GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems1 GLAST Large Area Telescope: Mechanical Systems WBS:

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems1 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems2 Overview Section 13.1 Gamma-ray Large Area Space Telescope

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems3 Mechanical Systems Organization

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems4 Mechanical Subsystems Overview +Z X-LAT Plate EMI Shields Grid AssemblyGrid Box Base AssyGrid Box Assy Radiator Mount Brkt DSHP Mid-Plate HPPP

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems5 Major Subassemblies Grid Assembly –4x4 Grid + Radiator Mount Brackets Grid Box Base Assembly (GBBA) –Grid Assy + Top Flange & Downspout HP + HP Patch Panel –Configuration delivered to I & T for LAT integration Grid Box Assembly –GBBA + EMI Skirt + X-LAT & Mid-plates –Mechanical Systems Top Assembly test configuration –Static Load and Thermal Cycle tests Radiators –Fabricated and tested by LM X-LAT and Mid-plates –Fabricated and tested by LM

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems6 Radiator & X-LAT Placement +Z

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems7 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems8 Design Problem Areas CAL-GRID Interface Electronics-Box to X-LAT Interface

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems9 Cal Plate to Grid Interface Status The design shown at PDR for the Calorimeter to Grid interface was a bolted joint with 54 - #8 bolts & 16 - #6 bolts Two pins provide alignment – one slip fit and one slot Further analysis has shown that this design is inadequate –Inadequate margin between the required friction coefficient to prevent slipping and the achievable coefficient Alternate designs are being pursued by analysis and test –Create a pinned joint using structural epoxy around a bolt –A combination of pins and bolts –An alternate path for shear loads leaving the original arrangement of bolts for clamping in Z –Unique Cal plates around the periphery The Instrument Office and the Project Office are reviewing the shear load requirements This interface remains an open issue

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems10 CAL-Grid I/F Closure Plan Re-evaluated approach for deriving the shear load requirement –Factor of ~2 reduction predicted 5/6 New shear loads from CLA –First look 5/16 –Verified5/30 EM test of CAL Shear plate concept –First look 5/21 (load capability) –Full up test 6/7 Detail design complete 6/27 –Coordinated with CAL, I & T and ELEC (cable trays) 1 x 4 EM testing complete 7/31

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems11 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 that E-boxes were not serviceable Large bonded area to de-mate. Re-verification issues after re-integrating. At 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 X-LAT to Electronics-Box Thermal Joint Design Problem Status GRID X-LAT Plate

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems12 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 graphite “felt” 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 limited Flight heritage and must be qualified for our application –GSFC Wide Field Planetary Camera 3 has qualified an application

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems13 X-LAT Vel-Therm Design Closure Plan Design trades 5/30 –Contact pressure distribution (# bolts, preload) –Particle containment –E-box – X-LAT mechanical connection details Vel-therm EM tests –Coupon tests (load-deflection & conductance-psi) 5/30 –Full scale tests 7/15 –Life tests – thermal and/or mechanical cycling 12/12 Flight designs 8/29 –Finalize interface –Revise/release affected hardware –Assembly plans & procedures –Coordinate with I & T

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems14 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.

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems15 Major RFA’s and Overall Status 19 of 46 Mechanical/Thermal RFA’s owned by Mechanical Systems (M. Campell & S. Morrison) –0 closed –19 submitted

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems16 Major RFA’s and Overall Status Top 5 RFA Summary #12 a) Address the intermetallic layer issue at the friction joint of the bimetallic joint for VCHP’s; b) request information on manufacturing processes; c) are CCHP end caps friction welded? –Leakage through intermetallic layers is an issue in pressure vessel design. It can be aggravated by the friction-welding process since these layers can be aligned to result in leak paths. LM has instituted strict controls on material purity to preclude the formation of intermetallic layers which can lead to leakage. –Temperatures are controlled during subsequent fusion welding processes to remain below approximately 200 o F. Fusion welding is automated, allowing minimum heat input to the parts. Inert gas flow provides sufficient cooling to limit temperatures during and after the welding process. This ensures that material integrity is not compromised due to overheating. LM has had no failures in these joints in over 15 years of flight experience using our material and process controls. #29 Establish a realistic schedule for drawing release include spans for design engineering, check, stress, configuration management, etc –Schedule has been revised to include these items

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems17 Major RFA’s (Cont) Top 5 RFA Summary (Cont) #34 Verify that proposed Vel-therm X-LAT to electronics thermal joint design thermal performance does not degrade over time (aging issue), after multiple installation/de-installations, and during the course of the mechanical vibration –A qualification program will be developed for this interface to address these issues. Looking for guidance from GSFC WFC- 3 program. #42a) What is the detailed schedule for the Vel-Therm EM Test program.

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems18 Major RFA’s (Cont) Top 5 RFA Summary (Cont) #42 b) What is the back-up design if the EM program is not successful using Vel Met? New baseline is unconventional. –3 Back-ups are under consideration; #1 will be developed –“Thick” RTV bond line between E-box and X-LAT plate with a 0.0005 inch thick Teflon film between one of the interfaces to allow disassembly. –A thermal strap that is laminated with the Grafoil (high conductance graphite). –Delete existing X-LAT plate and rigidly attach the X-LAT heat pipes to the E-boxes. The heat pipes would become the flexible member. A cap would fit over the entire assembly to act as EMI enclosure. Variation on this is a X-LAT plate that ties the E-boxes together, but is not tied to the EMI skirt. This keep the boxes moving in-phase.

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems19 Mechanical Systems’ Status Summary Final Design Established With Known Closure Plans For Design Trades –X- LAT Plate To Electronics Interface - ECD: 7/15/03 Qual tests ECD: 11/15/03 –CAL-Grid Interface – ECD: 7/15/03 –EM Model Tests Complete - ECD: 9/03 –Grid Box Assy Drawings – ECD: 8/03 0/26 Drawings Released, 23/26 Drawings Draft –Radiator & X-LAT Drawings – ECD: 6/15/03 0/39 LM Drawings Released, 39/39 LM Drawings Draft Internal & External Interfaces Established –87 TBX’s with closure planned – ECD: 6/1/03 Performance Analyses Will Show Compliance Including Sufficient Design Margin –Analyses ECD: 5/30/03 –Exception: CAL-Grid interface currently has negative margins Qualification & Verification Plans –X-LAT test plan ECD: 5/30/03 –GBA Static Load test case definition ECD: 8/03 –TCS Thermal Balance test definition ECD: 8/03 Subsystem Risk Areas Identified And Mitigation Plans Established Cost & Schedule Manageable –+$364K Cost and -$544K Schedule Variance with recovery plans in work –60 Days Schedule Float to Flight Delivery Need Dates

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems20 Gamma-ray Large Area Space Telescope Key Requirements Section 13.2

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems21 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 13W 22W Y D TD-00125-1(Derived) When off, orbit-average survival heater power 158W 62W Y D IRD 3.2.4.1.7.6 <220 W @ 27 V min When off, peak survival heater power < 560 W 533 27W Y D 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”

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems22 Key Mechanical Systems Requirements (2 of 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 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 LAT-TD-00225-5 (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 10.1. Structural Loads 11.1. Process and Interface Heat Loads 11 Thermal Environment and Heat Loads 615W LAT+ 35W Rad 73.4W/Rad 0W/Rad 0.6 C hot case during any normal LAT mode to IR, Albedo, Solar fluxes (Derived) * Will comply for CAL-Grid interface

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems23 Gamma-ray Large Area Space Telescope Design Design Grid Box Assembly Section 13.3

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems24 Drawing Tree

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems25 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems26 Grid Structure +Z Helicoils for CAL bolts Top Flange Heat Pipes Purge grooves S/C mount Integral Wing

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems27 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 10.25” 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 N 2 purging of the CAL’s during ground operations

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems28 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 Construction Integral part of Grid (was separate part) S/C Interface is a raised pad with 2 – 12.7 mm dia inserts & 1 – 14.3 mm dia pin hole at each location –Installed with Spectrum Astro provided fixture +Z

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems29 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 optics 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/pinned to 3 orthogonal surfaces of Grid corner

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems30 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 Construction 6061-T6 AL machining, alodine Pieces bolted to Grid & each other +Z

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems31 Calorimeter to Grid Interface Interleaved CAL baseplate tabs are bolted and pinned to –Z surface of Grid CAL baseplates close-out the Grid structure which increases natural frequency of LAT Bolted interface applies clamping force for Z axis loads and provides good thermal contact Features to carry shear loads are under investigation 2 pins per CAL locate it on the Grid bay and are used as datum for hole pattern in Grid and other features such as Tracker cable cut-outs in Grid walls

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems32 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 Graphite felt material selected –Highly conductive graphite fibers –Mechanically compliant –Meets out-gassing requirement –Vel-Therm & Vel-met are brand names

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems33 Electronics Stack Cross-Section Note: View along Y-axis Midplate to X-LAT Thermal Joint, 2 PLCS, 60 #6 Fasteners each side EMI Shields EMI Shields GRID Bolting X-LAT Plate to EMI Shields, 60 #8 Fasteners per Plate X-LAT PlateMidplateX-LAT Plate Vel-Therm 4 cm wide graphite felt strip placed around perimeter of each box optimizes conduction vs contact pressure required

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems34 Stress Analysis Topics Cal-Grid interface load recovery Grid Stress analysis Radiator Mount Bracket analysis

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems35 CAL Interface Load Recovery CAL-Grid joint –1152 connections (72 per CAL module) –CAL plate stiffens 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 (X & Y) loads at the pin locations and Z loads at bolt locations –EM pinned joint tests validated manufacturability but insufficient load capacity Demonstrated Load Capacity Best We Can Do* Capacity req’d at highest loaded tab with 1.25 factor Grid Wall 750 lb 925 lb 1460-2010 lb Cal Plate Tab 750 1300 1460-2010 * Includes 0.160 close fit pin in grid wall and CAL plate tab and material properties of 2618A for CAL plate

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems36 Grid Stress Analysis Grid stress analysis indicates positive margins of safety for all regions –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 Highest stresses occur in transition regions around SC mount 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems37 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 Study results –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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems38 Summary 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems39 Gamma-ray Large Area Space Telescope Verification Program Grid Box Assembly Section 13.4

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems40 Grid Box Assembly Verification Topics EM Tests Qualification & Flight Test Overview Mechanical Systems Verification Test Flow Mechanical Systems Verification Matrix

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems41 EM Test Plans Overview EM test plans developed for: –CAL-Grid Joint Testing (complete) Friction characterization Bolt-Helicoil pair characterization Bolted Pull tab coupons Pinned Pull tab coupons –1x4 Grid –Grid heat pipe bonding process qualification –Thermal Joint candidates (complete) “Wet” adhesive or gasket Low contact pressure No contact pressure –X-LAT heat pipe characterization (complete)

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems42 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems43 Planned Process Tests 1 x 4 Grid unit fabrication Objectives –Demonstrate Grid manufacturability –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)

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems44 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 Results –Conductance values agree with published data –Nusil CV2946 is difficult to work with –Single 3 way joint assembled Risks mitigated –Validates thermal model based on empirical thermal conduction values

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems45 Thermal Joint Further Work Demonstrate Radiator installation process –6 wet RTV joints in vertical orientation & restricted access –Complete within pot life limits (bonded & torqued) –Verify bond line integrity (uniform thickness & % voids) Demonstrate Radiator removal process –Separate 6 joints with restricted access –No damage or distortions of heat pipes –Verify material can be cleaned up & surface prepared again for another bond

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems46 X-LAT to E-box Thermal 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 or Vel-Met) No contact pressure joints –High conductivity materials mechanically fastened at both ends –Formed Copper sheets (30 mils) –Pyrolytic Graphite Sheet (4 mils thick stock) Conductance vs. various gaps and/or pressures examined

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems47 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 –.125” thick material can fill gap of.05 to.10” Quantify contact pressure versus brush compression

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems48 Planned Work Additional Vel-Therm coupon tests –Conductance in high vacuum vs. contact pressure Additional thermal joint configuration tests –Mock up box stackup configuration with heaters on sidewalls to simulate electronics heat source –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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems49 X-LAT EM Heat Pipe Characterization Tests Objectives –Verify thermal performance of EM X-LAT heat pipe in simulated on-orbit thermal cases Key Result –Alternate Heat Pipe condensers at each end were cycled on and off without Heat Pipe dry out. –Heat pipe was not sensitive to small tilt angles at the thermal loads applied Risks mitigated –Demonstrate adequate design margins –Assure that heat pipe performs as predicted

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems50 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems51 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems52 4 x 4 Grid Structure Verification Mass Properties & C.G. Verified Dimension Check Verified Proof Test of Inserts

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems53 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems54 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems55 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems56 Gamma-ray Large Area Space Telescope Fabrication Process Grid Box Assembly Section 13.5

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems57 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)

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems58 Grid Box Machining Assembly “Grid Box Machining” is a temporary assembly for machining: –EMI shields coplanar for X-LAT plate mounting –Each pair of Radiator Mounting Brackets coplanar –Control relative positions of Radiator & X-LAT locating pins to Grid datum’s so 3 sets of heat pipes will mate properly Install the EMI Skirt components on Grid Machine bottom edges of the EMI Skirt components co-planer Machine X-LAT locating pin holes and fastener holes in the EMI Skirt components Machine mounting features & locating pins holes in Radiator Mounting Brackets Install locating pins and Helicoils Mark parts for specific location on Grid Radiator Pins X-LAT Pins

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems59 Design, Analysis & 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems60 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems61 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems62 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 DSHP’s 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 TFHP’s to the radiator heat pipes

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems63 Heat Pipe Sizing All worst case pipe requirements derived from detailed thermal model hot case with the following assumptions and results

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems64 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 analysis 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems65 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems66 Outer Facesheet VCHPs Honeycomb Core Inner Facesheet Doublers Reservoir Support Bar 1.56 m 1.82 m Radiator Panel, Exploded Z X Y

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems67 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems68 Radiator Stress Analysis Detailed Results Face Sheet Margins Facesheet stress analysis indicates positive margins of safety for all high- stress regions Facesheet material properties –Material: 6061-T6 aluminum (Top: 0.060” thk, Btm: 0.030” thk) –Ftu = 296 MPa (43 ksi) –Fty = 255 MPa (37 ksi) MSy = Fty/( 1.25  i ) –1 MSu = Ftu/( 1.4  i ) –1 Facesheet Stresses and Margins of Safety

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems69 Radiator Stress Analysis Detailed Results Core Shear Margins Core shear stress analysis indicates positive margins of safety for all high- stress regions –Basic Core Material: 5000 series aluminum Fsu12 = 35 kPa (5 psi) Fsu13 = 1379 kPa (200 psi) Ribbon Dir; Fsu23 = 758 kPa (110 psi) –Hi_Den Core Material: 5000 series aluminum, density is ~2*basic core density Fsu12 = 69 kPa (10 psi) Fsu13 = 3.62 MPa (525 psi) Ribbon Dir; Fsu23 = 2.10 MPa (305 psi) Bi-axial quadratic failure criterion: MSu = 1/SQRT((Fs.  yz /(Ks*Fsu13)) 2 + (Fs.  xz /(Ks*Fsu23)) 2 ) -1 Where: Ks=0.9 Core Stresses and Margins of Safety LD = Basic core material HD = High density core material

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems70 Radiator Stress Analysis Detailed Results Heat Pipe Margins Heat pipe stress analysis indicates positive margins of safety for all stressed regions Heat pipe material properties –Material: 6063-T6 aluminum –Ftu = 241 MPa (35 ksi); Fty = 214 MPa (31 ksi) MSy = Fty/( 1.25  i ) –1 MSu = Ftu/( 1.4  i ) –1 Heat Pipe Stresses and Margins of Safety (includes 170 psi int. pressure)

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems71 Radiator Stress Analysis Detailed Results Bolt/Insert Margins Bolt and insert analysis indicates positive margins of safety Bolt material properties –Material: CRSS A-286 stainless steel –Ftu = 1.103 GPa (160 ksi); Fty = 0.827 GPa (120 ksi) –Fsu = 0.655 GPa (95 ksi) Insert ultimate strengths (Estimated from existing tests. GLAST specific tests to be performed) –5/16”-24 UNF insert Pull-out = 6.47 kN (1454 lb) Shear = 7.16 kN (1610 lb) –10-32 UNF insert Pull-out = 3.56 kN (800 lb) Shear = 4.79 kN (1077 lb) MSy = Fty/( 1.25  i ) –1 MSu = Ftu/( 1.4  i ) –1 Bolt and Insert Stresses and Margins of Safety * Note: Factor of safety on Ultimate = 1.4, Yield = 1.25, Fittng factor = 1.15

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems72 Radiator Thermal Performance Summary LAT input powers –Q max = 602 W (615 W analyzed) –Q min = 475 W (495 W analyzed) 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 = 0 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 < 58 W * –Predictions T min RIT = -20 °C Q avg Reservoir = 42 W Cold RIT Temperatures * Value pending

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems73 Radiator Requirement Compliance (1 of 2) Key requirements not formally defined or compliance is in question * Specification Change Pending

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems74 Key requirements not formally defined or compliance is in question Radiator Requirement Compliance (2 of 2) * Specification Change Pending

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems75 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 –Expected mitigation is to change requirement of dynamic envelope to +2 mm beyond static envelope. –If change is not incorporated, can reduce thickness of honeycomb core Impact to structural design margin

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems76 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 (1 pinch per fill tube) –Increase cost risk Power allocations –Expected mitigation is to impose requirements that bound current design case (see compliance tables). –If power can not be allocated, can do all or some of the following Decrease radiator size –Impact to hot case LAT temperatures

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems77 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems78 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems79 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems80 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)

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems81 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems82 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems83 X-LAT Requirement Compliance The following table addresses key requirements that are not yet defined

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems84 X-LAT Compliance Mitigation Plans Must define/finalize requirements and determine whether 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems85 Verification Radiator and X-LAT Assemblies Section 13.7 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems86 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems87 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems88 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 into page Cold Wall Flight Radiators (2) MLI Blanket NO SCALE X-LAT Assy

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems89 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems90 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems91 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems92 Gamma-ray Large Area Space Telescope Cost and Schedule Section 13.8

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems93 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-01621-01Mass Allocation Increase Approved, 22 kg LAT-XR-01752-02SLAC/HEPL Labor Escalation Rates Approved -$39K

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems94 4.1.8 Work Flow Summary

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems95 Key Deliverable Milestones Product Available Date Integration Need Date Forecast Baseline Forecast Baseline

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems96 Critical Path

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems97 Budget, Cost, Performance

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems98 Cost/Schedule Status Item In k$ Budget at Complete 10,373 Budgeted Cost for Work Scheduled (a) 4,643 (a) Budgeted Cost for Work Performed (b) 4,099 (b) Actual Cost for Work Performed 3,735 Cost Variance 364 8.9% of (b) Schedule Variance -544-11.7% of (a) Status as of March 31, 2003:

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems99 Procurements Long-Lead Procurements –Aluminum Billets (placed) –Heat pipe extrusions (LM - placed) –Solid State thermostats (LM) Major Upcoming Procurements Near-Term (< 4 months) –Lockheed Martin Phase 2 –Grid Assembly –Flight Hardware for Thermal Control System Major Upcoming Procurements Long-Term (>4 months) Minor Upcoming Procurements –GSE –Grid Assembly Fixtures, Test Equipment –Thermal-vac Test Fixtures

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems100 Gamma-ray Large Area Space Telescope Risk and Summary Section 13.9

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems101 Risk Summary ID #Risk RankRisk DescriptionRisk Mitigation Mech 0008 High Ability to ramp up & maintain personnel required to execute Mechanical Systems plan Update manpower plan. Locate or request additional funds. Hire additional help. Negotiate transition of technicians from MECH to I&T that is acceptable to both with IPO buy in.

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems102 Risk Summary ID #Risk Rank Risk DescriptionRisk Mitigation Mech 0001 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 0006 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems103 Risk Summary ID #Risk RankRisk DescriptionRisk Mitigation Mech 0009 Moderate Delays in Lockheed Martin document finalization may impact cost & schedule. Release Radiator & X-LAT level IV specifications & IDD's by 5/12/03 All future changes controlled by formal revision through Contracts Mech 0010 Moderate Incorrect hardware may be built due to changes and proposed changes being given to various LM personnel Release controlling documents. Changes to these documents to be sent through Contracts (May 03 and beyond)

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems104 Risk Summary ID #Risk Rank Risk DescriptionRisk Mitigation Mech 0007 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 Mech 0002 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)

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems105 Risk Summary ID #Risk RankRisk DescriptionRisk Mitigation Mech 0005 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)

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems106 Gamma-ray Large Area Space Telescope Appendix A Requirements

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems107 Topics Agenda 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems108 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-00124-3 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems109 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems110 Driving Design Requirements (Radiator: Mechanical)

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems111 Driving Design Requirements (Radiator: Structural)

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems112 Driving Design Requirements (Radiator: Thermal)

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems113 Driving Design Requirements (Radiator: Mechanical)

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems114 Driving Design Requirements (X-LAT)

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems115 Gamma-ray Large Area Space Telescope Appendix B Fabrication Process Grid Box Assembly

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems116 Topics Agenda Fabrication plans Assembly plans MGSE Performance and Safety Assurance plans Further Work

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems117 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)

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems118 LM M & P Plan & EEE Parts LM M & P Plan submitted to SLAC (GLS00018-2, dated 1 Feb 2003) LM 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems119 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)

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems120 Grid Assembly The Grid Assembly consists of; 4 x 4 Grid Radiator Mounting Brackets - 2 as shown and 2 opposite. Radiator Mounting Bracket Grid Assembly

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems121 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems122 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems123 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems124 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems125 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems126 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

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems127 Mechanical Systems MGSE

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems128 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.

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems129 Gamma-ray Large Area Space Telescope Appendix C Peer Review RFAs

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems130 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 1Open Verify that Grid Finite Element Model reflects the flange cutaways for the downspout heat pipes. Assess stress concentrations at these reduced flange section areas. The Grid has been re-designed to incorporate the spacecraft interface wing as an integral feature of the grid. The lower flange has been extended to become the wing. This removes the discontinuities that were in the old design. Analysis for this new design has just begun. ECD: 5/12/03 10Open Complete design and structural analysis of S/C to LAT interface. Present margins of safety for LAT side of interface hardware Analysis is in work. ECD: 5/12/03

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems131 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 12Open 1) Address the intermetallic layer issue at the friction joint of the bimetallic joint for VCHPs. 2) What does LMC do from a manufacturing process point of view to preclude this layer from forming during the integration welding process, including temperature control during processing? 3) Do LMC CCHPs use a friction weld to cap off CCHPs? Leakage through intermetallic layers is an issue in pressure vessel design. It can be aggravated by the friction-welding process since these layers can be aligned to result in leak paths. LM has instituted strict controls on material purity to preclude the formation of intermetallic layers which can lead to leakage. Temperature control is not directly applicable to the friction welding process, however other process controls on weld energy are used in conjunction with weld process certification to carefully regulate weld quality. LM has had no failures in these joints in over 15 years of flight experience using our material and process controls.

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems132 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 27Open Please identify and capture development of process specifications for adhesive applications, painting (if any) etc LAT processes are being developed by Jerry Clinton. MECH specific processes will be developed and written prior to flight hardware assembly. Here is a list of processes MECH will use in the assembly of the Grid Box Assembly.

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems133 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 28Open Review heat pipe installation to see whether any protection covers can be used during ground handling and mechanical operations to prevent any accidental damage. Both the grid and radiator design appears to be vulnerable to damage. Protective covers will be used for as long as practical. They have been added to the MECH MGSE list. 29Open Establish a realistic schedule for drawing release with “buyin” from all parties required for process completion, i.e. design engineering, check, stress, configuration management, etc The drawing release plan is being revised to add time for feedback from the interested parties. ECD: 5/12/03 32Open Verify ESD requirements are correctly flowed down to LMC from LAT Working with ELEC to define applicable ESD requirements to flow down to LM. ECD: 5/12/03

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems134 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 33Open The plan is to put the anti- freeze heaters on the front/FOSR side of the radiator and have the FOSR cover the heater. Look at the impact of putting the heater on the backside. At the temperatures the anti-freeze heaters will operate, the panel gradients should be small (small qdot = small delta T). A study will be performed to evaluate the anti-freeze heater design. Specifically, the study will address the plausibility of placing the anti-freeze heaters on the non- radiating side of the radiators. It is anticipated that this study will be complete by CDR. 5/12/03

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems135 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 34Open Verify that proposed Vel-therm X-LAT to electronics thermal joint design thermal performance does not degrade over time (aging issue), after multiple installation/de- installations, and during the course of the mechanical vibration these program. A qualification program will be developed for this interface to address these issues. However, the Wide Field Planetary Camera-3 (WFC3) is a GSFC program that used this material. The instrument is waiting to fly. Therefore, it must have qualified and acceptance tested. If GSFC could provide the details of what testing was done and the test results, it would streamline our testing. Perhaps there is Qual by Similarity possibilities here that would reduce costs as well.

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems136 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 36Open Define allowable load transfer into LAT (or radiator strut stiffness) at connection of radiator to S/C. An effective stiffness of the spacecraft support strut of at least 200,000 lb/in (strut plus Spacecraft) was used in the Radiator analysis. This should be flowed down to Spectrum Astro in the S/C working group or as a requirement from GSFC to Spectrum. 37Open Limit load tests should qualify the design (1.25 x flight limit loads) The Level IV spec will be revised. ECD: 5/12/03 38Open Update yield F.S. to 1.25 (currently @1.1). Verify that this requirement has been flowed down to all other subcontractors. The Level IV spec will be revised. ECD: 5/12/03 39Open Provide more detailed summary of stress margins of safety for the LAT instrument. Stress analyses are in work. ECD: 5/12/03

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems137 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 40Open Review high conductance graphic interface material available from a company named “UCAR” (formerly part of Union Carbide). They have high conductance graphite material gaskets greater than 10 mil in thickness. They have space experience. Received 0.020” & 0.025” thick samples from Vendor. While the material (Grafoil) has excellent compressive properties, it has very low tensile strength (~1,000 psi). Therefore, when bending the material, it breaks. We are investigating laminated versions of the product to see if they are feasible for this application. 41Open Verify that the flight data certification packages that accompany hardware delivered by Lockheed to SLAC are consistent with NASA Quality Assurance Requirements. NASA has not imposed any requirements for data package requirements on LAT (per Darren Marsh). However, Lockheed’s data package will be consistent with the LAT’s internal requirements (Mechanical to I & T) and their own standards for their Government Customers.

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems138 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 42Open 1) What is the detailed schedule for completion of the EM Test program for the X-LAT Thermal/Mech Design, will it be complete by CDR? 2) What is the back-up design if the EM program is not successful using Vel Met? New baseline is unconventional 1)EM test program schedule (below)

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems139 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 42 Cont. Open 1) What is the detailed schedule for completion of the EM Test program for the X-LAT Thermal/Mech Design, will it be complete by CDR? 2) What is the back-up design if the EM program is not successful using Vel Met? New baseline is unconventional 2) Back-up designs (in descending order) “Thick” RTV bond line between E-box and X-LAT plate with a 0.0005 inch thick Teflon film between one of the interfaces to allow disassembly. The existing push-pull bolts would still be required for Z axis restraint (parts are not bonded together). A thermal strap that is laminated with the Grafoil (high conductance graphite, see RFA # 40). Delete existing X-LAT plate and rigidly attach the X-LAT heat pipes to the E- boxes. The heat pipes would become the flexible member. A cap would fit over the entire assembly to act as EMI enclosure. Variation on this is a X-LAT plate that ties the E-boxes together, but is not tied to the EMI skirt. This keep the boxes moving in phase.

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems140 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 43Open Consider including GRID & DSHPs in the “Complete TCS” TB test. Schedule chart 1.2-4 shows cycling of grid assy by ¾ with “complete TCS test” in 6/04. Chart on page 3.1-10 conveys this config for the TB test Definition of the test & hardware requirements is in work. Examining schedule options including combining the thermal vacuum acceptance testing of the radiators & X-LAT plates with this TCS TB test. The Grid delivery to I&T need date currently precludes its availability for this test, but will be part of configuration trade study (configuration vs. cost, schedule & risks mitigated). ECD: 7/13/03

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems141 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 45Open GSFC (Brad Parker/Materials Board) provide recommendation to SLAC/LM team regarding the use of bimetal element used in heatpipes Same as #12. Leakage through intermetallic layers is an issue in pressure vessel design. It can be aggravated by the friction-welding process since these layers can be aligned to result in leak paths. LM has instituted strict controls on material purity to preclude the formation of intermetallic layers which can lead to leakage. Temperature control is not directly applicable to the friction welding process, however other process controls on weld energy are used in conjunction with weld process certification to carefully regulate weld quality. LM has had no failures in these joints in over 15 years of flight experience using our material and process controls.

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems142 RFA Response ID #StatusRFA DescriptionRFA Response/Closure Plan 46Open Consider defining a “control performance” test for each VCHP that verifies ability to entirely block off the condensor, as well as ability to run full open under spec boundary conditions Will add a “Qualification” (one time-one part) test to the Lockheed Martin Radiator specification and/or SOW. ECD 5/12/03

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems143 Gamma-ray Large Area Space Telescope Risk & Summary Back-up charts Section 13

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems144 CAL-Grid I/F Closure Plan New shear loads from CLA –First look 5/16 –Verified5/30 EM test of CAL Shear plate concept –First look 5/21 (load capability) –Full up test 6/7 Detail design complete 6/27 –Coordinated with CAL, I & T and ELEC (cable trays) 1 x 4 EM testing complete 7/31

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems145 Cal Plate to Grid Interface Status Loads analysis of interface used to determine required friction coefficients to prevent slipping at cal tab locations. Required friction compared to that determined to be achievable in test. –The upper limit of friction achievable with special surface treatments is needed to prevent slipping with the baseline design. –Devices to increase clamping force at perimeter of grid still require friction coefficients at a small number of locations which exceed the friction achievable with normal surface finishes. –Friction alone has not been shown to provide high confidence that local (not bulk) slipping will not occur. Analysis to determine load redistribution and potential for subsequent slipping after initial slipping is not readily accomplished.

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems146 Cal Plate to Grid Interface Status (cont) Converting select fasteners in clearance holes to pins via epoxy fill of the clearance gap studied as a means to provide confidence against local slipping. –Epoxy installation technique and strength demonstrated on test coupons. –Upon application of shear load, male threads of fastener mating with female threads in grid rib cause excessive dead band. Mated threads do not effectively carry shear loads. Other techniques for strengthening the interface under study –Replace select fasteners with traditional shear pins in tight holes. Requires template for drilling grid and cal plates. Most dead band found in threads will be eliminated but strength of grid walls and / or cal tabs may be inadequate. –Carry shear loads directly from cal plates to grid wings by adding shear plates that attach to cal plates at existing GSE fastener location. Existing fasteners from cal plates to grid provide axial restraint forces.

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems147 5/16 bolts pressed or tight slip fit into CAL plates and Grid perimeter. Cal plate location is at current location of tapped GSE hole. Grid perimeter CAL Shear Plate Concept

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems148 CAL Shear Plate Concept PRO’s Allows shear loads to be carried to be carried through M8 ( 5/16 inch) fasteners Cal plate tabs and grid walls are not in the primary shear load path No dependence on friction Minor changes to cal plates and wings. Epoxy shear holes will be in shear plates so that no holes need to be drilled in M8 fasteners. CON’s Mold release and a design feature are required on bolts with epoxy fill in order to accomplish shear plate removal. Some additional confidence testing in epoxy is required. Clearance envelope above the pressed in bolts in the cal plate needs to be checked. Removal of a cal plate requires removal of shear plates on adjacent cal plates

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems149 X-LAT Vel-Therm Design Closure Plan Design trades 5/30 –Contact pressure distribution (# bolts, preload) –Particle containment –E-box – X-LAT mechanical connection details Vel-therm EM tests –Coupon tests 5/30 –Full scale tests 7/18 –Life tests – thermal and/or mechanical cycling 12/12 Flight designs 8/29 –Finalize interface –Revise/release affected hardware –Assembly plans & procedures –Coordinate with I & T

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems150 X-LAT Back-up Thermal Design Plans Develop concepts 1.“Thick” RTV bond line between E-box and X-LAT plate with a 0.0005 inch thick Teflon film between one of the interfaces to allow disassembly. The existing push-pull bolts would still be required for Z axis restraint (parts are not bonded together). Complete 2.A thermal strap that is laminated with the Grafoil (high conductance graphite, see RFA # 40). ECD 5/30 3.Delete existing X-LAT plate and rigidly attach the X-LAT heat pipes to the E-boxes. The heat pipes would become the flexible member. A cap would fit over the entire assembly to act as EMI enclosure. Variation on this is a X-LAT plate that ties the E-boxes together, but is not tied to the EMI skirt. This keep the boxes moving in phase. ECD ? Need Analysis Coupon test #1 6/13

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems151 X-LAT Plate Thermal Loads -X Note: View from X-LAT Plate to E-boxes Power shown include 15 W from TEM/TPS boxes Heat Source within box X-LAT Heatpipe 6 Required Power numbers Source: LAT-TD-00225-4 (draft) 15W +Y 21W 37W 15W 42W EPU 39W SIU EPU 39W PDU EPU 39W GASU

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems152 Particulate Containment Options Perimeter (foam) gasket Tape over the Vel-therm Vel-therm sandwich between 2 Aluminum plates with Kapton tape close outs Shower cap bonded to X-LAT & slip over E-box

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems153 Conductance vs Pressure

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems154 Vel-Therm Pressure vs. Deflection Vel-Therm Pressure vs. Deflection

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems155 Drawing Release Plan

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems156 Summary of Margins of Safety 22 24 23 11 13 12 25 14 26 Tension Failure Bearing Failure Tear Out Failure 15 16 27

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems157 Topics Agenda Mechanical design changes since ∆PDR Impacts on Subsystem design Studies since Delta PDR

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems158 Design Changes Since Delta PDR X-LAT to E-Box thermal joint –WAS: Rigid bonded joint with flexures at CAL-TEM interface –IS: Rigid interface at CAL-TEM with compliant joint at X- LAT plate and a thermal velvet material (Vel-therm) used to fill gap between bottom box & X-LAT X-LAT plate WAS: honeycomb panel; IS:.125” plate CAL-Grid bolts: Use #8’s everywhere except at TRK cables pass-thru’s to increase clamping force on CAL plate

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems159 Design Changes Since Delta PDR Refined S/C interface stiffener (wing) to reduce grid distortions S/C attach method –WAS: onto –Z surface of Grid –IS: tang that protrudes down from wing S/C stayclear & center EMI shield design modified to accommodate above

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems160 Design Changes Since Delta PDR E-box harnesses –WAS: bulkhead connectors in EMI skirt –IS: 8 Connector patch panels into EMI skirts that E-box harness mount directly to Added 2 TCS external box & 2 brackets – mounting accommodated on Radiator Mount Brackets Added vents to EMI Electronics enclosure

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems161 Design Changes Since Delta PDR Radiator Heat Pipes –WAS: U shaped bend to Grid –IS: S shaped bend to Grid Radiator panel has top stepped for integration access Radiator – SC interfaces have been finalized –SA Boom cutout size & location, strut locations Radiator reservoir size –WAS 300 cc; IS: 75 cc Radiator VCHP extrusion –WAS 1.75” wide; IS: 2.0” wide LM will design, fabricate and test X-LAT plates

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems162 Impact of Changes on Subsystem Designs LAT –No impact TKR –No impact CAL –Baseplate design has been modified for #8 fasteners ACD –No impact Electronics –Improved reliability by reducing bulkhead connection –External TCS boxes have been accommodated Conclusion: Changes consistent with PDR to CDR design maturity. Design changes have been incorporated within the Mechanical Subsystem

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems163 Studies since Delta PDR X-LAT to Electronics Thermal Joint Design Optimize joint design to accommodate –Maximum thermal conductance –Repeatable and verifiable thermal joint –Ease of integration & removal to service E-boxes –Compliance in X-Y plane required either at E-box to CAL or E-box to X-LAT –Tolerance stack up of E-boxes, EMI skirts & CAL plates RTV, thermal gaskets, spring fingers, thermal straps and Vel- Therm traded Compliant joint at E-box to X-LAT interface with Vel-Therm material in between selected.

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems164 Studies since Delta PDR CAL-Grid interface shear load capability –No bulk movement of CAL with 70 Fasteners & μ=.01 –Isolated concern as small local motions of Grid wall underneath grid tabs –Optimize wing design to reduce loads (FEM) –Examined friction of various surface treatments –Examined Tungsten Carbide flame spray as a way to guarantee high coefficient of friction at interface –Maximized clamping force available from fasteners –Examined backing bars on top of CAL tabs to create “double shear” joint –Examined perimeter clamping bars that increase preload on all CAL tabs around the perimeter of the Grid –Developed maps from FEM showing required coefficient of friction at each bolt location for a given clamping force

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems165 Studies since Delta PDR CAL-Grid interface shear load capability (cont) Summary: A friction joint will prevent bulk slippage of the CAL and maintain the LAT natural frequency. 89% of fasteners require μ < 0.2. Plan to run an analysis to show that load redistribution for the remaining 11% does not adversely affect the LAT natural frequency. GSFC has recommended that a bolted-pinned joint be adopted. –Design implementation study and impact study would be the next step.

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems1 GLAST Large Area Telescope: Mechanical Systems WBS:

Similar presentations

Presentation on theme: "GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems1 GLAST Large Area Telescope: Mechanical Systems WBS:"— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems1 GLAST Large Area Telescope: Mechanical Systems WBS:

Similar presentations

Presentation on theme: "GLAST LAT ProjectCDR/CD-3 Review May 12-16, 2003 Document: LAT-PR-01967Section 13 Mechanical Systems1 GLAST Large Area Telescope: Mechanical Systems WBS:"— Presentation transcript:

Similar presentations

About project

Feedback