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Mechanical Systems

Gamma-ray Large Area Space Telescope. Mechanical Systems. GLAST Large Area Telescope: Marc Campell SLAC Subsystem Manager marcc@slac.stanford.edu (650) 926-4658. Overview – MECH SYS Responsibilities. Grid Box Base Assembly (GBBA)

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Mechanical Systems

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  1. Gamma-ray Large Area Space Telescope Mechanical Systems GLAST Large Area Telescope: Marc Campell SLAC Subsystem Manager marcc@slac.stanford.edu (650) 926-4658

  2. Overview – MECH SYS Responsibilities • Grid Box Base Assembly (GBBA) • Grid + Radiator Mount Brackets + Top Flange Heat Pipes + Thermal Control hardware • Configuration delivered to I & T for LAT integration • Grid Box Assembly (Qual unit only) • Grid #2 is Qualification unit • GBBA + EMI Skirt + Dummy CAL Baseplates • Combined Grid Static Load and LAT strength test • Radiators • Fabricated and tested by LM • X-LAT Plates • Fabricated and tested by LM

  3. 1.6 m 1.6 m .24 m Mechanical Subsystems Overview 4 x 4 Grid >> Grid Box Base Assy >> Grid Box Assy Test Configuration (CAL Baseplates not shown) Shear Plates TFHP EMI Shields Radiator Mount Brkt TCS Hardware

  4. Radiator Panel - Exploded View Variable Conductance Heat Pipe FOSR Honeycomb Core Outer Facesheet Doublers 1.56 m Z Y X Inner Facesheet Reservoir 1.82 m Reservoir Support Bar

  5. +Z +Z Radiator & X-LAT Placement Top Flange Heat Pipe 3 Way Heat Pipe Joint Down Spout Heat Pipe X-LAT Heat Pipe

  6. Recent Accomplishments Grid Box • Grid #1 rough machining complete • Grid #1 finish machining 50% complete (shown below) • Grid #2 rough machining & heat treat complete

  7. Recent Accomplishments (cont) Lockheed Martin • Downspout Heat Pipes complete (shown below) • Top Flange Heat pipes complete • Radiator detail parts fabrication 20% complete

  8. Mechanical Systems Critical Path Flight Hardware for TCS 6/30/04 / 0 Grid Box Base Assembly #1 Operations 7/22/04 / 0 Flight Grid RFI #1 7/22/04 / 0 GBA Assembly fixtures/ MGSE 6/30/04 / 0 Fabricate Flight Grid (4X4) #1 6/15/04 / 0 Inspect Flight Grid, EMI skirt, details #1 06/16/04 / 0 GBA #1 Fit Check Operations 6/30/04 / 0 Fabricate EMI skirt, Grid details) #1 6/15/04 / 0 Inspect Flight Grid, EMI skirt, details #2 9/3/04 / 0 Fabricate Flight Grid (4X4) #2 8/27/04 / 0 Grid Box Assembly #2 Operations 10/18/04 / 0 Static Load Test Complete 12/16/04 / 0 Completion Dates/Variance to Baseline

  9. Rationale for Second Grid • LAT Sine Burst (Strength) Test deleted Fall 2003 • Concerns about over-testing LAT • Objectives could be met by adding test cases to Grid Static Load Test • Results approximately 1 year earlier • Reduced LAT schedule • Grid Static Load plan changed during Re-baseline • Original plan was to rough machine second grid and hold as flight spare • Re-baseline plan completes machining of second Grid and components required to complete Grid Box Assembly • Perform test on second grid as a Qualification test • Pulled delivery of Flight unit (Grid #1) forward approximately 2 months and maintain delivery to I & T milestone

  10. Radiator Critical Path VC Heat Pipe Fab 5/19/04 / 0 Radiator Assy Complete 11/28/04 / 0 Radiator Details Fab 5/19/04 / 0 Protoqual Testing Sine Vibration Survey 12/15/04 / 0 Acoustic Test 1/28/05 / 0 Sine Vibration Survey 2/14/05 / 0 Thermal Vacuum / Balance Test 4/7/05 / 0 Deliver to SLAC 4/21/05 / 0 Completion Dates/Variance to Baseline

  11. X-LAT Plate Critical Path X-LAT Heat Pipe Fab 9/15/04 / 0 X-LAT Plate Assy Complete 10/29/04 / 0 P/Qual Thermal Vacuum Test 11/30/04 / 0 Deliver to SLAC 12/09/04 / 0 Completion Dates/Variance to Baseline

  12. Open Issues • Radiator VCHP Helium leak rate may impact ACD Photomultiplier Tubes (PMT’s ) • LM can substitute another inert gas, but it impacts ground (not on-orbit) performance. • LM given the “OK to Fab” the VCHP’s up to the charging operation (3rd week of April). • Dispersion analysis is underway to evaluate impacts to PMT’s. ECD: 4/16/04 • Coordination of TCS validation, LM Radiator Thermal Vacuum & Balance test plans • TCS risk assessment and Qual test plan requested by GSFC. ECD: 4/30/04 • TCS – location of Grid heaters, thermostats, RTD’s and associated wiring needs to be finalized (top assembly drawing) • ECD: 5/3/04 • Radiator integration sequence • Grid has been modified to allow integration via pure translation of the Radiators. • Demonstration and detailed procedure are in work. ECD: May 04

  13. Risk List

  14. Key Schedule Issues • Problem: Late changes to Grid interface requirements • Impact: Grid #1 delivery from Tapemation (vendor) • Is: 6/15/04; Re-Baseline: 3/30/04 • Mitigation steps taken or planned to get back on schedule: • Freeze Grid design (interfaces) and build it • Reduced Grid plating time 4 weeks by changing thermal requirement from 3 to 2 plating types (Alodine and Nickel plating – black anodize deleted) • Working with Tapemation to incorporate producibility improvements to design

  15. Key Schedule Issues (cont) • Problem: Late Grid delivery to SLAC drives delivery to I&T • Impact: Grid to I & T delivery date • Is: 7/22/04; Re-Baseline: 6/15/04 • Mitigation steps taken or planned to get back on schedule: • Static Load testing on second Grid established during re-baseline activity • Minimized Mechanical Systems assembly operations • Deleted Grid Box Assembly operations (fit check only) • Deleted Thermal Cycle testing of Grid Box assembly • Postponed some operations until after delivery to I&T

  16. Key Schedule Issues (cont) • Problem: Late start on fabrication of X-LAT Plate Assembly • Impact: Delays X-LAT Plate delivery date to SLAC • Is: 12/9/04; Re-Baseline: 8/12/04 • Mitigation steps taken or planned to get back on schedule: • Lockheed performing preliminary design to draft versions • Interfaces to DAQ boxes and Grid were defined • Lockheed will be given permission to build the X-LAT Heat Pipes prior to the Manufacturing Readiness Review

  17. Approved Cost Changes Since Rebaseline • (k$) • 4.1.8 Baseline, November 03 $13,384 • Changes: • Align Schedule w/ Grid Deliv $ (22) • Grid Assy & TCS Replan $ 53 • Stanford Benefits Rate Increase $ 63 • Total Change $ 94 • 4.1.8 Baseline, February 04 $13,478

  18. Variances Cost variances: • LM = +$158K. Will be used in upcoming months • SLAC = -$57K. For contractor engineering support. Schedule variances: • LM = zero • SLAC = -$189K. Receive flight hardware for thermal control system (-$184K)

  19. Looking Ahead 6 Months • Grid #1 delivered to I&T • Supporting I&T integration operations • Grid #2 delivered to SLAC • Static Load Test preparations underway • X-LAT Plate fabrication complete and ready for test • Radiator fabrication 75% complete

  20. Summary • Major interface issues have been resolved in last 6 months • CAL – Grid, X-LAT – DAQ and Tracker - Grid • Designs are released (except X-LAT plate) • Fabrication of both Grids is underway • Fabrication of Radiators is underway • LM effort has ramped up significantly • No major issues with hardware fabrication • Focus now on resolving test issues • MECH is off of the LAT critical path

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