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. marcc@slac.stanford.edu

Topics Agenda Risk list

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)

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

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

End of Section 2.3