GLAST Large Area Telescope:

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GLAST Large Area Telescope Tracker
Subsystem WBS 4.1.4 2D Mechanical Design and
Status Overview Thomas Borden Stanford Linear
Accelerator Center Tracker Subsystem
Engineer tborden_at_slac.stanford.edu
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Agenda

• PDR Design
• ART Status
• Bottom Tray Redesign
• CDR Design
• Design Requirements
• Documentation Status

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PDR Design

• PDR structural design documented in
  HTN-102070-0002, based on GEVS appendix A, Delta
  II
• Vibration level drive design
• Acoustic and shock are under vibration level
  envelope
• June 01 Peer Review and January 02 LAT PDR
• At PDR the design philosophy was to use limited
  analysis with prototype testing to verify
  acceptability
• In February new vibration levels received from
  the Project Office
• General GEVS level
• Prior to first Prototype Vibration Test
• Difference is full spectrum at 50 Hz for general
  GEVS vs. 300 Hz for Delta II
• Official launch vehicle change from Delta II to
  Delta Heavy spring 2002

19 Carbon-Fiber Tray Panels
Carbon-Fiber Wall
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ART Status

• Anomaly Review Team (ART) convened by IPO in June
  after second prototype vibration test.
• ART committee report, LAT-LR-00870-01, summarizes
  findings and lists recommendations
• Implement the corrective action plan proposed by
  the Tracker Team
• Conduct evaluation of failed parts to ensure
  expected material strength was achieved
• Strengthen the development of process controls
  during this phase of development
• Tracker Team should develop and maintain a list
  of uncertainties and mitigation strategies
• The LAT IPO should conduct an EM Production
  Readiness Review prior to Engineering Model
  fabrication
• The formal Anomaly Review Committee should be
  released pending closure of open action items

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Bottom Tray Redesign

• Several design variations have been pursued
• All metallic closeouts Invar, rejected - Invar
  is magnetic
• Titanium corner joints in Carbon-Carbon
  closeouts, insufficient strength margins in
  closeouts
• Titanium corner joints in Carbon-Carbon/M55J
  composite closeouts
• Titanium corner joints with Carbon-Carbon/M55J
  composite closeouts chosen
• Draft drawings complete
• All materials on hand, fabrication imminent

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CDR Design

• Based on the following specifications
• LAT-SS-00778, LAT Environmental Specification
• LAT-SS-00138, Tracker Mechanical/Thermal
  Interface Specification
• LAT-SS-00176, Tracker Electrical Interface
  Specification
• LAT-SS-00134, Tracker Subsystem Level-IV
  Specification
• The Tracker is fully compliant with these
  specifications

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Documentation

• All Drawings released or in release cycle
• All specifications released or in release cycle
• Released processes and procedures for items in
  fabrication and draft versions for items not yet
  in fabrication.
• PRR held for ladder assembly, production began
  12/1/03
• PRR scheduled for tray assembly
• Web site has copies of all drawings and
  documentation.