Desiqn Herita,qe andIntentional Adjustments TheRRSusedonL7hasbeenusedinavarietyofconfigurations forGPS,Landsat 6,A2100, andother LMSSC-built spacecraft withrigidpanelsolararrays. Parameters thatareintentionally adjusted include therestraint cabletension anddiameter, theorientation andfiringsequence ofthepyro-cutters, andthe material anddimensions ofthesplitwasher andsleeve. ForLandsat 7,launchvehicle designloads drovetheRRScabletension highenough torequire acablediameter of5.5mm(7/32inch).To compensate fortheadditional strainenergystoredinthesystem, theendfittingwasdesigned withtighter clearances--and aresulting higherfriction--to dissipate thegreater kineticenergy. Thefunctionality oftheRRSwasactually modified forLandsat 7intwoways,bothofwhichcontributed to theinitialdeployment failure. First,thefrictional dragforceintheshockabsorber wasraisedtoohighby theselection oftighterdimensions. Benchtestingearlyonshowed thehigherfrictionprevented endof travelshock,butitwasnotrealized atthattimethatfulltravelwasadesirable aspectofthedesign, so thatwasn'tabenchtestpass/fail criteria. Second, thefiringsequence wasmodified forwhatseemed like agoodreason: toaddress aconcern ofpanelracking incaseoneofthecornercableswasnotcutbythe primary cutters. Sothefiringoftheprimary cuttersonthetwocentralcableswaspurposefully sequenced AFTER boththe primary andredundant cutterswerefiredonthefourcornercables. Ironically, thissequence helped revealtwopartfabrication problems intheRRSwhichotherwise probably wouldhavebeenoverlooked. Thefiringofthecornerredundant cuttersentrapped theinadequately extracted cablesbeforetheyhada chance topulloutoftheway,whichprobably wouldhavehappened ifonlythelastpairofprimary cutters hadbeenfiredfirst.Aftertheseshortcomings werediscovered, itwasbacktothebenchfordesign changes andre-qualification testsatthecomponent level,explained indetaillaterinthispaper. Deployment MGSE Deployment Surface Originally, theL7deployment surface wasapitintheconcrete flooroftheLMSSC highbay.Self-leveling epoxywaspoured intothepit,smoothed outmanually, andlefttocure.Thiswasputinplaceseveral yearspriortotheactualneeddate.Whenthetimecametousethedeployment flooranddifficulties arose;variations overthesurface weremeasured tobeasmuchas+6.4mm(0.25in).Thismayhave beeninpartduetotheunwiseuseoftheepoxyfloorfortemporary storage, butitisnotknownforcertain thatanacceptance inspection wasperformed whenthefloorwasfirstpoured. Subsequent discussions withepoxyvendors revealed theflatness requirements werepushing thelimitsofthetechnology. Support Stands Eachpanelmovesindependently duringdeployment, sofourindependent support standsweredesigned tospreadouttheweightofthearraypanelsontofourlow-friction airpadseach.Formanyyearspriorto L7,thesamesquareairpaddesignhadbeenusedsuccessfully atLMSSC forantenna deployment tests onsmooth granitetables. Acompressed airleveling systemwasalsodesigned intothestandstoensure thattheyworked properly. Thestandsworked wellexceptthatontheepoxyfloor,therewasenough unevenness inthefloorsurface tohanguponthecorners ofthesquareairpads.Also,smallbitsofdirt andparticulates gathered moreeasilyonthefloor,requiring frequent wipedowns toprevent additional air padhangups. AirDelivery System Atrickyproblem aroselaterwiththeairdelivery system, consisting offlexible plastictubingstiffenough to handlecompressed airatabout100psi.Itwasfoundthatwithout verycarefulhandling, thetubingcould introduce lateralloadsintothefourfloating support standsthatwerenotinsignificant. Thelateralloads weremeasured withsmallforcegauges anditwasfoundthatonlywithgreatcarecouldtheeffectsonthe movements ofthepanelsbeminimized. Intime,itwasrealized thatachieving repeatability wasnotgoing tobeeasy,ifnotimpossible. Thisproblem wasneverfullyresolved. 217