Multilayer Insulation Material Guidelines

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idelinesM.M.FinckenorMarshallSpaceD. DoolingD 2 hallAprilFlightSpace1999FlightCenter MSFC,Alabama35812Center,Alabama

TradeTradenot to implynamesare used in this guidebookendorsementNamesto illustrateby the U.S. Government.the use of variousThe tradenameslisted here. Trade names should be used only to describe specificexample, not all hook-and-pilefastenersare Velcro brand).commercialare the propertyproducts,materialsandof the companiesnot as genericterms(for3M Co.: Nextel, ScotchChemfab:Beta clothE.I. DupontKamende NemoursWipingMaterials,Inc.: Dacron,Inc.: nclothTexwipe Co.: Alpha 10 wipeVelcro USA, Inc.: Velcro, Hi-GardeAvailable from:National Technical Information Service5285 Port Royal RoadSpringfield, VA 22161(703) 487-4650NASA Center for AeroSpace Information800 Elkfidge Landing RoadLinthicum Heights, MD 21090-2934(301) 621-0390ii

TABLE1. INTRODUCTION1.1 ScopeOF CONTENTS.2.21.2 Purpose1.3 Applicability2. APPLICABLE.DOCUMENTS.4552.1NASA2.22.3U.S. Departmentof Defense.Other U.S. Government.52.4Other .63. GUIDELINES.3.1 Applicable3.2 Processing3.3 MaterialsDocuments7.Traceability4. SELECTION5.OF MATERIALS4.1 Standard Blanket4.2 Thread Selection.Layers .9144.3 Adhesives.154.4 Adhesive4.5 FastenersTape .16185. FINISHING.225.1 Seams.225.2 Billowing.5.3 Tie Downs .6. ENVIRONMENTALEFFECTSON MULTILAYERINSULATION.2323246.1 Atomic Oxygen .6.2 UltravioletRadiation.246.3 Meteoroid/Orbital6.4 Contamination2527Debris Impacts.Control .6.5 Outgassing.6.6 Plasma Effects .iii252727

TABLE7. OTHERCONCERNS7.1Electrical7.2InstallationOF CONTENTS(Continued).Bondingand GroundingRequirements.7.3 Venting7.4 CutoutsRequirementsor Protrusions7.5Storage.7.67.7Repair .Other Hazards.7.8Cryogenic8. VENDORSInsulation.iv28282829303030313132

LIST Schematiccrosssectionneed be presentThe interior.module.ShuttleColumbia'sand crew transfertunnelpayloadthe Shuttleorbiterfor up to 2 wk at a time,Experimenttraysorientationrelativeon the LDEFthe Huygensthroughso the MLIcoulda completepotatochecksvaryinginsidebeforedegreesthe vehicleis coveredwith the payloadin Betabay doorsof damage,is closedclothsinceopen .dependingcontrolledconditions.by coolingnose fairing.The MLIhad to be removed4.of MLIcomponentsT-shapedobjectsas they are assembledlatex gloves,to the rear are largehold MLI sets together.3air that was blownThe probeNote that she is wearing2on their69 mo in orbit .was damagedthe thicknessto gentlyaftervehicleinstalledeverythingeven underprobeassembly.glasses.chip bags)Titanthe launchblanketand safetydamagedbe repaired(a) A technicianshowedto the line of flight,and easilytoo quicklyNot all elementsbay is seen here with the Spacelab(left to center)Note that virtuallyflies,of an MLI blanket.design .for stacking.covering the key elementsand movedMLI is fragile.in everyof Space(right)depictsOF FIGURESplasticintoa hair cover,clips(the sameAlso note that blanketas formaterialsfartherback on the table are covered with bagging plastic. (b) Two technicians,also wearinggloves and face masks, hold a completedblanket. It includes hook-and-pilefastener strips.at top and right,and a tesyAO erosionlayersof Boeing)is readilystitchedcutoutare stitchedstrip, fromto makethe left side, for a protrusiona completeblanket.seen in scanningelectronmicroscope(a) before and (b) after exposureto AO. Note that the Teflonbut that the glass fibers remain intact. Samples of (c) KaptonTeflon.are shownMultilayerof a panelafter exposureinsulationusingis easilya sampleto AO on LDEEpenetratedof SpaceStationimages.22Beta clothcoating has been erodedand (d) silverized.by high-speedmaterials.debris,Lightweight,as in this ballisticslowerdebristestposesa greater hazard to MLI which can erode with long exposure,especiallywhen coupledwith AO and UV effects. These views cover a width of -15 cm (6 in.) .V2425

LIST,To protectpatchesareas wherethe MLI had degraded(b) to the exteriorservicingmissionOF FIGURESof the Hubble(STS-82).Such repair(Continued)in orbit (a), astronautsSpaceTelescopetechniques(c) duringwill becomeappliedMLI repairthe January1997more commonwith expandedoperation of long-durationspacecraftand the availabilityof humansor robots to maintain them .10.Electricalgroundingon spacecraftSpaceStation,11.the aluminizedinsert),polyimideand a metalstrap (fromBeta cloth-coveredout of positionare requiredthat may build up a static(the groundingto the groundstrapsa Boeingto groundcharge.In this designlayersare electricallyto the primarystructurefor the Internationalthrough.Shuttleconnectsby aluminumdrawing)bay door mechanism.the blanketconnectedgrommetMLI in the aft end of the Spaceby the payloadMLI layerspayloadThe underlyingfoilthe layers29bay was pulledspacecraftstructurewas not damaged,but the event highlightsthe potentialfor damagewith moving equipment .vi2631

LISToStandardblanketlayers,outerOF TABLEScover .102.Reflectorlayers edmultilaminate6.Threadsfor nonexposed7.Threadsfor exposed8.PSA tape, plain .169.PSA tape, glass fabric.17.17.innercover .innerMLIcoverseamsMLI seams13.13.14.1510.PSA tape, ingtapetapes.and tie cords.vii1821

LISTAOAtomicBOLBeginningof lifeEOIMEvaluationof OxygenEOLEnd of tOF ACRONYMSoxygenSpaceInteractionFlightSpacewith osureFacilityorbitDouglasAerospaceCompany(now part of Boeingand sStationand SpaceFreedomAdministration(now ISS)specificationspecificationixCo.)

IDELINES1. INTRODUCTIONIn general, multilayerinsulation (MLI) is a type of high-performanceinsulatorwhich uses multipleradiation-heattransfer barriersto retard the flow of energy. Individualradiation barriersusually are thinpolymerblanketfilms with vapor-depositedthat reflectsto a seriespercent100 percentof subblanketsof radiation.to fit complexThe cumulativeFor MLI to be effective,themmetalinto the spacecraft,on one or both sides. Becauseof incidentradiation,geometrieseffecta numberand assemblingan MLI design(fig. 1). Typically,is that of a nearlyof guidelinesit is nearlyimpossibleto designmay range from a few simpleeach reflector100-percent-effectivemust be followedwill reflect90 to 99barrier.in selectingmaterials,designingthe ment(Sectionof book in parentheses)Outer Cover (4.1.1)"/ ILight Block(if necessary)MetallizedReflector(4.1.2) [Netting Spacer (4.1.3)/ExposedThreads (4.2.2)AdhesiveTransferTape (4.4.1)Glass FabricTape (4.4.2)Nonexposed Threads (4.2.1)(15 to 20 d-PileConnectors (4.5.1)MetallizedTape(4.4.3)GroundingTape (4.4.4)MetallizedSeflector (4.1.2)Netting Spacer (4.1.3) IInnerCover (4.1.4)StructureNote: Detailsand featuresareshown for illustrationand will varywith actual designand installation.Figure1.SchematiccrossNot all elementssectiondepictsneed be presentthe key elementsin everydesign.of an MLI blanket.ablankets

1.1 ScopeThis o the spacesimulationsthe materialscan be usedenvironmentapprovedfor futureor shieldedof the space environmentfromas Spacelabof this documentthis documentdirecton variousexposure.Somedata on MLI materials2.The interior(right)for stacking.orbiter2of SpaceExposureare presentedShuttleand crew transferNoteColumbia'stunnelthat ty(LDEF)for informationused by previouswhethergatheredfromspacecraftsuch(fig. 3), and outlinespayload(left to center)everythingflies, for up to 2 wk at a time,bay is seeninstalledinsidebeforeis coveredwith the payloadotherconcernsonly. They can be used as guidelinesfor MLI designfor future spacecraftprovidedthe thermalrequirementsenvironmentaleffects on these materials are taken into account.FigurespacecraftspacecraftPurposeis to provide(fig. 2) and the Long-Duration(fig. 4). The data withindesignsare included.1.2The purposefor and used in previousMLIof eachnewdesignhere with the Spacelabthe vehiclein Betabay doorsopen.is closedclothsinceandthemoduleand movedtheShuttle

Figure3. Experimenttrayson the LDEF showedvaryingdegreesof damage,dependingon their orientation relative to the line of flight, after69 mo in orbit.

Figure4. MLI is fragile and easily damagedeven undercontrolled conditions. The MLIcovering the HuygensTitan probe was damagedby cooling air that was blowntoo quickly throughthe launchvehiclenosefairing. The probehadto be removedsothe MLI could berepaired.1.3 Applicabilitysources,This documentand availablebe availablepreference,that will performeitherspecifications,of-sightexpressedeach essfully.or implied,Thisdocumentconcerningoptics,givesno recommendation,andrequirementsMSFC-SPEC-1443.of NHB 8060.1C,and lists materialsused, with specifications,i.e., other MLI designs and materialsmaymaterialsmust meet the outgassingto sensitiverequirementsvarious approvedMLI designsThe data are not all-inclusive;vendorsof SP-R-0022AMLI blanketsbut may be testedused.endorsement,Regardlessand, if involvingmust be testedas an assemblyratherorof vendorline-for flammabilitythan e designeroften containand shouldthe latestbe takenmanufacturer'sas typicalshould review vendors'latestmore data than are presentedfrom new spacethe data listed.4possible,missionsas they are flown.specificationsare used.and not used in writingcatalogsand specifications,here. Further, the designerNASAis not responsibledesignTheseare subjector assemblyto changespecifications.which are updated frequently,andshould take into accountlessonsfor typographicalor othererrorsin

2. -527MaterialsNASAComputerwith ramImpactDamageList for SpaceWeld Procedureto Predictto the SpaceHardwarefor MultilayerOutgassingMSFC-STD-506Optical Surfaces in a Space EnvironmentMaterialsand ProcessesControlNHBFlammability,Test for Non-MetallicMaterialsOdor and Offgassingfor Materialsin EnvironmentsRequirementsthat AVacuumTM-100351ApplicationMaterialSelectionon Spacecraftof PolymericGuidelinesto Limit AtomicTM-104748Beta Cloth DurabilityInsulationBlanketOrbitalDebrisand ObservationMIL---C-20079Cloth, STD-970StandardsMIL-T--43636Thread,in Low EarthAssessmentCoversTape, Textileand PlasticHookFED-STD-209BCleanRoomL-P-377(No title given)Surface)and Planetary)Materialfor SpacecraftOxygenEffectsSheets,Otherand Workfor SpacecraftOrbitStationFreedomMulti-Layerof Defenseand Thread,Glassand Wire-Reinforcedand Pile, SyntheticPolyesterNon-melting2.3and Test ProceduresModelfor SpaceGlass;and Specifications,Nylon,with SensitiveCombustionEnvironmentU.S. atedBlanketsto 4438060.1Cthe ThermalOrderand Polyimideof Preference(Typicallyreplacedfor the Selectionofby A-A-50195)U.S. t5

e Resistivity of MaterialsThicknessof Solid aringASTM-D--3330Peel Adhesionof Pressure-SensitiveTape at 180* AngleA S TM-D--Peel Adhesionof Pressure-SensitiveTape1000of Salt Sprayfor TensileStrengthPropertiesof ThinPlasticSheetingof WovenFabricsby the Tongue(SingleRip) MethodUsed for Electricaland ElectronicApplicationsASTM-D-4030Glass Fiber Cord and Sewing ThreadTest Method for Emittanceof SurfaceASTM-E---408ASTM-E---490ASTM-E-595Solar Constantand Air Mass Zero Solar Spectral IrradianceTablesStandard Test Method for Total Mass Loss and CollectedVolatile E-5213SpecificationESA HandbookReportHDBKMILMilitary SpecificationNASA HandbookPROCProcedureSPSTDNASA SpecialStandardTMNASATechnicalMemorandumFilmMLIand MaterialsEnvironmentand TransmittanceSpheresfor PolyimidePublicationm a VacuumReflectance,Space Agencyfor TestingNHBfrom OutgassingAbsorptance,Standardsof SurfacesUsing

3. GUIDELINES3.1Definewheneverand controlpossible.970, exceptSelectthat NASAmaterialsApplicableand processesU.S. GovernmentdocumentsAll materialsDo not handleshall be consideredused in makingmaterialspull or unnecessarilyuntil after launch.betweenfirst in the orderor exposematerialsspecifications,in accordanceor standardswith MIL-STD-of precedence.Processingan MLI blanketwith bare handsdrawings,specificationsshall be treated(fig. 5). This requirementwrinkleextendsthemas flight- or program-criticalto all vendorsto uncontrolledor corrosivethe layersand lead to defectsas this may stresshardwarein the manufacturingchain.environments.Do notthat do not appearSeparationof the radiation barriers is maintainedby lightweight,low-thermalconductivitymaterialsthe reflectors.Avoid tautnessof the MLI blankets.MLI requiresan atmosphericpressureof 10 -5 torr to preventthe conductivityMLI blanket'sconvectionof the MLIand gas conductionquicklyrevertsbetweento approximatelyradiationbarriers.the conductivityAt pressures 10 -5 torr,of air, thus degradingtheprotection.3.3Considertreatedby engineeringand industry3.2from the time they are receivedDocumentsorganicaccordingly.of manufacturematerialsTraceabilityor receiptusedMaterialsin the he assemblyand assemblythe storageof the completeof MLIand handlingas age life-limitedconditionsfromandthe itemvehicle.The designerwill ensure, by way of a MaterialsUsage Agreement(MUA), that materialsused inthe fabricationof MLI blanket hardwaremeet all of the spacecraftmaterialsrequirementsby consideringthe nonoperationalof the candidateand operationalrequirementsmaterials,and total programlimited to, nonoperationalultraviolet(UV) radiation,transportation,selection.storage,In nylhandling,and spacecraftPolyesteron-orbitfall into two broadare applied.Fiberglassapplication,design engineeringThese requirementsinclude,and operationalthermallimits, loads, fluid environments,chargedelectricalbonding and grounding,contamination,and life expectancy.MLI materialscoatingsfor the particularcost effectiveness.wovenThe primaryclothor PET (Mylar),conditionscategoriesmaterials(andwill also be consideredof base rtiesbut are notparticles,Groundmaterialsand organic,toare:(Beta cloth)polytetrafluoroethyleneor PFTE (Teflon),polyimide(Kapton),or PVF (Tedlar).7

(a)(b)Figure5.(a)A techniciana completeandsafetypotatobackthebags)T-shapedto gentlytablethicknessandfacemasks,andright,andof MLINoteobjectsholdare coveredat nchecksblanketMLIwiththatto thesetsstitchedis wearingreartogether.bagginghold a completeda arenoteas theylatexplasticfromclipsthat blanket(b) TwoIt includesstrip,areassembledgloves,a eftside,samefastenerforintocover,as forfartherwearingstripsa protrusion

4. rsCoveroutergeneration.OF MATERIALScoverOutermaterialwill be resistantcover materialsas a light blockdirectlyto shedding,that are not opaqueunderthe outercoverflaking,to UV radiationandotherformswill have a metallizedwith no separatorlayer. Outercoverof particulatereflectorlayermaterialswhichare aluminizedwill have the aluminizedside facing the interior of the blanket. Peel tests should be specifiedsince aluminizedBeta cloth can lose its metal coatings with light handling. Where external optical propertyrequirementsapprovalcannotbe met with thesefor an alternativesystemsdamage,blanketlayerscovera conductiveare shownlistedmaterial.coatingin n MUAdischargebe evaluatedwill be submittedmay resultfor an outercover.in spacecraftTheouterto obtainelectroniccoverstandard1.A tight weave is essentialfor long-termdurabilityof Beta cloth in atomicoxygen(AO).TM-104748contains data on the failure of a looser weave Beta cloth (SheldahlG414500)to protectNASAunderlyinglayersnot exposedfrom AO attack.weaveBeta clothmay be acceptablefor use in spacecraftareasto AO.Prolongedmethylsiloxanebe used,Looserexposureto UVagent is used duringdependentradiationmayprocessing.on flexibilityincreasethesolarLess or a differentof Betaclothof Betaadditiveclothif aaltogetheris recommendedmaywheremaintenancein vacuum,of optical propertiesis essential,by an exposurewhich is sufficient to start the yellowingprocess.of 500 equivalentSun hours to UV radiationIt is essential that the UV radiationtesting ofBetabe performedbleachingclothThis testingsolar oughreflectoris heavilyattackedseams. DesignersBoth terms referatmosphericclothto be exposedmay cancelto AO on orbit,out any effectof UV.since AO will maintainthebleaching.layers need an outer coverby AO, reducinglayersis criticalare not perforated,otherwisefor BetaLayersfor the reflectorplacementin vacuum,may not be necessaryto be perforatedfor spaceleavingopticssomefor protectionthe effectivenessto allowapplicationsventingto preventareas of the blanketunsewnfrom space environmentof the insulation.duringcontaminantascentmany patterns,hole sizes,may allow enoughand hole densitieseffects.OrganicMLI blanketdesignsto preventdeposition.will find referencesto perforationand porolation(pores)to holes in the reflectorlayers, made either by a ngballooning.VentIf the reflectorlayersthroughthe blanketin manufacturers'data sheets.(perforation)or a hole punchare available,no dataare listedhere on9

Tableldaterial1. cificationRk.MB0135-027 Rk.MB0135-027Descriptionwith Kapton,transFiberglasswoven Fiberglasswoven eaveNomex parentindiumtinwithPTFETeflon withPTFETeflon bondedoxideconductivew/polyester(500F:nosilicone) withonesideadhesive,oneside dorsChemfabTeflon,BackedTollon,Coated& BackedFEPTeflon,Teflon,transparentvacuumdeposited indiumtinoxidesilverandInconel kingChemfab,Ounmore Sheldahl,Dunmore avePlainPlainTexture,warpxfill,yamgcm( n.) 00(104(0.00016) 0.00004(0.00016)N/A! NIAN/A0.01(0.004) 20% -Elongationat break,% nge,"C(1:)Continuous,min/rnax 204(400) 72/107(-100/225)Intermittent,rain/max 112][31Environmentalcompatibility arabsorptance,andinlraredemissivitylot coversofvaryiq thicknesses[1]KaptonThicknesscm(mil)i(I.011o bi2.mI. .034) 0A10.0036(0.66) 0.44O.0071(0.131) 0.490.011(0.20)0.510.019(0.34)0.54[2] [3]Teflon,coatedgrWcm2(Ib/yd2) .011(0.20) 0.600.027(0.50)0.750.02710.50) 0.750.055(0.75) O.SOO.OGG(1.01)0.85

Alsoachieveto be consideredthe desiredgenerallythermalin designingeffectuse 15 to 20 reflectorThe metallizedsubstratecoatingshall be 99.99 percentadhesion.discoloration.Discolored71). MinimizescratchingTable 2 showsblanketsurface.The coatingareas will be evaluatedof the metallizedthe differentpure metal,Specificationmanyreflectorlow-Earthlayersare neededorbit (LEO)film duringreflectorAluminizedKaptonMDAC-STM0691,i Type II, Class 1,GradeAvacuum-depositedwill be uniformlayerswith a brightfor emissivityblankettospacecraftlayuponto the polymermetallicstandardsfilmcolor and free from(use ASTM-E408-and handling.and their characteristics.Table 2. ReflectorMaterialis howLong-termlayers.with satisfactorysignificantan MLIon the ptonRockwell MB0135-038,TypeII, Class1,GradeATeflonMDAC STM0691,Type II, Class 1,Grade ASingleor doublealuminizedSingle or doublegoldizedDoublealuminizedSingle or doublealuminizedSingle or doublealuminizedVendorsSheldahl, DunmoreSheldahlSheldahl, DunmoreSheldahl, DunmoreSheldahl, DunmoreThickness,mm (mil)metal,A0.0076-0.127 (0.3-5.0)1,0000.0076-0.127 (0.3-5.0)7500.0051-0.127 (0.2-5)1,0000.00006-0.00130.00003-0.0013(0.25-5); 300(0.1-5); 30026o(5oo)260(500)DescriptionWeight,gm/cm2 (oz/yd2)0.0051 mm(0.2 mil)0.0064 mm (0.25 mil)0.0076 mm (0.3 mil)0.013 mm (0.5 rail)0.025 mm (1.0 mil)0.051 mm (2.0 mil)0.076 mm (3.0 mil)0.127 mm (5.0 mil)0.0011 (0.020)0.0019 (0.034)0.0036 (0.066)0.0071 (0.131)0.011 (0.20)0.019 tent,max/min-250/ 288 (-420/550)-250/ 400 (-420/750)-250/288(-420/550 )-420/750 (-250/400)-250193 (-420/200)11]-250/150 (-4201300)Absorptance,a (max/typ)0.14;0.120.30; 0.280.14;0.12 0.14 0.14Infraredemittance,e0.05;0.03[210.04; 0.02 [210.05; 0.03 131 0.04 0.040.0007 (0.013)0.00093 (0.017)0.0011 (0.020)0.0019 (0.034)0.0036 (0.066)0.0071 (0.131)10.011 (0.20)0.019(0.34)i 0.0017 (0.031)0.0033 (0.060)0.0066 (0.12)0.0104 (0.19)0.0175 (0.32)Typicalemittancefrom noncoatedside[1] Temperaturerangefor double-aluminized Mylarmay be limitedto 120 "C(250 "F) dependingonsensitivityof blanket design toshrinkage.Shrinkingtheblanketbe

polymer films with vapor-deposited metal on one or both sides. Because it is nearly impossible to design a blanket that reflects 100 percent of incident radiation, an MLI design may range from a few simple blankets to a series of subblankets to fit complex geometries (fig. 1). Typically, each reflector will reflect 90 to 99 percent of radiation.

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