ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
UseofNonSpaceQualified Parts Asacostsavings measure, non-flight qualified partswereusedbasedonexpected lifetime compared, availability schedule, andtheimpacttoothercomponents intheeventofafailure.Thenon-flight qualified components thatwereusedintheHITSgimbalwerethefollowing: theencoder, theoptocoupler LED,the harmonic drive,andthecrossed rollerbearings. Eachcomponent wasdetermined tobesuitable for different reasons. Asearliermentioned theencoder wasvacuum rated.Outgassing wasaprimary concern forHITSandthe vacuum ratinginsured nodetrimental outgassing fromtheencoder. However outgassing isonlyone factorinthedetermination thatthisencoder wouldwork.Thedifferences between avacuum rated encoder andaflight-qualified encoder relatetothepartsconstruction forwithstanding vibration andmore importantly forsurviving intheradiation environment ofspace.Construction datafromthemanufacturer concerning operational vibrations alongwithapreliminary analysis oflaunchvibrations determined that theencoder wouldbecompatible withtheinstrument. Expected instrument temperatures werealsowithin theoperational rangeoftheencoder. Themainfearinusingtheencoder wasthelifetime oftheencoder LEDduetoradiation degradation. Onceaagainagoodknowledge oftheexpected radiation environment alongwithmanufacturer's dataregarding theLEDshowed thattheencoder wouldlastfortherequired oneyearofoperation withamoderate possibility oflastinguptothegoalofthreeyears.Thesurvivability oftheencoder wasenhanced bybeingshielded insidetheencoder's steelcanister aswellasbyan aluminum outercover.Intheeventtheencoder should failredundancy wasbuiltintothegimbal by counting thestepsinputtothemotorfromfiducials asshowninFigure14.Thefiducials taketheformof microswitches andanoptocoupler usedasanopticalswitch. Theoptocoupler wasnon-flight ratedbutit wasamil-spec part.Justaswiththeencoder, datafromthemanufacturer wasusedtodetermine its suitability foruse.Cooperation fromthemanufacturer alsoaided inintegrating theharmonic drive. Figure14.Gimbal Position Sensing Redundancy TheHarmonic DriveSystems Inc.HIUC-25 seriesharmonic drive,waschosen fromitsratedstepsize, torquemultiplication, physical dimensions, andavailability. Aflightqualified drivediffersfromanon-flight qualified driveinthematerials usedforthewavegenerator bearing retainer, andflexspline; italsodiffers intherecommended method oflubrication. Adapting thiscomponent foruseinHITSinvolved redressing issuesinoutgassing andlubrication. Outgassing requirements involved replacing thebearing retainer fromonemadefromnylontoonemadefromphenolic. Testing wasdonetodetermining ifthedrivewould meetlifetime requirements. Ordinarily, acirculating oilbathisthepreferred method forlubrication ofthis drive.Theimpracticalities ofproviding anoilbathaswellasoutgassing requirements drovethedecision touseBraycoat grease asalubricant. Concerns bythevendor regarding theuseofBraycoat were addressed byperforming alifecycle test.Thetestproduced alifecycle estimate thatwasgreater thanthe expected number ofcyclesformission life.Thedifference inflexspline construction between flightand non-flight driveswasalsoaddressed bythelifecycle test. NASA/CP--2002-211506 226
Expediency andsizewerethemaindriversintheselectionofthecrossedrollerbearingused.These bearingswereoriginallyintendedforindustrialuseanddidnothaveashighaprecisionastheABEC7or ABEC9bearingsnormallyusedforflight.Thetolerances withinthebearingwouldstillkeepthe instrumentwithinitspointingsystemsbudget.Beforeintegrationintothegimbal,thebearingswerefirst cleanedoftheresidualmachiningoilswithethylalcoholinanultrasonicbath.Braycoatgreasewasadded tolubricatethebearingsduringuse.Theconcernaboutpressurebreakdown ofBraycoatwasnegatedby thelargesizeofthebearingsfortheexpectedload.Inaddition,thelowangularvelocitywouldnotcause detrimental heatingofthebearingarea.Unlikethepreviouscomponents thatwerejustifiedthough analysisandtest,theuseoftherollerbearingwasjustifiedthroughextremelyhighmargins. Conclusion Themechanisms usedforHITSweredesignedtosupporttheoperational performance requirements of theinstrumentbyprovidingthemovementnecessaryforcertainopticalcomponents andopticalsystems. Costandexpediency becamemoreofamajordriverastheinstrument developed whilethemore traditionaldriversasweight,andmomentum reducedinimportance. Productsdesignedforindustrialuse onearthshouldnotberuledoutwhencostandexpediency isamajordriverininstrumentdevelopment. Goodresultscanbeachievedifthedeficiencies innon-spaceflightqualifiedproductsarerecognized and amended.AlthoughvariousproblemsappearedincertainHITSmechanisms throughthedevelopment processnonewererelatedtotheuseofthesenon-space flightqualifiedcomponents. Solvingthe problemsinthesemechanisms didnotinvolveusingcuttingedgetechnology asmuchasusingalready existingtechnology innovelways. Acknowledgements TheHITSinstrument development wassupported bytheSERDP program andNavy'funding. Theauthors wouldalsoliketothankStephen Lockwood forThermal Systems design, theAerospace Corporation for analysis support andDonWoods fordesignsupport oftheHITSinstrument. References Dymond, K.F.,Wolfram K.D.,Budzien S.A.,Fortna, C.B.andMcCoy R.P."TheHighResolution Ionospheric andThermospheric Spectrograph (HITS)ontheAdvanced Research andGlobal Observing Satellite (ARGOS): QuickLookResults" Proceedings ofSPIE,vol.3818,137-148 (1999) 2.Samson, JamesA.,Ederer, DavidL.Vacuum Ultraviolet Spectroscopy. Academic Press(2000) 3.HIRAAS CDR(NRLandSTPinternal document) 4.HIRAAS PDR(NRLandSTPinternal document) NASA/CP--2002-211506 227
Design ofanEVA-Capable Four-Point Restraint System Armond Asadurian _,JimHammond., KazuoHamada _,Hiroshi Irika,do_:_, MichioIto+,MihoEndo+ Abstract Launch LockMechanism (LLM)isdesigned toprovide four-point restraint foralargeExtendible Maston theJapanese Experimental Module SpaceEnvironment DataAcquisition- Attached Payload (JEMSEDAAP).Themechanism provides misalignment-tolerant spring-loaded latching atallfourcorners ofthe square instrument package, usingasingleactuation point.Provision ismadeforoverride ofthe electromechanical driverbymeans ofEVA(ExtraVehicular Activity). Thesystem isequipped witha Backup Latching Mechanism (BLM)toensure positive restraint duringlaunchandreentry. Visualand electrical indicators areintegrated throughout thesystem forlatching andunlatching demonstrations and verification. Introduction Thispaperwillpresent anefficient method ofachieving four-point spring-loaded latching fromacentral actuation point,whileretaining fullfunctionality withEVAoperation. Theprincipal restraining force generated ateachlatching pointistracedbacktothemainactuation point,whereaMoogType2stepper motoractuator provides drivetorque. Thisactuator hasunpowered holding torquesufficient tosustain eachofthefourlatching pointsinasecurelatched condition, withsignificant margin. Atajointsafetyreviewboardheldbetween NASA,NASDA, NECTOSHIBA SpaceSystems, andMoog Inc.,itwasdetermined thattheunpowered holding forceofthemechanism, whichreliesonthemagnetic holding torqueofthepermanent magnet motor,isnotconsidered reliable, despite thelargeforcemargin. Thisdecision wasinfluenced partlybyconsiderations ofmanned launchvehicle safety.Tomitigate this condition andtoenhance overall safetyofthemechanism duringlaunch, anadditional EVA-operated Backup Latching Mechanism (BLM)wasintegrated withtheLLM.TheBLMiscapable independently of lockingtheoverallmechanism andisolating theactuator fromtherestofthemechanism. Four-Point Restraint System Thefour-point latching mechanism wasdesigned toprovide therestraint feature fortheJapanese space station module ofSEDA-AP Extension Mechanism Assembly. SEDA-AP consists ofJEMattached payload mainstructure, JEMPayload Interface Unit,Payload Attached Mechanism -Payload Unit, Grapple fixtureforRMShandling, Buselectrical equipment andmiscellaneous monitoring sensors including Newtron monitor sensor(NEM-S) attheedgeoftheextension mast. Theplatform, onwhichtheabove-mentioned instruments aremounted, isreferred tohereafter asthe NEM-S plate.TheNEM-S plateisdesigned tobelatched infourcorners usingtheLLM.Onorbit,the NEM-S plateisextended outawayfromtheSEDA-AP approximately 1meteronanextendable boom. Themonitoring instruments arethenactivated. Retraction oftheNEM-S plateintotheSEDA-AP main structure isfollowed bytheLLMactuation oftheLLM,resulting inalatched condition. *MoogChatsworth Operations, Chatsworth, CA **NECTOSHIBA SpaceSystems, Japan +NASDA, Japan Proceedings ofthe36thAerospace Mechanisms Symposium, GlennResearch Center,May15-17,2002 NASA/CP--2002-211506 229
TheLLMisdesignedtoprovidesynchronized latchingofallfourcornersusingasinglesteppermotor actuator.TheactuatordesignisbasedonastandardMoogInc.Type2design,whichisapermanent magnetsteppermotorof2degreestepangle,combinedwitha100:1ratioharmonicdrivegearreducer. Themaingearboxlocatedattheoutputoftheactuatorisdesignedwitha1:2(speed-up) gearratio.Ithas twooutputshafts,convertingtheactuatoroutputintotwoseparaterotatingoutputs.Doubleuniversal jointsattheendsofeachshaftaccommodate potentialmisalignment betweentheactuator/gearbox and thetwolatchblocks. Thelatchblocksarethetwomainassemblies oftheLLM,whichengagetheNEM.Eachisdesignedto houseasecondarygearbox,springloadassembly,ballscrew,andthelatchingmechanism. Actuator andEVAGearbox Assembly Theactuator isapermanent magnet stepper motorof2-degree stepanglewitha100:1gearratio harmonic drivefortheoutputdrive.Thisactuator isequipped withanEVAdriveinputasaredundant operating means incaseofactuator powerfailure. TheEVAinputisthrough astandard 11-mm hexagonal bolthead(standard EVAtoolinterface) ontheexterior surface oftheSEDA-AP module. TheEVAhexboltthatinterfaces withtheEVAtoolisontheendoftheaping-loaded gearbox inputshaft. Insidethegearbox, abevelgearismounted ontheshaft.Axialforceontheshaftengages thebevelgear withitsmating gear.Themating gearismounted ontheactuator motorshaft.rheforcerequired to engage thesetwogearsis1.36kg,whichiscompliant withtheNASAEVAoperating requirements. EVA operation isenabled whensufficient forceisapplied totheEVAbolttoengage thegears.Operation ofthe toolthenrotatestheinputshaft,andthemotorshaft.Thisresultsintheoperation oftheactuator without theneedtoenergize theactuator winding. The5:1gearratiooftheEVAgearheadproduces arotor speedthatis5timeshigherthantheinputspeedattheEVAtoolinterface. ThisallowsEVAactuation of thelatching andunlatching function withinthe10minute timelimitsetbyNASA EVAoperation guidelines. Figure3.Actuator Assembly andEVAGears NASA/CP--2002-211506 231
MainGearbox Themaingearbox inputcomes directly fromtheType2actuator output. Theinputmember isabevel gear,whichdrivestwooutputgearsonshaftslocated at120°apart.Theoutputshaftsareconnected to thelatchblocksthrough thearticulated driveshafts.Themaingearbox hasprovisions forinputfromthe Backup Latching Mechanism (BLM)whichwillbecovered inaseparate section. Theratiooftheinput geartothedrivergearsis1:2(speed up).Thegearshaftsallrotateonballbearings formaximum efficiency. Figure4.MainGearbox Connectinq Shafts Theconnecting shaftsmakethedriveconnection between themaingearbox andthelatchblocks. The connecting shaftsaredesigned withdouble universal joints,toaccommodate manufacturing tolerances andassembly misalignments. Figure5.Connecting ShaftswithUniversal Joints NASA/CP--2002-211506 232
LatchBlockAssemblies TheLLMincludes twolatchblockassemblies. Eachlatchblockassembly implements twoofthefour latching points.Eachlatchblockassembly consists ofasecondary gearbox, ballscrew assembly, the preloadspringassembly, lockingarms,Halleffectsensors, thevisualindicator assembly, andthelocking pins.Thelockingpinsinterface withthestrikeassemblies, whicharemounted ontheNEMSinstrument. RELEASED ---ENGAGING =,,FULLY ENGAGED ] .... i Figure6.LatchBlockAssembly Kinematics NASA/CP--2002-211506 233
Figure7.LatchBlockAssembly Secondary Gearbox: Eachsecondary gearbox isdrivenbyoneoftheconnecting shafts.Thesecondary gearbox provides a rotational change ofdirection fromtheconnecting shaftstoaballscrew located orthogonal tothe connecting shaftaxisofrotation. Thespeedrationbetween thesetwodrivecomponents is1:1therefore a 1:1setofmitergearisused.Thegearsaremounted onballbearings formaximum efficiency and accuracy. Rotation oftheballscrew bytheoutputofthesecondary gearbox produces linearmovement ofthemating ballnutassembly, required foractuation ofthelocking armsandforproducing thespringpreload needed forthelatching operation. Ballscrew/Ballnut Assembly: Theballscrew/ballnut assembly consists ofa15.9-mm diameter shaftwithathreadpitchof3.175mmand amating nut.Thescrewismadeof440Cstainless steel,andisdrylubricated withtungsten disulfide coating. Thenutassembly isare-circulating balldesign, withaninternal crossover tracktominimize the profileoftheassembly. Preload SpringAssembly: Thepreload springassembly isattached totheballnut nutassembly through asetofBelleville springs. Thenuthousing iskeyedtothepreload springassembly housing, preventing rotation ofthenuthousing inthepreload springassembly housing. Thistranslates therotational movement oftheballscrew into linearmovement oftheballscrew nutwithinthepreload springhousing. Thepreload springassembly consists of13Belleville springs assembled inseries. Thelargeforce-versus-deflection ratioofthese NASA/C P--2002-211506 234
springsprovidesthenecessaryspringforcewithinalimitedtravelrange.Thepreloadspringassembly housingisattachedtothetwolockingarmsthroughtwohingepoints.Thehingesaredesignedwith Nitronic60bushingsandA-286stainlesssteelpins.Thesetwocomponents aredrylubricated,withthe materialselectionbasedontheanti-galling characteristics ofthesematerialsunderthehighcontact stressesexistingatthehingepoint Figure8.Belleville Spring Assembly Figure9.Preload Spring Housing Assembly NASA/CP--2002-211506 235
TheBellevilleSpringsweremeasuredandforceversusdeflectionplotswaspreparedtoestablishthe requireddeflectionforagivenforce.Thesemeasurements weretakenfourseparatetimestodetermine repeatability ofthesprings.Theplotbelowdemonstrates thefirstandlastmeasurement andtheresulting variationarenegligibleforthisapplication. ........ JEM SEDA -Launch Lock Mechanism o_o Latch Box Assembly #2(RH Side p/nC50319-001) Belleville Spring Washer Deflection Versus Force 0.20 Ac.m ,-.0.15 o 0.10 0.05.................................. !................................................................... ......... :......... : .....;....... _........ i.... i....... i....... ::.... m : i i i : .................. _...................................... _........:....... _.......... : ................ 175 200 225 250 275 300 325 350 375 400 425 Force (Ibs) [--Reading #2--Reading #1] Readlng #1Reading #2 Force Pounds perLatch Point (Inches) (inch_s_ (pounds} ([pounds x8.55112) 0.088 0.085 200 855.000 0.113 0.111 250 1068.750 0.138 0.137 300 1282.500 0.150 0.152 325 1389.375 0.156 0.158 337 1440.675 0.161 0.162 345 1474.875 0.165 0.166 350 1496.250 0.190 0.189 400 1710.000 Locking Arms: Thegeometry ofthelocking armsyieldsan8.55:1mechanical advantage fromtheactuation hingepoints onthepreload springhousing assembly tothecontact pointsatthelatching locations. Eachlocking arm ismadeoftitanium, anditscrosssection isthatofanI-beam, forstructural efficiency andinorderto minimize thedeflection ofthismember underload. HallEffectSensors: Halleffectdevice(HED)sensors areprovided tosensetherequired preloaded latched andunlatched positions. Thepreloaded latched condition issensed byanHEDexcited byamagnet mounted directly on theballnut assembly. Asthemechanism output approaches itspredetermined preloaded latching position, andthelockarmsengage thestrikeassemblies, themagnet activates theHED,anelectrical signalissenttotheactuator, andthepowertotheactuator iscutoff.TheHEDsareadjusted tostopthe rotation oftheactuator oncethepreload isestablished. Theunlatch HEDisalsoadjusted toswitchofftheactuator oncetheballnutisfullyretracted andthe mechanism isfullyunlatched. NASA/CP--2002-211506 236
Figure10.HalleffectSensor Visualindicators: Visualindicators areprovided forvisualindication ofthemechanism statusinlatched andunlatched positions. Thevisualindicators arespringloaded totheirretracted positions, indicating theunlatched condition. Thesamebracket thatholdsthemagnets required fortheHEDsisalsodesigned toactivate thevisualindicator mechanism. Thevisualindicators areextended against thespringforceasthe mechanism isdrivenintothelatched position. Theextension ofthevisualindicators becomes visibleat theoutside oftheJEMmodule, serving asavisualconfirmation ofthelatch/unlatched statusofthe mechanism totheEVAastronaut. Locking Pins: Locking pinsareprovided ateachofthefourcorners oftheSEDA-AP foreachofthelatching points. Thesepinsarerecessed insidethelatchblockassemblies toavoidanypossible contact withastronaut spacesuitsduringdeployment oftheNEMSplate.ThepinsaremadeofA-286material andaredry lubricated withtungsten disulfide toprevent gallingduringengagement withthereceptacles located on thestrikeassembly. Thepinsarethemainloadbearing components ofthelatching mechanism inYand Zaxesinthelaunchenvironment. StrikeAssembly Thestrikeassemblies arelocated atthecorners oftheLLMandaremounted ontheNEMSplate.Each strikehasonemainrollerwhichisthecontact pointofthelockingarmwiththestrikeassembly andwhich provides theconstraint ofthelatching mechanism inXaxis.Threeotherrollersareprovided oneach latching assembly. Theserollersaredesigned tocorrect possible misalignment oftheNEMSplateduring theretraction operation. Thelatchblocksareequipped withlargerampstocapture andguidetherollers intoanoptimum latching position andtoengage thelocking pinsandthereceptacles. Thelocking arms arethenactivated andthemainrolleriscaptured andtheappropriate preload isapplied whichisreacted through thelockingpinsintothelatchblocks. NASA/C P--2002-211506 237
Adjustment ofthereceptacletopinengagement individually ismadeatthestrikeassemblybyshimming. Shimmingeachofthestrikeassemblies producesauniformpreloadoneachofthelatchingpoints.Strain gaugesaremountedonthestrikeassemblies toverifypreloadbymaterialstrainatfinalassembly. :._.i::o '.., -- ,.. --J o Figure 11.Locking PinCrosssection Backup Latching Mechanism Thebackup latching Mechanism (BLM)wasaddedtotheLLMasaresultofthesafetyreviewmeeting heldwithNASA, NASDA, NECandMoogInc.Thisdeviceisdesigned tobeanintegral partoftheLLM. TheBLMprovides anadditional latching meanstoensurethattheLLMmechanism willnotlosepreload andwillnotdisengage duringlaunchorreentry. Intheinitialdesign, theactuator magnetic detenttorque wastheprimary theonlyholding forcefortheLLM.Thiswasdeemed unreliable duetoitsdependency on themotormagnetic force.Further discussion ofthisissuewillbefoundintheLessons Learned section. TheBLMisdesigned tobeoperated viaEVAandisequipped withavisualindicator external totheJEM module andvisiblebyastronauts. TheBLMisalsocapable oflockingtheLLMregardless oftheactuator outputposition atthetimefullpreload isachieved. BLMoperation isbasedontheengagement oftworatchet gears.Oneoftheratchet gearsisdirectly mounted ontheoutputoftheactuator, andisfreetorotatewiththeactuator output. Themating gearis thelocking gear,whichisrotationally rigidandisdesigned toengage withthedynamic geartoproduce thebackup latching, thereby isolating theactuator fromtheloadpath. Thenon-rotating locking ratchetgearismounted onamechanism thatconsists ofarotating cam,rollers, baseplate,wavespring,andactuating arms.Theactuating armsofthismechanism arealsodesigned to operate asthevisualindicators. Thismechanism islocated insidethemaingearbox, withtheactuating rodsdesigned toprotrude through theSEDA-AP module wallsothattheyareavailable forEVA operation. Therearetwoactuating arms.Oneisusedtolockthemechanism bybeingdepressed down;andthe otherunlocks themechanism byalsobeingdepressed down.Thesetwoarmsareattached internally so thatwhenoneisdepressed downtheotherrisesandviceversa.ThestateoftheBLMmechanism is therefore continuously indicated. NASA/CP--2002-211506 238
Thesetwoactuationarmsaredirectlyattachedtoacamwhichiscentrallylocatedinthemaingearbox andisdesignedtorotateatthecenterpointwhichisabovethecenterofrotationo1theactuatorandthe dynamicgear.Thelinearmovementoftheactuatingarmstranslatesintorotatingmotionofthecam.The lockinggear,whichisequippedwithrollers,isdirectlyseatedonthecam.The(-amisdesignedwith ramps,androtationofthecamresultsinlinearmovementofthelockingratchetgearastherollersare forceduptheramps.Thislinearmovement ofthelockingcamisusedtoengageanddisengagethe lockinggearfromthedynamicgear. Designandsizingoftheratchetgeartoothisbasedontheworstcaseunlatchingloads.Toprovide infinitelockingresolution,thedynamicgearisdesignedwithonefulltoothoffreeplay.Thedynamicgear iscenteredtoafixedpositionbyacompression spring.Thisfeatureensuresthattheengagement requiresnomorethanonetoothdeflection. Thereforetheengagement ofthetwogearscanbe accomplished atanyposition. NASA/CP--2002-211506 239
Lessons Learned Designing spacehardware tobetransported tospaceinmanned vehicles suchastheSpaceShuttle, andtosupport manned missions suchasthespacestationrequires anewapproach. Thefracture criticality ofmaterials ishighlyscrutinized, andergonomic factors related tohuman engineering become criticalinthedesignoftheproduct. NASA's strictguidelines, whileensuring thatthemanned spaceactivities aresafe,efficient, andcaneasilyleavetheeffectofdrivingthedesign. Anoffsetting factoristhefactthatEVA-related requirements canalsoofferbenefits: Design ofunmanned space mechanisms traditionally hasbeendictated byperformance requirements, reliability, weightandspaceavailability. Human engineering hasnotbeenadriving factorinsuchdesigns. Mechanisms suchastheLLMwouldbeadequately defined bysimilar guidelines; however, therequirement fortheEVAmechanisms allowsforsomeoftheredundant mechanism normally usedinunmanned systems togivewaytootherrequirements suchas ergonomics andhumanfactorengineering. Safetyofthemechanism formanned flightisofutmostimportance whenthepayload isreviewed for security duringlaunch. Anunsafe payload isconsidered adirectthreattothe,safetyofthelaunch vehicle anditscrew. Themagnetic holding forceofanactuator, regardless ofthedemonstrated design margin, isnot considered areliable meansofsecuring payloads withinthemanned spacevehicle. Amechanically positive engagement isalsorequired asabackup foraddedsafety. NASA/C P--2002-211506 241
ElectronicsArea,  c;owave j ,iI_  ___ SolarPanel(6)  L/"N__ / --_, . 11 _,,._,Sund Figure1.MAPSpacecraft Deployed Configuration Thesunshielddeploys toadiameter of5.1m(200in)fromadiameter of2.7m(108in)inthestowed configuration, whichisshowninFigure2.Theentirespacecraft hasamassof840kg(1,850Ib). Restrain System Requirements Theprimary objective oftheSARRS wastosecure thesolarpanels andsunshieldinthestowed configuration forlaunchandground transportation, butallofthemaindesignrequirements weremet: 1.Consume lessthan20wattsofpowerinlessthan150seconds peractivation; 2.Allowthespacecraft toremain insidethelaunchfairingforupto45dayswithout servicing; 3.Release thesolarpanelsfordeployment within150seconds; 4.Design masslessthan4kg;and, 5.Complete SARRS development withinschedule. SARRS Confiquration: KevlarCordandThermal Knife TheMAPSARRS wasdesigned tomeetalltherequirements andaddress otherissuessuchasactuator cost,delivery schedule, abilitytotesttheflightcomponents, access torestraint components during stowage, andriskofpotential solarcelldamage duringdeployment. Therestraint portion oftheSARRS consists ofone3-mm(0.12-in) diameter Kevlarcord"assembly thatencircles thesixsolarpanels by resting ontwelve cordstandoffs. Therelease portion iscomposed oftwo,oneprimary andone redundant, thermal knives2.Thecomplete SARRS configuration isshowninFigure2. 1Type72,Ashaway LineandTwineManufacturing, Co. 2ModelR09686-407, Fokker Space,Sa. NASA/CP--2002-211506 244