GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 1 GLAST Large Area Telescope: Mechanical Systems Peer Review March 27, 2003 Section 5.1 – Grid Box Design Marc Campell SLAC Mechanical Systems Mgr. Gamma-ray Large Area Space Telescope

GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 2 Topics Agenda Key Requirements Design Details Further Work

GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 3 Key Mechanical Systems Requirements WC= Will Comply

GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 4 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 ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 5 X-LAT Plate to E-Box Thermal Joint Thermal joint must –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

GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 6 Electronics Stack Cross-Section Note: View along Y-axis Midplate to X-LAT Thermal Joint, 2 PLCS, Approx. 60 #6 Fasteners each side EMI Shields EMI Shields GRID Bolting X-LAT Plate to EMI Shields, Approx. 60 #8 Fasteners per Plate X-LAT PlateMidplateX-LAT Plate Vel-Therm 4 cm wide Vel-Therm strip placed around perimeter of each box optimizes conduction vs contact pressure required

GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 7 EMI Shield 6061-T6 AL machining, alodine Pieces bolted to Grid & each other Encloses LAT Electronics boxes (EMI tight) Consists of 4 Radiator Mount Brackets, 4 Heat Pipe Patch Panels, 4 X-side Shields and 4 center Shields Mechanically supports 3 way heat pipe joint – Downspout, X- LAT and Radiator HP’s Supports X-LAT plates Provides mounting for Connecter Patch Plates from Electronics Provides for venting of enclosure +Z

GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 8 Radiator Mount Bracket 6061-T6 Al machining, alodine Bolts to 3 orthogonal surfaces of Grid corner 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)

GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 9 Spacecraft Interface Stiffener (Wing) 6061-T6 machining, alodine Bolted, pinned & keyed to Grid 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) +Z

GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 10 Calorimeter to Grid Interface This interface is part of the Grid stiffness design. Interleaved CAL baseplate tabs are bolted to –Z surface of Grid CAL baseplates close-out the Grid structure which increases natural frequency of LAT Bolted interface applies clamping force over large area (~4223 mm 2 per CAL) to develop shear load capability 2 pins per Grid bay locate CAL and are used to locate hole pattern in Grid and other features such as Tracker cable cut- outs in Grid walls 54 - # #6 + 2 – 0.156” dia alignment pins per CAL

GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 11 Calorimeter to Grid Interface (cont) Perimeter backing bars engage the outer tabs of the outer CAL’s to double the clamping force on these highly loaded tabs Additional clamping force can be obtained using 200 ksi bolt material Looking down +Z

GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 12 Grid Machined from 10” thick 6061 AL plate Heat treated to T6 after rough machining 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 move heat out –Downspout Heat pipes tie Grid to Radiators Thermostatically controlled heaters on Grid corners are part of LAT thermal control system Grid surface is alodine, class 3. Electrically conductive and good surface for adhesive bonding thermal components, harness supports, Tracker cables, MLI supports, EMI tape etc Integral purge grooves allow for N2 purging of the CAL’s during ground operations

GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 13 Grid Structure +Z Helicoils for CAL bolts Top Flange Heat Pipes Purge grooves

GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 14 Grid Hole Count

GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 15 Work to Close Out 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

GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Document: LAT-PR-0XXXX Section 5.1 Grid Box Design 16 End of Section 5.1 Section 5.1