabrication (1 of 2) Obtain Facesheet Material Shear Obtain Remaining Flight Materials Bond Pipes To OB Facesheet N/C Machine Log Flight Materials Inspect Thermal Bond Visual Process Samples To Lab CMM Inspect Geometry Inspect Doublers Document: LAT-PR-01967 Bond OB Doublers AC Cure Inspect Purchasing Clean, Etch & Prime Inspection/Test Manufacturing Inspect Verify Flight Materials Fit Check Core Inspect Holes w/ Pins Verify Cure Profile Assemble Panel and Bond Verify Cure Profile Prep and Install Inserts & Spools Bond Top Edge Closure Inspect Inserts & Spools Machine Transfer Datums Bond IB Doublers RT Cure A Section 13 Mechanical Subsystem 100

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Radiator Fabrication (2 of 2) A Bond Reservoir Supports Install Reservoir Bushings Fit Check Reservoir Bushings Inspect Reservoir Supports Inspect Bushings Apply Blanket Velcro Machine Bushings Apply Edge Closure Tape Apply Thermal Blanket Inspect Bushings Structural Testing Final Cosmetic Damage Map Thermal Testing 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. Document: LAT-PR-01967 Section 13 Mechanical Subsystem 101

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Radiator Structural Performance Summary • • • Preliminary analysis indicates the revised Acoustic spectrum produce smaller loads than the assumed dynamic load factor of 30 g 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 Document: LAT-PR-01967 Normal Mode 1, f 1 = 61. 6 Hz, 1 st YZ Bending Mode Section 13 Mechanical Subsystem 102

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Radiator Thermal Performance Summary • • • Qmax = 602 W Qmin = 475 W Requirement: Tmax RIT <15 °C Qavg Reservoir < 48 W – Predictions • Tmax RIT = 10 °C • T max. RIT = 14 °C, 1 HP failed • Qavg Reservoir = 13 W Requirement: Tmin RIT >-10 °C Qavg Reservoir < 48 W – Predictions • Tmin RIT = -5 °C • Qavg Reservoir = 13 W Requirement: Tmin RIT >-20 °C, Survival Qavg Reservoir < TBD W – Predictions • Tmin RIT = -20 °C • Qavg Reservoir = 42 W Document: LAT-PR-01967 Cold RIT Temperatures Section 13 Mechanical Subsystem 103

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Requirement Compliance (Radiator) • The following table addresses key requirements that are not yet defined or compliance is in question Document: LAT-PR-01967 Section 13 Mechanical Subsystem 104

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 105

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 106

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 X-LAT Design • • • CCHPs are bonded and riveted to X-LAT plates are interchangeable Material is 0. 125” 6061 Aluminum X-LAT Plate Assy (2 x) CCHP (3 pl) Mid- Plate (1 x) Push-Pull Bolt Interface Hole (12 pl, TBR) Push-Pull Bolt Interface Hole (24 pl, TBR) X-LAT Plate Interface to Mid-Plate Interface To X-LAT Plate (both sides) Radiator Bracket Alignment Pin Hole Document: LAT-PR-01967 Section 13 Mechanical Subsystem 107

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 s random vibration load factor in g using Miles’ equation => 3*sqrt((p/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 Document: LAT-PR-01967 Load Case Stress (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 Section 13 Mechanical Subsystem 108

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 X-LAT Thermal Performance Summary 17. 3 °C EPU PDU 20. 3 °C 20. 4 °C Comb 22. 6 °C 20. 3 °C 24. 2 °C GASU 22. 3 °C 21. 3 °C Comb • 17. 3 °C Comb • Qmax = 359. 9 W Qmin = 286. 2 W Requirement: Tmax <35 °C – Predictions • Tmax = 24. 2 °C Requirement: Tmin >-10 °C Qavg Reservoir < 48 W – Predictions • Tmin RIT = -5 °C Note: Not identified are the 16 TEM/TPS stacks Comb • • • 19. 4 °C EPU SIU 20. 1 °C Y X Document: LAT-PR-01967 Section 13 Mechanical Subsystem 109

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Requirement Compliance (X-LAT) • The following table addresses key requirements that are not yet defined Document: LAT-PR-01967 Section 13 Mechanical Subsystem 110

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 X-LAT Compliance Mitigation Plans • Must define/finalize requirements and determine if there’s a noncompliance. 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 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 111

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Radiator and X-LAT Verification • Test plan is document GLS 0002 -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 In-Process Tests Radiator Acceptance Tests VCHPs Only Heat Pipe In-Process Tests Heat Pipe Acceptance Tests X-LAT CCHPs Only X-LAT In-Process Tests Document: LAT-PR-01967 Integrated Radiator & XLAT Assy Thermal Test X-LAT Assy Acceptance Tests Delivery In. Place to SLAC TCS Thermal Test (TBR) Deliver to SLAC Section 13 Mechanical Subsystem 112

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Structural and EMI Verification • Each radiator panel tested individually Radiator Vibration Testing Pre. Vibration IR Signature Low Level Sine Survey Acoustic Vibration Sine Vibration Limit Load Test Post. Vibration IR Signature Radiator EMI Testing (TBR) Mass Properties Radiated Emissions Conducted Emissions Radiated Susceptibility Conducted Susceptibility X-LAT/Radiator Assy Thermal Testing • Tested at the X-LAT Assembly level X-LAT Vibration Testing Low Level Sine Survey Static Load Test Random Vibration (TBR) Document: LAT-PR-01967 Sine Vibration (TBR) Acoustic Vibration (TBR) Low Level Sine Survey Mass Properties Deliver to SLAC Section 13 Mechanical Subsystem 113

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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” NO SCALE Flight Radiators (2) X-LAT Assy Cold Wall +X MLI Blanket +Y Document: LAT-PR-01967 Gravity is Down Section 13 Mechanical Subsystem 114

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

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Pump Down Chamber Pre-Cycling Functional Test Hot Balance Point Cold Balance Point Document: LAT-PR-01967 Bakeout / Hot Survival Cold Temperature Turn-Off Hot Balance Point Hot Temperature Turn-On Cold Survival Post-Cycling Functional Test Cold Temperature Turn-On Repressurize Chamber Section 13 Mechanical Subsystem 116

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Radiator/X-LAT Risk Summary ID # Risk Rank Risk Description • Specifications, IDDs, and SCDs are unreleased. • Draft documents have many TBDs and TBRs 1 High • 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 Document: LAT-PR-01967 Risk Mitigation • All radiator and X-LAT control documents to be released. (5/12/03) Mitigation Status • On track • 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 stakeholders (May 03 and beyond) Section 13 Mechanical Subsystem 117

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 118

GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD 3 Review May 12 -16, 2003 Cost and Schedule Section 13. 7 Section 13 Mechanical Subsystem 119

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 CCB Actions Affecting 4. 1. 8 Change Request # Description Status LAT-XR-01149 -01 Lockheed Martin Contract Rebaseline Approved, $56 K LAT-XR-01159 -01 Procurements Move Approved, $0 K from FY 04 to FY 03 LAT-XR-01585 -01 Transfer to 4. 1. 1. 5 Instrument Design Engineering Approved, -$1. 4 M LAT-XR-1621 -01 Mass Allocation Increase Approved, 22 kg Document: LAT-PR-01967 Section 13 Mechanical Subsystem 120

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 4. 1. 8 Work Flow Summary GRID BOX RFI 23 MAR 04 X-LAT PLATES Document: LAT-PR-01967 X-LAT PLATES & RADIATORS Section 13 Mechanical Subsystem 121

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Key Deliverable Milestones Forecast Baseline Document: LAT-PR-01967 Product Available Date Integration Need Date Section 13 Mechanical Subsystem 122

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Critical Path Document: LAT-PR-01967 Section 13 Mechanical Subsystem 123

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Budget, Cost, Performance Document: LAT-PR-01967 Section 13 Mechanical Subsystem 124

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Cost/Schedule Status • Status as of February 28, 2003: Item In k$ Budget at Complete 11, 794 Budgeted Cost for Work Scheduled (a) 4, 603 Budgeted Cost for Work Performed (b) 3, 939 Actual Cost for Work Performed 3, 543 Cost Variance 395 10% of (b) Schedule Variance -664 -14% of (a) Document: LAT-PR-01967 Section 13 Mechanical Subsystem 125

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Resource Scheduling by FY Document: LAT-PR-01967 Section 13 Mechanical Subsystem 126

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 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 Document: LAT-PR-01967 Section 13 Mechanical Subsystem 127

GLAST LAT Project Gamma-ray Large Area Space Telescope Document: LAT-PR-01967 CDR/CD 3 Review May 12 -16, 2003 Risk and Summary Section 13. 8 Section 13 Mechanical Subsystem 128

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

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Risk Summary ID # Mech 0003 Mech 308 Risk Rank Low Risk Description Risk Mitigation • 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 • 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 Mech 0004 Mech 321 Low Document: LAT-PR-01967 • 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 Section 13 Mechanical Subsystem 130

GLAST LAT Project CDR/CD 3 Review May 12 -16, 2003 Risk Summary ID # Risk Rank Risk Description Risk Mitigation • Availability of Grid and ACD-BEA for match drilling at mutually acceptable timeframes Mech 0005 Mech 323 • Establish multiple windows of opportunity to do the operation and or additional tooling • 1) Develop schedule window work-arounds (ECD – June 03) Low • 2) Evaluate creating drill template to remove schedule dependency (ECD-June 03) • Repeatable X-LAT Thermal Joint performance Mech 0006 Mech 541 • X-LAT plates are removed to service electronics boxes Moderate • X-LAT plates could be removed after LAT or Observatory thermal testing • Repeatable Radiator Thermal Joint Performance Mech 0007 Mech 542 • Same as Mech 0001 Moderate • 1) Same as Mech 0002 • “Wet” joint is disassembled & re-assemble after LAT thermal balance test • 6 joints per radiator must be made within pot life of thermal adhesive Document: LAT-PR-01967 Section 13 Mechanical Subsystem 131