Transcript 8. LAT Design Integration

GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
CDR/CD-3 Review May 12-16, 2003
GLAST Large Area Telescope:
Design Integration Overview
Lowell A. Klaisner
Stanford Linear Accelerator Center
LAT Chief Engineer
[email protected]
Document: LAT-PR-01967
Section 8.0 Design Integrations
1
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Design Integration Talks
This Talk
Chief Engineer
Lowell Klaisner
Second Talk
Mechanical / Thermal
Martin Nordby
Instrument Thermal Analysis
Jeff Wang
Third Talk
Document: LAT-PR-01967
Electronics / Flight Software
Gunther Haller
Instrument Manufacturing
Jerry Clinton
Instrument Structural Analysis
Youssef Ismail
First Talk
Thursday 1:30 PM
Section 8.0 Design Integrations
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GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
LAT Documentation Status
Subsystem Drawings
Subsystem
Anticoincidence Detector
Tracker
Calorimeter
Mechanical
Data Acquisition
Total for Instrument
Document: LAT-PR-01967
Total
100
87
210
69
135
Not Started
29
0
0
17
32
In Progress
24
14
20
52
21
Complete
47
73
190
0
82
601
78
13%
131
22%
392
65%
Section 8.0 Design Integrations
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GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Parts Qualification
• Materials and processes – Jeff Tice
Submitted
ACD
CAL
Elec
Mech
TKR
Total
97
48
24
114
57
340
SLAC IPO
GSFC
Pending
Accepted Approved
97
97
0
48
48
0
22
22
2
113
113
1
48
48
9
328
328
12
• Electrical Electronic and Electromechanical – Nick Virmani
•See talk Thursday at 2:00 pm
Document: LAT-PR-01967
Section 8.0 Design Integrations
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GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Peer Reviews
• Peer reviews held for all subsystems
• Reviewers were experts in the relevant technical areas from
GSFC, the aerospace industry, and science community
• General concurrence with the current design
• Identified technical issues that are being addressed by the
subsystem engineers
• This process of reviews is important to assuring a quality
design and, therefore, the success of the mission
Document: LAT-PR-01967
Section 8.0 Design Integrations
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GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Trades Associated With Interface Finalization
Internal Interfaces
Trade Topic
ACD and TKR survival
temperatures and impact of
black paint on TKR sidewalls
Radiator panel cut-outs and
top profile
Electronic box mounting
CAL bolted joint to the Grid
TKR to Grid thermal joint
Status
Study
Conclusion
Complete Evaluate impact of using high-emissivity black paint Black paint raises ACD survival temps, which increases
on TKR and ACD survival temps
margins at QT, while having little impact on TKR survival
temps. Also adds redundant thermal path for TKR
Complete Find balance between maximizig radiating surface Stepped profile was baselined. Area is maximized, while
area, structural stiffness of panel top, and
providing good access volume under the ACD. Panel
integration access to VCHP joints
stiffness is not significantly affected.
Complete Investigate hard-mounting the E-Boxes to the CAL Changed baseline to hard-mount to CLA, to simplify
plate, and making compliant thermal joints to the X- structural and I&T plans. Incorporated thermal straps into
LAT Plate
the X-LAT Plate for heat removal
Working Investigate alternate design implementations for the Test results of friction testing have been used to finalize the
bolted joint, and the impact of new grounding
design. Alodine surface treatment baselined, but electrical
requirements
testing has not been complete. Shear allowables and
margins still being worked
Complete Develop new thermal interface in response to
Cu thermal strap baselined. This improves thermal joint
changes in the TKR bottom tray design changes
reliability. Changes to Grid interface decreases integration
risk, at cost of increased time to bolt on straps
External Interfaces
Trade Topic
Status
Study
Effect of solar array properties Complete Evaluate definition of cold-case SA that is suitably
and view factor on LAT coldconservative for Spectrum, without driving LAT to
/survival-cases
higher survival heater power needs
Radiator panel size and
Complete Finalize Radiator size to work with Spectrum solar
location
arrays
LAT-SC flexure mounting
Working Develop a balanced interface design to attenuate
feature
loads into the Grid and make the joint more
accessible during Observatory integration
Document: LAT-PR-01967
Conclusion
Agreed-to SA parameters delineated in LAT-TD-00224.
Heater power allocations finalized in LAT IRD
Stay-clear dimensions and placement finalized, along with
cut-outs for solar array accommodation
Wing bracket base lined to reduce stress concentrations in
the Grid, whil providing a bolted joint with better access
from the sides. This cleans up the SC flexure design.
Impact of pin envelope requirements on EMI Skirt stayclear
is still in work
Section 8.0 Design Integrations
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GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Open Design Issues
• X-LAT Plate Design
– A recent design trade transferred the structural load of the
electronic boxes from the X-LAT plate to the calorimeter
plates.
– This results in a single function for the X-LAT plate -providing a thermal path from the electronics boxes to the
radiators and a thermal path between the radiators.
– Details of the flexible (in X&Y) thermal connection between
the plate and the electronics boxes are being worked.
• Calorimeter to GRID joint
– The baseline design of a friction joint carrying shear forces
was deemed inadequate. Alternate designs are being
pursued.
• Application Specific Integrated Circuit (ASIC) Design
– Not all of the designs are proven
Document: LAT-PR-01967
Section 8.0 Design Integrations
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GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Design Maturity
• All subsystems have been through peer reviews
– Details in each subsystem presentation
• ACD
– Design is mature and tested
• Open issues on the ASICs and FREE board
• Model testing well along – electronics module
environmental testing planned
• Mounting flexure design needs testing
• Tracker
– Design complete with adequate margins
• Open issues around the manufacturing details of the
MCMs
• Engineering model is in test – positive first results
Document: LAT-PR-01967
Section 8.0 Design Integrations
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GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Design Maturity (2)
• Mechanical
– GRID and radiator design mature
– Overall thermal control system well characterized
– X-LAT design at early stage of design
– 1X4 Engineering model in fabrication
• Data Acquisition System
– “The electronics design is sufficiently mature with many
improvements and optimizations that were prudent” – peer
review summary
– Detail designs in progress
• Spacecraft interface
– Working groups are resolving technical issues
– Spacecraft PDR last week
Document: LAT-PR-01967
Section 8.0 Design Integrations
9
GLAST LAT Project
CDR/CD-3 Review May 12-16, 2003
Design Integration
• Thermal, Structural and Electronic interfaces are defined
• LAT Thermal and Structural models are complete
– Analysis underway
• Open integration issues
– Thermal system design closure
– Structural issue closure
• CAL - GRID interface
• Electronics – X-LAT plate interface
Document: LAT-PR-01967
Section 8.0 Design Integrations
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