1. GLAST Large Area Telescope:
Gamma-ray Large Area Space Telescope
GLAST Large Area Telescope:
Mechanical Systems Peer Review
March 27, 2003
2.3 – Risk List
Marc Campell
SLAC
Mechanical Systems Mgr.

2. Topics
Agenda
Risk list

3. Risk Summary ID # Risk Rank Risk Description Risk 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 0002
Mech 307
Very 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)

4. Risk Summary ID # Risk Rank Risk Description Risk Mitigation Mech 0003
Low
CAL to Grid friction joint does not perform as designed. The critical joint properties (coefficient of friction and bolt clamping force) can not be directly verified before or after environmental test
EM testing of joint and FE model verification.
Maintain large design margins for joint load capability
 1) EM Test completed
2) FE Model Verification
3) Independent analysis complete
Mech 0004
Mech 321
Maturing spacecraft design may result in late changes in Instrument/SC interfaces; resulting in LAT design changes past I-CDR and associated cost; schedule impact
Identify priority of detailed I/T design tasks with Spectrum via ongoing working groups
(1) Identify key I/F's driving detailed design by Peer Review 26 March.
(2) Complete final Interface drawings by 28 March to support final S/C-LAT ICD release.
(3) Finalize CG and document of internal agreements 28 March.
(4) Develop and agree upon closure plan with Spectrum for all issue identified in (1), LAT CDR (28 April

5. Risk Summary ID # Risk Rank Risk Description Risk 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)
Mech 0006
Mech 541
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
Mech 0007
Mech 542
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

6. End of Section 2.3