ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
Troubleshootinq &Repair-TheAdvantaqes ofManned Operations Withtheobservation oftheanomalous dynamic motions duringdeployment, theground support teamsfor thesolararraydeployment switched intothetroubleshooting mode,andthebenefits andthedifficulties of themanned operations capability veryquicklybegantomaterialize. Thecapabilities thatwerefoundtobe themosthelpful, andthosefoundtobethemostcumbersome, inthisinvestigation andrepairare discussed inthefollowing paragraphs inthehopethatdesigners accustomed tothelimitations of autonomous operations present inmostspacecraft programs mightbenefitfromthisexperience should theytoobecome involved inaninvestigation similartotheSTS-97 solararrayanomaly. Onelimitation ofthevideocoverage ofthespacestationdeployment operations wasthatitwasavailable overonlyaportionofthedeployment. Asluckwouldhaveit,thefirstsolararraywasdeployed duringthe videoblackout portion oftheorbitwhereonlyaudiodownlinkwasavailable realtime.Theaudio commentary describing theunusual dynamic motions ofthedeploying arraywassufficient toputthe various facilities standing byforsupport intoatroubleshooting modeeventhough muchofthe commentary afterthemastextension portion ofthedeployment wasindicating asuccessful deployment ofthefullyextended solararrayblankets. Confirmation ofananomaly wasswiftandconclusive shortly afterrealtimevideowasreestablished andavailable tothesupporting facilities. Thevarious viewsand levelsofzoomandresolution available fromtheOrbiter videocameras wereusedtoinspect thesolar arrayandcouldclearlydistinguish theanomalous cables. Ifthiscapability werenotavailable (asisthe caseinautonomous operations), itwouldhavetakenmanydaysofanalysis anddeduction fromthe internal solararraytelemetry toreachevenamoderate suspicion thatacablehadjumped apulley.In contrast, theOrbiter's routinely available videoallowed aconclusive determination ofafailedcondition (slackcables) withinafewminutes oftheeventandthedetermination ofthecause(panelsticking) within afewhours.Inaddition tovideo,stillphotography withevenbetterresolution couldbeobtained of specific items(Figure 7).However, therealtimecapability andtheabilityforgeneral inspection provided bythevideoprovedtobemoreusefulthanstillphotography inmanyinstances. Figure7.Medium Resolution StillPhotography oftheDeployed Wing* (Notethatactualphotographs clearly resolve downtoindividual cables andsprings) Inaddition torealtimevideowhichwaslinkedtoeachsupporting facility, delayed downlink videoofthe fulldeployment wasmadeavailable. Oncethisvideowasprovided, thedesignteamcouldclearlyidentify theunexpected sticking ofthesolararraypanelsandtheresulting motion oftheblanket tensioning bar andcables. Multiple viewsandzoom levelswereavailable fromthevarious cameras and NASA/CP--2002-211506 176
Figure8.LocalViewonApproach toTension Mechanism Inspection* (Notethatactualphotographs clearly resolve downtorivetheads andindividual wirestrands) Arriving withthesepersonnel wereavariety oftoolssimilartothoseavailable ontheISSincluding appropriate glovesforusebytheastronaut whiledeveloping therepairprocedures. Collocation ofthese skilledindividuals withthedesigners knowledgeable ofthemechanisms andfullyrepresentative hardware allowed thecreation ofaprocedure withinonedaythatwouldreturnthemechanisms toacompletely nominal condition. Interestingly, thiswasforafailurethatwasatfirstbelieved tobebeyond the capabilities foreffective repair. Oneadditional notetomakeregarding theteammake-up wasthattheexperience levelofthemembers wascritical whenevaluating EVAoptions. Asdiscussed earlier, safetyissuesareveryimportant in determining acceptable EVAoperations. Theyarealsoverysubjective andopentointerpretation. Steel cablesandpulleys aretwoitemsspecifically onthelistofdangerous orunacceptable items,andthey weretheveryitemsthatrequired handling inordertofullyrepairtheTension Mechanisms. Having onthe troubleshooting teamanastronaut ofsufficient experience andrespect suchthatgeneral safety "requirements" couldbetailored real-time allowed thecreation ofarepairthatcouldfullyrestore the mechanisms toitsfulldesigncapability whilestillproviding fortheessential requirement ofcrewsafety. Witharepairprocedure nowinhandtheeffortsoftheteamturnedtotraining theOrbiter crewonthe procedure andcreating contingency procedures andcontingencies tothecontingencies incasethere weredifficulties withthebaseline repairplan.Thefirsttaskoftraining theOrbiter crewturnedouttobe easilydispatched withtheuse,onceagain,ofvideocapabilities. Avideotapewasmadeoftheastronaut onthetroubleshooting teamwalking through therepairprocedure onrepresentative hardware using representative toolsandgloves, andthevideowasthentransmitted totheOrbiter. Thevideoand associated writtenprocedures andtelecons allowed fullunderstanding oftheactivities withlittledifficulty. Thecontingency planning continued throughout theweekuntilthetimetheactualrepairoperations were NASA/C P--2002-211506 178
performed. Muchtothesatisfaction ofallinvolved,therepairoftheTensionMechanisms wascompletely successfully andrequiredonlyafewminuteseach(Figure9).Althoughthemultiplebackupoptionswere neverputtouse,theirdevelopment wasessentialtoensurethesuccessofthemission. Figure9.Nominally Deployed ISSSolarArrays* Troubleshooting &Repair- SomeIssuesinUsingEVACapabilities Inspiteoftheimpressive arrayofcapabilities described intheprevious section, therewereavariety of impediments inusingthesecapabilities totheirutmost effectiveness andefficiency. Although some barriers weretechnical innature, moreoftentheywere"self-inflicted" byorganizational orcommunication barriers. Thetwobarriers thatweretechnical innatureincluded thelimitedtimeavailable forlivevideodownlink andthelimitations inviewanglesandzoomofthefixedvideoandstillcameras. Bothofthesefallintothe category thatitishardtohavetoomuchofagoodthing.Thevideoprovided suchclearanddescriptive coverage ofthecriticaldeployment events andinspections thathaving suchdatarealtimeforeach criticaleventcouldverywellprevent anomalous orunexpected performance fromresulting inaspecific failure. Itcouldalsoprevent investigative inspections frommissing criticalitemsorwasting precious time byrequiring re-inspections. Although thetimingforavailable realtimevideodownlinkandtheprocedural limitations inrequesting itforspecific activities isprobably wellunderstood bythe"innercircle"of operations personnel, neither werewellcommunicated tothetroubleshooting teamatthesolararray designfacility. Furthermore, specific recommendations toperform activities suchasthesecond wing deployment withinthis"window" wereneither performed norspecifically rejected. Thefranticpaceofthe activities, complex nature ofthemission andtheneedfortightcontrol oftheOrbiter's activities all contribute totheneedforlimitations intheexercise ofthisoption. Thustheadvice tomechanism designers participating infutureinvestigations istobeawareofthevalueofthiscapability andrequest specific instructions orprocedures forhowitsavailability isdetermined orrequested. Similar advice is givenforunderstanding limitations indealing withotheroperational constraints thatmightbeusefulsuch aseclipse times,spacecraft orientations, attitude control modes, etc.Itshouldalsobenotedthatitis unrealistic toexpecttoquickly understand thefullintricacies oftheoperation ofavehicle ascomplex as NASA/CP--2002-211506 179
References 1.Johnson, MarkE.,BertHaugen andGrantAnderson "Space Station Freedom SolarArray Containment BoxMechanisms" 2_hAerospace Mechanisms Symposium, 18-24May1994,pp1-16. 2.AIImon, Curtis andBertHaugen "Space Station Freedom SolarArrayTension Mechanism Development" 28_hAerospace Mechanisms Symposium, 18-24May1994,pp123-128. NASA/CP--2002-211506 182
TheLightweight Deployable Antenna fortheMARSIS Experiment ontheMarsExpress Spacecraft Geoffrey W.Marks*, Michael T.Reilly*,Richard L.Huff** Abstract TRWAstroAerospace developed andbuiltanantenna subsystem fortheMARSIS (MarsAdvanced RadarforSubsurface andIonospheric Sounding) experiment onbehalfoftheUniversity ofIowa,who provides antenna andtransmitter totheNASAJetPropulsion Laboratory (JPL).Theantenna fliesonthe extremely weightlimitedMarsExpress spacecraft duetoreachMarsin2004.TheMARSIS antenna isan example ofalightweight deployable structure thatisdesigned purelyforthespaceenvironment. Because ofthis,anysignificant frictionordragthatwouldoccuronEarthwillprevent itsdeployment, anditslarge dimensions makeitimpractical todeploy inanytestfacilityonEarth.Theverification process hasbeen developed through theprogram anddynamic simulation hasbecome themostimportant verification tool. Thispaperwilldescribe theunique designoftheMARSIS antenna andprovide detailsofthetestand verification program. Introduction Thebasicdesignforthefoldable tubeusedintheMARSIS antenna experiment wasoriginally conceived foruseontheweightlimitedSounder Antenna fortheplanned NASAEUROPA Orbiterspacecraft. These launchweight limitsforcedthecreation ofacompletely newantenna element design thathasbeen namedtheFoldable Flattenable Tube1(FFT). TheMarsExpress spacecraft isalsomasslimited. Itwasdetermined thatusingtheFFTwouldfitwithin theMARSIS weightbudgetandallowtheexperiment tofly.Theantenna deploys fromitsstowage boxon thesidewall ofthissmallspacecraft toprovide capability foraverylowfrequency sounding radar.It deploys inMars'sorbitasa40-meter tip-to-tip transmit/receive dipolealigned intheflightvectoranda7meterreceive-only monopole inthenadirdirection. Thewholemechanical antenna, excluding thefeed electronics, weighs 7.1kg. ThegoaloftheMARSIS experiment, ajointendeavor between theUniversity ofRomeinItalyandJPL,is tofindwaterstratabeneath thesurface ofMarsandtostudytheMartian ionosphere. Background TheMARSIS instrument isalow-frequency ground penetrating radarsounder andaltimeter, whichuses synthetic aperture techniques andasecondary receiving antenna toisolateunwanted reflections. The operating altitudes ofMARSIS areupto800kmforsubsurface sounding andupto1200kmfor ionospheric sounding. Asimplemented, MARSlS consists oftwoelectronics assemblies andtwoantennas mounted onthe spacecraft. Inoperation, theMARSlS control electronics generates alinearfrequency modulated chirp, whichisamplified andthenradiated bythenadir-facing dipoleantenna. ThentheMARSIS switches to receive modeandthereturnsignalfromtheMartian surface isprocessed through boththedipole antenna andthesecondary monopole antenna. Themonopole antenna, oriented alongthenadiraxis, TRWAstroAerospace, Carpinteria, CA** University ofIowa,IowaCity,IA 1USPatent6343442, Flattenable Foldable BoomHinge Proceedings ofthe36thAerospace Mechanisms Symposium, GlennResearch Center,May15-17,2002 NASA/CP--2002-211506 183
supportrigswhilethedeployment motionrequiresaverylargearea.Variousmethodsforsupportingthis motionwereconceived butallprovedimpractical. Thenormalenvironmental testssuchasstowed vibrationandthermalcyclingarestraightforward. Thechallengeistotestthefunctionoftheantenna elementsafterexposure.Thepyro-releases canbefiredandthedoorswillbeforcedopenandthe compressed tubeswillejectthemselves fromthebox.Butafterthatpoint-unlessthereisazero-g environment -thetubehingesdonothaveenoughtorquetodeployandanysignificantfrictionwill preventdeployment. Theagreedmethodistoverifythatthehingejointwillalwaysunfold-thereisno frictioneffecttostopit-andverifythatitwillreleasefromthebox.Theremainderofverification is providedbyanalysis.AnADAMS(Automated DynamicAnalysisofMechanical Systems)modelwas constructed andtheindividualelementsofthemodelwerecorrelatedtotesthardware.Themodelverifies thedeployment dynamicsandtheinteractionwiththespacecraft. Asampleoftheoutputisshownin Figure5. TheDesign TheTubeElements Requirements: •Thetubesarerequired tomeettheminimum deployed frequency of0.05Hz. •Thelongdipoles mustmaintain atotaltipdeflection of20cmunderallthermal extremes. •Theexternal finishmustdissipate staticchargeandmustnotgenerate debriswhendeployed. Construction: ThetubesareaKevlarandS-Glass composite thatisspecifically laminated toprovide nearzeroCTE inthelongitudinal direction andtoprevent creepofthematrixinthestowed condition (thetubes remain compressed foruptotwoyearsonthetriptoMars).Thetubesarelaidupin3.0-meter lengths andthenITOcoated. Theyarethensortedforstraightness sothatthecombination ofthe sortedtubes,whencorrectly oriented, willachieve thestraightest possible finished element. The tubesarethenmachined tocreatethefoldpoints.Theindividual tubesarethenspliced together to formthecomplete element (Figure 7).Thespliceisdesigned toflexwiththerestofthetubewhen compressed intothestowage box.Although thespliceeffectively doubled thewallthickness, theuse ofaflexible adhesive allowed thehighdegree ofstraintobetolerated. Thetubeswerepunched withanumber ofadditional holestoprovide access toinstallandsupport theconducting elements. Theconductive wiresweresoldered intoaladderframesuchthat extensions totherungspenetrated thetubewallsandwerestakedinplace.Thatwaythelegsofthe ladderweresupported alongopposing wallsofthetube. TheStowaqe Box Requirements: Totakeadvantage oftheextreme lowweightoftheconducting elements alightweight stowage box wasrequired. Thedesignoftheboxwasquitechallenging. Thethreetubeelements mustbestacked oneontopoftheotherandmounted acrossthespacecraft wallasshownFigure1.Themonopole is abletoexittheboxandfirestraight out,soitcouldbecontained inafour-sided boxwithabackand lid.Theelements ofthedipolehadtoexitinthesamedirection asthemonopole butthenneeded to rotatethrough 90degrees, eachindifferent directions. Theendwallsoftheboxtherefore couldnot exist,compromising thestructure ofthebox.Theboxisalsorequired tosupport thelocalelectronics andmountinakinematical manner tothespacecraft sidewall. NASA/CP--2002-211506 185
Stiffnesscorrelationmeasurements weremadeonthecompletedflight-andqualification-tube assemblies astheyfloatedonawatertable.Thecalculations werealsocheckedusingaCOSMOSfiniteelement model.Thedataisusedtopreparethespacecraftcontrolsystemalgorithms. Launch Phase Thestowed antenna assembly wasevaluated forthepredicted launchsine,random vibration, acoustic andshockenvironments usingafiniteelement modelgenerated inCOSMOS/M. Whilenodetailed representation oftheflattened antenna tubeswasputinthismodel, theirmasswasdistributed proportionally through thestructural boxmodel. Preload stresses weresuperimposed onresultsofthe dynamic analysis forthedefined environments. Twopercent structural damping wasassumed forthis analysis. Infact,testresults indicated significantly higherdamping, whichvariedbyfrequency andload level. Transfer Phase Thetransfer phaseofflight,withtheantenna elements stillstowed, involved verylowmechanical loads, butsignificant temperature variations fromambient buildtemperature. Thestructure, whichincorporates design features toaccommodate thestresses resulting fromthedissimilar coefficients ofthermal expansion ofthebuildmaterials, wasagainevaluated usingaCOSMOS/M finiteelement model. Deployed Phase Thedeployed system wasevaluated usinganother COSMOS/M model. Frequency response and strength wereevaluated forthepredicted environment. Testing Asstatedabove,thetestprogram wasnon-conventional because ofthedifficulty oftestingtheextremely lightweight tubesinarepresentative manner. Thephilosophy followed wastodemonstrate thatthe components ofthetubewere100percent reliable suchthatifthedoorsopened itcouldbeassumed that theelements wouldfullydeploy. Itwasanaccepted factthetubeswereonlyabletofirethemselves onto aflattableasshowninFigure9.Thetestprogram hasqualified thehardware asfollows. Element Tests Thetubeelements weretestedtodemonstrate thefollowing properties: Hingeactuation reliability. Multiple operations ofsample hinges weremadeunderalltemperature extremes including inliquidnitrogen. Thetestsdiddemonstrate someproblems withtheinitialcutout configuration. Designmodifications weremade,arriving attheshapeshowninthefigures. •Hingetorque/rotation anglecharacteristics inallaxes-thisdatawasusedasaninputtotheADAMS analysis. •Tubelateralcompression stiffness -alsousedintheADAMS analysis. Tubeandtubesplicelong-term creepproperties undercompression. Tubesamples havebeenkept undercompression forupwards ofayearandhaveshownnosignificant loaddecrease. Tubestrength andstiffness havebeenmeasured forallrootconfigurations. Thetubestrength is reduced atthefoldcut-outs. Thenominal tubehasabending strength of17N-m(150Ib-in)with13.5 N-m(120Ib-in)withtheslotsintheneutralaxis,and0.58N-m(60Ib-in)whenrotated 90degrees. NASA/CP--2002-211506 187
Structural Model Amodelofacontainment boxforthelargertubeelement wasconstructed toprovethevarious functions. Itwassubjected torepeated deployments todemonstrate therobustness ofthetubeelements andthe wireinstallation. Itproved thefunction oftherelease system andthedoorenergy dampers. Itwasalso subjected tovibration testandthermal testing. Allfunctions weresuccessfully demonstrated. RadioFrequency (RF)Performance Model Oneoftheunknowns ofthewholeinstrument designwasexactly howtheantenna wouldwork.Toprove itsperformance twoofthe20-meter dipoles weredelivered totheUniversity ofIowa.Theywerebold enough toconstruct afieldexperiment inwhichthetwodipoles andarepresentation ofthespacecraft bodywereliftedfromtheground andsuspended vertically beneath ahelicopter. Thetestwascarried out inColorado wherethewholeassembly waslifted3000m(10,000 ft)abovetheground, looking sideways attheneighboring mountains. Theexperiment worked well,proving thefunction, andthewhole experiment wascarried outwithnosignificant damage tothefullyflightrepresentative hardware. The eventisshowninFigure10. Qualification Hardware Afullyflight-like assembly wasbuiltasshowninFigure2.Itwassubjected tothefollowing tests: Functional Test-Therelease functions andelement performance weredemonstrated. Theelements werereleased ontothedeployment tableinturn.Duringthistestcontamination samples weretaken toverifythatthetubesdidnotgenerate debriscontaminants. .Vibration Test-Theassembly wasmounted toavibration fixtureandsubjected tosineandrandom vibration environments. Thermal Vacuum -Theassembly wasthermal cycledinvacuum. Thesafetystraps(theredclamps showninFigure2)werekeptonforthistest.Thedoorswerereleased attemperature extremes duringthetestandthesafetystrapsprevented deployment ofthetubes. FinalFunctional Test-Thefullperformance oftherelease mechanisms andtubeenergy release was againtested.Thetubeswereagaindeployed insequence ontotheflattableandagainparticulates weremonitored. Theparticulate countwassmallandacceptable. Fli.qhtHardware Test Atthetimeofwritingthispaper,theflightassembly isalmostcomplete andwillbesubjected tothesame testsequence asthequalification hardware. Conclusions Thisprogram required newmethods tobedeveloped tovalidate thedesignandtoassure performance of flighthardware. Acombination ofanalysis andcomponent testwasutilizedtoaccomplish thisgoal. NASA/CP--2002-211506 188
Dipole#1 Pyro AssembliesTopPanel (Container Box) --Dipole DoorPanelsHingeLatchMechanism Monopole LatchPan--Dipole#2 SafetyStraps (RemoveBeforeLaunch) 9491 Figure2.MARSIS Antenna Stowed forLaunch withSafetyClamps inPlace NASA/C P--2002-211506 190
MABE: High-Precision Tip/Tilt Mechanism BasedonMagnetic Bearing Technology N.Loix*,J.Ph.Verschueren* andL.Scolamiero** Abstract Thispaperpresents a3degrees-of-freedom long-stroke, high-resolution tip/tiltmechanism forspace interferometric mission applications basedonmagnetic bearing technology. Abreadboard modelofthe mechanism hasbeendeveloped andsuccessfully passed environmental andfunctional tests.The translational androtational resolutions arerespectively 1nm(overa5-mmstroke)and10nrad(overthe two5mradrotation ranges). Thanks totheinnovative magnetic bearing design, thepowerdissipation in themechanism (under gravity compensated conditions) islessthan1mW,whichmakes itagood candidate forinfrared interferometric applications inacryogenic environment wheredissipated powerhas tobeminimized. Anin-orbit testdemonstration ofaproto-flight mechanism modeliscurrently under preparation, andistobeflownonboardtheSpaceShuttle GAScanister carrier. Thepresented activity hasbeenperformed withintheESAGSTPresearch program. Introduction Scientific satellites areincreasingly demanding inpointing accuracy andfuturemissions areexpected to require performances oneorseveral ordersofmagnitude betterthanthecurrent stateoftheart.The success ofthesemissions isclosely linkedtothedevelopment ofadvanced control techniques for disturbance rejection andmechatronic components capable ofmanaging largestrokeandveryhigh precision inthenanometer range.Previous studies [1,2]haveshownthatmagnetic bearing systems can perform thischallenging requirement. DuringtheMABEproject, abreadboard modelofalong-stroke, high-resolution tip/tiltmechanism based onmagnetic bearing technology hasbeendesigned, manufactured andsuccessfully tested. Thedeveloped mechanism has3-degrees-of-freedom (DOF),onetranslation (tiporpiston)and2rotations (tilt).Itcanbeusedtocontrol therelative motionofopticalmirrors forspaceInterferometers likeforthe GAlAinitialopticalconcept, ortheDARWIN infrared interferometer (bothESAprojects). Itcanbeutilized forspacetelescope applications aswell,where ahigh-accuracy alignment /pointing /refocusing mechanism ofsegmented primary mirrors orsecondary mirrors isneeded. Thepowerdissipation inthe mechanism hasbeensubjected tospecial attention andhasbeenkepttoaminimum thanks toan innovative magnetic layoutthatincludes permanent magnets. Careful selection ofmaterials allowsfor possible useinacryogenic environment. Themaincharacteristics ofthemechanism are: Thepayload isa1-kgdummy mirror(aluminum plate) •Number offunctional DOF: •Stroke: oPiston oTilt •Resolution: oPiston oTilt •Bandwidth: •Perturbation attenuation: •Guiding: •Powerdissipation inthemechanism:3(2rotations and1translation) 5mm +/-2.5mrad 1nmrms(RMSvalueofthemoving average over0.75s) 10nradrms (RMSvalueofthemoving average over0.75s) 16Hz 100dBat1mHz 1nmrms(RMSvalueofthemoving average over0.75s) <1mW i,Micromega Dynamics, Angleur, Belgium ESA/ESTEC, Noordwijk, TheNetherlands Proceedings ofthe36thAerospace Mechanisms Symposium, GlennResearch Center,May15-17,2002 NASA/CP--2002-211506 197