Re-entryanalysis for the ATV with SCARAB Draft Final ...emits.sso.esa.int/...RD3-FinalReport-ATV-Re-entry-Analysis-SCARAB.pdf · Re-entryanalysis for the ATV with SCARAB Draft Final

Re-entryanalysisfor theATV with SCARAB

Draft Final Report

Issue2

ESOC/ESTECContractNo. 13946/99/D/CS

B. Fritsche,G. Koppenwallner, T. Lips

HTG Hyperschall-TechnologieGottingen,Max-Planck-Str. 19,37191Katlenburg-Lindau,Germany

ESA TechnicalOfficers: J.Monreal,ATV ProjectH. Klinkrad, ESOC

EuropeanSpaceAgency. ContractReportThework describedin thisreportwasdoneunderESAcon-tract. Responsabilityfor thecontentsresidesin theauthorsor organisationsthatpreparedit.

Katlenburg-Lindau,August2001

2 Re-entryAnalysisfor theATV with SCARAB Draft Final Report

Contents

1 Intr oduction 3

2 Modelling 4

2.1 Themodellingconcept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.2 Thegeometricandphysicalmodelof ATV . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.3 Massbudgets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3 Re-entry Analysis 13

3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.2 TheInitial Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.3 Re-entryAnalysisfor theNominalCase . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.4 Re-entryAnalysisfor theNon-NominalCase . . . . . . . . . . . . . . . . . . . . . . . 24

4 Fluids and Tanks 32

4.1 Tankmodelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

4.2 NominalRe-entry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

4.3 Non-nominalRe-entry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

4.4 Discussionof Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

5 DetailedDebris Characteristics 42

5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

5.2 NominalCase. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

5.3 Non-NominalCase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

References 95

Re-entryAnalysisfor theATV with SCARAB Draft FinalReportIssue2 3

1 Intr oduction

This reportpresentsthe resultsof a re-entryanalysisfor the ATV with the softwaresystemSCARAB[1–5] (S/C AtmosphericRe-entryandAerothermalBreak-up).TheATV (AutomatedTransferVehicle)will serveasasupplycargoandwastecarrierfor theInternationalSpaceStationISS.After deliveryof itscargo andpicking up thewaste,it shallperformadestructive re-entryover theSouthernPacificOcean.

There-entryanalysiswasperformedfor two cases:

1. Nominalcase:ATV missionnominal:Up-cargo deliveredto theISS,down cargo (duringre-entry)is madeof ISS’swasteandpropellantresiduals.

2. Non-nominalcase:Contingency casewith no ATV dockingto theISSperformed:Down-cargo (duringre-entry)is theup-cargo plannedatdockingtime,includingasignificantamountof propellants.

A re-entryanalysisfor agivenspacevehiclewith theSCARAB softwareis carriedout in severalsteps:

1. A modelof thespacevehicleis created.Themodelcontainsall geometricandphysicaldataneededto run there-entryanalysiswith thedifferentanalysismodulesof SCARAB,whicharea) Flight dynamics,b) Aerothermodynamics,c) Thermalanalysis,d) Structuralanalysis.Themodeldefinitionfor theATV caseis describedin chapter2.

2. Initial conditionsarespecifiedfor thedifferentanalysismodules,like trajectoryandattitudecon-ditions,andthesurfacetemperature.

3. Startingfrom the initial conditionsthe re-entryhistory is computed,until a disintegrationeventoccurs,generatingtwo or morefragments.For eachof thefragmentsthere-entryhistory is com-putedindividually, eitherup to thenext disintegrationeventor until thefragmenthits theground.In chapter3 the computedre-entryhistory is summarized.In chapter5 all computedfragmentsarecollectedin a list, containinga pictureof the fragmentandcharacteristicdata,e.g. time andaltitudeof generationanddisintegration,mass,materials,size,andgroundimpactvelocity.

Chapter4 presentsaspecialanalysisof thedifferenttanksonboardtheATV. Tanksareyetnotmodelledasspecificentitiesin theSCARAB software. Chapter4 containstheresultof a ’post-flight’ analysisofthetankpropertieslike temperatureandpressurewith aseparatetankanalysismodule,which is goingtobeincorporatedin a futurereleaseof SCARAB.


2 Modelling

2.1 The modelling concept

Thefirst stepin preparinga re-entryanalysiswith theSCARAB systemis theconstructionof a space-vehiclemodel.SCARABusestwo typesof models:

� ageometricmodel,containingall geometricdimensionsof thespace-vehicle,

� a physicalmodel,definingadditionalphysicalpropertiesof thespace-vehicleparts,e.g.materialsandmassproperties.

For thetwo casesto beanalysed(nominalandnon-nominal),two differentspace-vehiclemodelshadtobedefined.A detaileddescriptionof themodelsusedis found in thereporton theATV Modelling [6].Exceptfor someminor differencesin theinterior details,regardingthecargo, thegeometricmodelsfornominalandnon-nominalre-entryarethesame.

Figure1 shows a sketchof theATV with its maincomponentslabelled.Theoverall dimensionsof thecompleteATV includingthegeometriccoordinatesystemareshown in Figure2.

The geometricmodel is constructedfrom elementarygeometricshapescalledprimitives. Thereare6typesof primitivesavailablein SCARAB(version1.5): circle,rectangle,triangle,cone,sphere,andbox.They arecharacterizedby shape-specificparameters,e.g. inner andouter radiusfor a circle. For allprimitivesa wall thicknessis defined.Thus,a circle with finite thicknesswill appearin thegeometricshapeasa disk. TheSCARAB geometrymodulegeneratesa triangulargrid of panels to representthegeometricsurface.

Primitivescanbegroupedtogetherto build a compound. Compoundscanbegroupedtogetherto buildcomposedcompounds.In thiswayahierachyof complexity is built upduringthemodelcreationby theuser. In thepresentcasethetoplevel compoundwasthecompleteATV.

The physicalmodel is createdin two steps. The userhasto assigneachprimitive a material. TheSCARAB model modulethen computesfor eachprimitive and eachcompoundthe massproperties,usingthe geometricdimensionsandthe materialdensity. The densityandall otherpropertiesneededfor the re-entryanalysishave to be storedin the SCARAB materialdatabase.Thereforethe requiredpropertiesof thematerialsusedfor modellingtheATV componentshadto beprovidedin advance.

2.2 The geometricand physical modelof ATV

Thetoplevel compoundof thegeometricATV modelis thecompleteATV geometry. This compoundiscomposedof thelower-level compoundsshown in Table1. WhennamingtheSCARAB compoundstheofficial ATV abbreviationshave beenused.

Figure3 shows a view of thepanellisedexternalsurfaceof thecompletegeometricATV model. Com-ponentswhichcanberecognizedin thisfigurearetheMDPS,thesolararrays,variousthrusters,andtheRDS.

In thefollowing themodellingof thefirst sublevel of thecompoundsof Table1 areshortlyoutlined.


SCARABcompoundname Partof ATV Main partof ATVEPB EquippedPropulsionBay SCSpacecraftSubassemblyEAB EquippedAvionicsBaySOL-Gen SolarGeneratorsEEB EquippedExternalBay ICC IntegratedCargo CarrierEPM EquippedPressurisedModuleMDPS MeteoroidDebrisProtectionSystem MPDS

Table1: Thesublevel 1 compoundscomposingtheATV

2.2.1 The Equipped PropulsionBay, EPB

TheEPBis modelledfrom following components:

SCARABcompoundname Partof ATVSDM SeparationdistancingmoduleTKM Tankagemodulewith propulsiontanksTHM ThrustermoduleM thrustblock Main thrusterblockAC4 ClusterEPB 4 blocksof attitudecontrolthrustersFDV-PM-Mon Feedanddrainvalve for MON tankFDV-PM-He Feedanddrainvalve for Helium tankFDV-PM-MMH Feedanddrainvalve for MMH tankFDV-PM-He Feedanddrainvalve for He tank

Table2: Thetoplevel componentsof theEPB

Figure4 shows the modelledEPB with a view to the interior. Visible are the main thrusters(THM),the attitudecontrol thrusters(AC4), andsomepropellanttanks(TKM). Detaileddataon the modelledgeometryandthe masspropertiesof the EPB aredocumentedin [6]. The contentof the tanksin theTKM hasbeenmodelledassphericalshellattachedto theinnersurfaceof thetanks.Shellthicknessandfuel volumeis adjustedto obtain,consideringthefuel density, therequestedfuel massin thetanks.

2.2.2 The Equipped AvionicsBay, EAB

TheEAB is modelledfrom following components:

SCARABcompoundname Partof EABAVM AvionicsModulestructureAV-Equip-ring Avionicsequipment

Table3: Thetoplevel componentsof theEAB

TheAvionicsModulestructureis composedof alowerandupperring andtheconicalshell.TheAvionicsequipmentcontainsbatteries,gyrosandharness.


2.2.3 The Solar Generators,SOL-Gen

TheSolarGeneratorsconsistof four identicalsolarpanelarrayswith deployableextensionarms. Thecorrespondingcompoundsare namedSP-array. Eachis composedfrom four rectangularpanels(cf.Fig. 2), hingesanda rod.

2.2.4 The Equipped External Bay, EEB

TheEquippedExternalBayis thefirst partof theICC. It housestheRefuellingSystemRFS,3 GasTanksand3 WaterTanks.ThemodelledEEBconsistsof thefollowing sublevel compounds:

SCARABcompoundname Partof EEBEM Externalmodulestructure

EM-WEB-ASSReinforcementwebstructure.EM-Equip WTA Watertankswith content

GTA Gastankswith contentRFSRefuellingsystemwith contentFDV Fill anddrainvalves

EM-piping Piping

Table4: Thecomponentsof theEEB

Figure5 showsaview from thetopto theEEB.Onecanrecognizethetanksandthereinforcementwebslocatedbetweenthetanks.

2.2.5 The Equipped PressurisedModule, EPM

TheEquippedPressurisedModule is thesecondpartof the ICC. It houses4 rack rows consistingof atotal of 8 doubleracks.Eachdoublerackcontainsequipmentcontainerswith cargo. In themodelthereis onecontainerin eachsubrack.

ThemodelledEPBconsistsof thefollowing subcompounds:

SCARABcompoundname Partof EPBPM Pressurisedmodule.IncludestheRussianDockingSystemRDSRacks 4 rackrows with containersandcargoDummy-1-PM Dummymass1Dummy-2-PM Dummymass2Dummy-SUP-PM Dummyandsupportfor racksAC-4Cluster-PM 4 blocksof attitudecontrolthrusters

Table5: Thecomponentsof theEPM

Figure6 shows theexternalgeometryof theEPM.Figure7 showsaview to theinteriorof theEPMafterremoving thefront partof theEPM walls.

The waffle supportstructureof the externalwalls wasnot modelled. All pressurewalls aremodelledwith constantthicknessof 9 mm (cylindrical chamber)and10 mm for cones.Themodelledequipmentconsistsof rackrows with content.Eachof the 8 original ATV Racksis modelledby 2 rack elements.


Thusa rack row in themodelconsistsof 4 racks. Dry cargo of the racksis modelledby a simpleboxcentredin eachrack. 4 clustersof ACScontrol thrustersaremountedat thefront endof thecylindricalpressurechamber.

2.2.6 The Meteoroid and Debris ProtectionSystem,MDPS

The ATV-MDPSis composedof four protectionsubsystems.EachMDPS subsystemconsistsof a setof thin cylindrical or conicalshells. The radial distancebetweeneachMDPS shell andthe protectedstructureis 65 mm. To connectthe MDPS with the main structurecylindrical rings at eachendof aMDPSmodulewhereused.

SCARABcompoundname Coveredpartof ATV Thickness[mm] (Material: AA6061)MDPS-PB Propulsionbay 0.8MDPS-EAB Avionicsbay 2.0MDPS-EM Externalmodule 1.2MDPS-PM Pressurisedmodule 1.2

Table6: Thesubsystemsof theMDPS

2.3 Massbudgets

Themasspropertiesof thephysicalATV modelhave to matchtheofficial massbudgetasspecifiedinthe correspondingreferencedocuments(see[6] for details). Due to their differencesin the cargo themassbudgetof thenominalandnon-nominalcasediffer. Table7 shows thetotal values.Thedifferencesbetweenmodelledandreferencevaluesarewithin thesystemmargin of 7%.

ATV component Referencemass[kg] SCARAB modelmass[kg] Error [kg] Error [%]Nominalcase

SC 5434 5119 -315 -5.9ICC 11075 11050 -25 -0.3ATV nominal 16509 16169 -340 -2.165

Non-nominalcaseSC 10053 9713 -340 -3.4ICC 8605 8542 -63 -0.7ATV non-nominal 18658 18255 -403 -2.16

Table7: Comparisonbetweenreferenceandmodelmassesfor theATV andits subcomponentsSCandICC

The non-nominalATV hasabout2 tons(2000kg) moremass.A comparisonon subcomponentlevelshows thatin additionthemassdistribution in bothcasesis quitedifferent.Thenon-nominalSCis about4.5t heavier thanthenominalSC,while thenon-nominalICC is 2.5t lighter thanthenominalICC. Thisis dueto thedifferencein theamountanddistribution of thecargo:

Table9 summarizesthemasspropertiesof both modelledconfigurations.The differencesin the masspropertieshave asignificantinfluenceon theflight dynamicbehaviour duringre-entry.


Cargo type Massnominal[kg] Massnon-nominal[kg]EPB(SC)

MON 84 2944MMH 50 1784He 6 26subtotal 140 4754

EEB (ICC)NTO 8 554UDMH 4 306He 0 3N2 0.3 99H2O 840 840subtotal 852.3 1802

EPM(ICC)Dry cargo 5000 1568Total 5992.3 8124

Table8: Cargo distribution in thenominalandnon-nominalATV

Quantity ATV nominal ATV non-nominalTotalmass[kg] 16169 18255Centerof mass,�� [m] 4.087 3.000Momentof inertia,

��[kg m ] 46291 50509

Momentof inertia,��

[kg m ] 86500 107261Momentof inertia,

� � [kg m ] 89647 109363

Table9: Modelledmasspropertiesfor thenominalandnon-nominalATV


Figure1: ATV maincomponents


Figure2: ATV with deployedsolararraysandmaincoordinatesystem

Figure3: Frontview of thecompleteexternalgeometricATV model

Re-entryAnalysisfor theATV with SCARAB Draft Final ReportIssue2 11

Figure4: View of thegeometricmodelof theEPB,with aview to inside

Figure5: View of thegeometricmodelof theEEB


Figure6: View of theexternalgeometricmodelof theEPM

Figure7: View to partof theinternalgeometricmodelof theEPM


3 Re-entry Analysis

3.1 Intr oduction

The re-entryhistory wascomputedfor both configurations:ATV nominalandATV non-nominal. Acomputationjob startswith thespecificationof the initial conditionsfor the trajectoryandattitudemo-tion, thedefinitionof someparametersof thenumericalintegrator, andgiving thesurfacetemperature.Theinitial conditionswerethesamefor thenominalandthenon-nominalcase.

Startingfrom theinitial conditions,thestatevectorof thespace-vehicleis propagatedby numericalinte-grationuntil a disintegration(fragmentation)eventoccurs.Thedisintegrationcanbeeithermechanicalor thermal.In themechanicalcase,thestructuralstressin oneof thepredefinedjointsexceedsthebreak-ing stressandthespace-vehiclemodelhasto besubdivided into theresultingfragments.In thethermalcase,somepart loosesits contactto the remainingparts,if all connectingsurfacepanelsaredestroyedby melting. In casethattheintegrity of thespace-vehicleremainsintact,meltingof singlesurfacepanelsdoesnot result in a programinterrupt. Thereforethe total massof thespace-vehicle(or fragment)candecreasecontinuouslyduringcalculation,whereasafterfragmentationthemassundergoesa jump.

In thefollowing there-entryhistoriesarepresentedin somedetailfor theearlyre-entryphase,startingattheinital conditionsandterminatingwith thefirst disintegrationevent,whichin bothconfigurationsis thebreakingof thesolararrays.This resultsin thegenerationof fivefragments:thefour solararraysandthemainbody. After thisfirst fragmentationthemainbodywasfolloweduntil thenext (2nd)disintegration,generatingagainone large main fragmentand several smaller fragments. The largest fragmentwasfollowedthroughall subsequentdisintegrationsuntil groundimpact.Thesequencenumberof themaindisintegrationeventswasusedfor numberingthefragmentationevents.Thefragmentgenerationhistorywill besummarized.For themainfragmentthecompletere-entryhistorywill besummarizedat theendof thesectionfor eachconfiguration.A detailedlist of all fragmentsgeneratedduringthewholere-entryhistoryis givenchapter5.

3.2 The Initial Conditions

Theinitial conditionsfor thespace-vehiclestatevectorbeforere-entrywerespecifiedasorbitalelementsby theATV team.They are:

Semi-majoraxis: � = 6553.137kmEccentricity: � = 0.026705Inclination: � = 51.6�Longitudeof ascendingnode: � = -30�Argumentof perigee: � = 310�Trueanomaly: � = -98.543�

Theseparameterscorrespondto aninitial altitudeof �� km.

The attitudeof ATV was assumedto be head-on,which meansthat all Euler anglesof the rotationbetweenbody-fixedandorbit-definedcoordinateframesweresetto zeroinitially. Theangularvelocitywassetto a 10�� s rotationaboutthepitchaxis(body-fixedy-axis).

Theinitial surfacetemperaturewassetconstantto 300K for thewholesurface.


3.3 Re-entry Analysis for the Nominal Case

3.3.1 Trajectory and attitude motion up to the first destruction event

Figure8 shows the flight altitudeof the ATV during the early re-entryphase.The altitudedecreasesalmostlinearly with time. Figure9 shows the flight (aerodynamic)velocity of the ATV. The velocityincreasesinitially, which meansthat the altitudedecreaseis dueto the initial orbital parameters,not adrageffect. After about570s thevelocity startto level off. This correspondsto analtitudeof about90km, whereaerodynamicdragis expectedto becomeimportant.

The atmosphericinfluenceon the aerodynamicscanbe seenin Figure10. It shows the linear andan-gularaccelerationsactingon theATV by aerodynamicforceandtorque.Theaerodynamicinfluenceisproportionalto theatmosphericdensity. In addition,theaerodynamicdragis modulatedby a periodof18 s. Thisagreesnicelywith theinitial angularvelocity of 10� /s= 1 rev/36 s,sincetheprojectedareaisthesametwice a revolution.

In the chosenspace-vehiclemodelthe only partswhich canbe destroyed by mechanicalloadsarethesolararrays.Figure11 shows theactualandthebreakingstressin two of thejoints asfunctionof flighttime. At highaltitudes,wheretheatmosphericdensityis small,themechanicalloadsarealsosmall.Onlyanalmostconstantcontribution from inertial loadsarepresentthere.For loweraltitudestheaerodynamicmomentsbecomeimportant.Theloadsareoscillatingaccordingto therotationalmotion.They increaseproportionalto the increasein atmosphericdensitywith decreasingaltitude. At analtitudeof about92km, themechanicalloadscrossthebreakingstresscurve. Thebreakingstresslowerswith time becausethe joints areheatedby thefreestream,andthebreakingstressdecreaseswith temperature.Wheretheactualstressreachesthebreakingstress,thejointsbetweensolararraysandthespace-vehiclebodybreak.

Figure12 shows thehistoryof themaximumtemperatureon thespace-vehicle. It startsto riseafter300s flight time,correspondingto analtitudeof 160km, andcorrespondingto a maximumheatflux of 500W/m . Theheatflux history is shown in Figure13. After 530s flight time ( � �"!�� km, #��%$ � �'&��kW/m ) themaximumtemperaturereachesaconstantvalueof 870K. This is themeltingtemperatureofthesolararrays,which aremadefrom Aluminium. In fact,beforethesolararraysbreakaway, they startmelting,but at thetime of breaking,themeltedmassfractionis small.

3.3.2 Fragmentation history

1st fragmentation

The breakingof the solararraysis the first disintegration event detected.It occursafter 576 secondssimulatedflight time. Theflight altitudeis 92 km at thattime. Therearefive fragmentsgenerated:1: themainbody(trunk),2–5: four solararrays.

A pictureandsomecharacteristicdataof these(andall following) fragmentsarelisted in chapter5.2.For example,Figure57 shows thegeometryof themain fragmentwhich is thecompleteATV withoutthesolararrays.Oneof thebrokensolararraysis shown in Figure58.

Thehistoryof oneof thesolararrayswascomputed.After 583s total flight time, at 90.8km altitude,it disintegratesinto threesmallersegments2.1–2.3. The first segmentwas tracked further. It finallydemisesafter 663 s, at 77.1 km altitude. It wasconcluded,that all solararrayswill melt completely


80000

100000

120000

140000

160000

180000

200000

0 100 200 300 400 500 600

Alti

tude

[m](

Time [s]

Figure8: Altitude of thenominalATV duringtheearlyflight phase

7480

7500

7520

7540

7560

7580

7600

7620

0 100 200 300 400 500 600

Vel

ocity

[m/s

]

Time [s]

Figure9: Velocityof thenominalATV duringtheearlyflight phase

1e-07

1e-06

1e-05

0.0001

0.001

0.01

0.1

1

0 100 200 300 400 500 600

Line

ar a

ccel

erat

ion

[m/s

**2]

)

Ang

ular

acc

eler

atio

n [1

/s**

2]

*

Time [s]

linearangular

Figure10: Aerodynamicaccelerationactingon thenominalATV duringtheearlyflight phase


100000

1e+06

1e+07

1e+08

1e+09

1e+10

0 100 200 300 400 500 600

Str

ess

[N/m

**2]

Time [s]

Act. stress (2)Max. stress (2)Act. stress (4)

Max. stress (4)

Figure11: Actualandbreakingstressin two of thejointsconnectingthesolararraysto thespace-vehicleduringtheearlyflight phase

300

400

500

600

700

800

900

0 100 200 300 400 500 600

Tem

pera

ture

[K]

+

Time [s]

Figure12: Max. temperatureon thenominalATV duringtheearlyflight phase

10

100

1000

10000

100000

0 100 200 300 400 500 600

Hea

t flu

x [W

/m**

2]

Time [s]

Figure13: Max. heatflux to thenominalATV duringtheearlyflight phase


duringre-entry.

2nd fragmentation

After 675 s total flight time, at 75 km altitude,thenext fragmentationis detected.Four fragmentsaregenerated:1.1: theremainingmainbody,1.2: thetopwall of theEquippedPressurisedModule(EPM),1.3: theRussianDockingSystem(RDS),1.4: a fragmentof theMeteoroidandDebrisProtectionShield(MDPS).

Thehistoryof fragments1.2–1.4wasinvestigated.Fragments1.2and1.3survive thesimulatedre-entry.Fragment1.4demisesafter677.7s total flight time,at74.8km altitude.

3rd fragmentation

After 740 s total flight time, at 64 km altitude, the front disk in the EPM (fragment1.1.2) loosesitscontactto themainbody. Fragment1.1.2wastracked. It survivesthere-entry.

4th fragmentation

After 792s total flight time,at52.5km altitude,13 fragmentsaregenerated:1.1.1.1:theremainingmainbody,1.1.1.2: the thrusterblock of theEquippedPropulsionBay (EPB), including the four Attitude Controlthrusters(ACS)locatedcircumferentially,1.1.1.3:four fuel tanksmountedon a ring,1.1.1.4–9:six Fill andDrain Valves(FDV),1.1.1.10–11:two AttitudeControlthrusters(ACS)from theEPM,1.1.1.12–13:two cargo rackrows from theEPM.

Sincethe thrustersareconnectedto the fuel tanksby feedlines, andthe tanksareseparatedfrom thethrustersby thisdisinegrationevent,its is assumedthatthefuel flowsoutof thetanks.Thereforethefuelis removedfrom thespace-vehiclemodelbeforecontinuingthere-entrycalculation.

Fragment1.1.1.2wastracked. It breaksafter793s total flight time into 2 fragments:1.1.1.2.1:a ring-shapedwall fragmentwith thefour ACSattached,1.1.1.2.2:theEPBthrusterblock.Thethrusterblockdisintegratesafter816s/at47.2km into 4 separatethrusters.Thethrusterssurvive there-entry. For fragment1.1.1.3seetheanalogouscasein thenon-nominalre-entry(1.1.1.11).Fragment1.1.1.4was tracked. It survives the re-entry. Fragment1.1.1.11was tracked. It melts partially, thendisintegratesinto 2 nozzlesat 815s/ 47.7km. They survive there-entry. Thecargo racks(1.1.1.12+13)weretrackedin thenon-nominalcase(1.1.1.1.5).

5th fragmentation

After 803.5s total flight time,at 49.4km altitude,5 fragmentsaregenerated:1.1.1.1.1:theremainingmainbody,1.1.1.1.2:a tankfrom theEquippedExternalBay (EEB),1.1.1.1.3:oneAttitudeControlthruster(ACS)from theEPM,1.1.1.1.4–5:thelasttwo cargo rackrows from theEPM.

Fragment1.1.1.1.2wastracked. It survivesthere-entry.


3.3.3 Summary of the fragmentation history for the nominal case

Table10 summarizesthe fragmentationeventsdetectedduring re-entryanalysisof the nominalATV.Table11 lists the secondaryfragmentsgeneratedduring trackingof the primary fragments.Time andaltitudearethetotal simulationtime andtheflight altitudeat which thefragmentsweregenerated.Theletters in the fate column mean: F = Fragmentation,D = Demise(completemelting), S = Survival(includescaseswith somemasslossby melting).

Event# Fragment# FragmentName Time[s] Alt.[km] Fate1 1 Main 576 92 F

2–5 4 solararrays F2 1.1 Main 675 75.2 F

1.2 EPM.PMtop S1.3 RDS S1.4 MDPSwall fragment D

3 1.1.1 Main 740 63.8 F1.1.2 EPM disk S

4 1.1.1.1 Main 792 52.5 F1.1.1.2 EPBthrustblock F1.1.1.3 ConnectedEPBfuel tanks F1.1.1.4–9 6 FDV S1.1.1.10–11 2 EPM ACS F1.1.1.12–13 2 EPM rackrows S

5 1.1.1.1.1 Main 803.5 49.4 F1.1.1.1.2 EEB tank S1.1.1.1.3 EPM ACS S1.1.1.1.4–5 2 EPM rackrows S

6 1.1.1.1.1.1 Main 812 47 F1.1.1.1.1.2 EEB tankpair S1.1.1.1.1.3 EPM ACS S

7 1.1.1.1.1.1.1 Main 854 35.9 S1.1.1.1.1.1.2–3 2 solararrayhinges S1.1.1.1.1.1.4 EPM wall fragment S

Table10: List of mainfragmentsgeneratedin thenominalATV re-entrycaseMain event# Fragment# FragmentName Time[s] Alt.[km] Fate1 2.1 Solararraysegment 583 90.8 D4 1.1.1.2.1 EPBbacksidering 793 52.3 F

1.1.1.2.2 EPBthrustblock F1.1.1.2.2.1 Thruster 816 47.2 S1.1.1.10.1 EPMACSnozzle 815 47.7 S

Table11: List of sub-fragmentsgeneratedin thenominalATV re-entrycase


3.3.4 Summary of the re-entry history for the main body fragment

Figure 18 shows the flight altitude as function of time for the ATV (in the beginning) and the mainfragment(aftereachfragmentation).Figure19 shows thecorrespondingvelocities.

Figure20resolvesthere-entrygroundtrackinto thepartialtracksof themainfragment.Figure21showsthemasshistoryfor themainfragment.

Figure 22 shows the aerodynamicangleof attackduring re-entry. The initial rotation changesto astabilisedoscillationafterthefirst fragmentation.Thestability getslostaftertheforth fragmentation.

Figure23shows theaerodynamicdecelerationfor themainfragmentduringre-entry. Unlike thealtitudeandvelocity, theaerodynamicforceshows rapid oscillationsin its time history. This is dueto the fastangularmotion. Sincethevelocity is a resultof a time integrationof theacceleration,theoscillationsintheaccelerationappearto besmearedout in thevelocity. A maximumof themeandecelerationappearsat t=820 s, with a value of 80 m/s . This value is nearthe value of 8g, which is to be expectedasmaximumfor ashallow initial flight pathangle.

Figure24 shows the aerodynamicheatflux to the main fragmentduring re-entry. It alsoshows somehigh-frequentoscillations.Thereappearsa maximumof about800kW/m at t=790s.As expected,themaximumof theheatflux is reachedearlierthanthemaximumof theaerodynamicdeceleration.

0

20000

40000

60000

80000

100000

120000

500 600 700 800 900 1000 1100

Alti

tude

[m](

Time [s]

ATV nominalafter 1. frag.after 2. frag.after 3. frag.after 4. frag.after 5. frag.after 6. frag.after 7. frag.final descent

Figure18: Altitude of thenominalmainATV bodyfragmentduringthewholere-entryflight


0

1000

2000

3000

4000

5000

6000

7000

8000

500 600 700 800 900 1000 1100

Vel

ocity

[m/s

]

Time [s]


Figure19: Velocityof thenominalmainATV bodyfragmentduringthewholere-entryflight

-54

-53

-52

-51

-50

-49

-48

-47

-46

-160 -155 -150 -145 -140 -135 -130 -125 -120

Latit

ude

[deg

]

*

Longitude [deg]


Figure20: Groundtrackof thenominalmainATV bodyfragmentduringthewholere-entryflight

0

5000

10000

15000

20000

500 600 700 800 900 1000 1100

Mas

s [k

g],

Time [s]

ATV nominalafter 1. frag.after 2. frag.after 3. frag.after 4. frag.after 5. frag.after 6. frag.after 7. frag.

Figure21: Massof thenominalmainATV bodyfragmentduringthewholere-entryflight


-150

-100

-50

0

50

100

150

500 600 700 800 900 1000 1100

Ang

le o

f Atta

ck [

deg]

-

Time [s]


Figure22: Aerodynamicangleof attackof thenominalATV duringre-entry

0

20

40

60

80

100

120

500 600 700 800 900 1000 1100

Aer

odyn

amic

dec

eler

atio

n [m

/s**

2]

.

Time [s]


Figure23: Aerodynamicaccelerationactingon thenominalATV duringthewholere-entryflight

0

100000

200000

300000

400000

500000

600000

700000

800000

900000

1e+06

500 600 700 800 900 1000 1100

Hea

t flu

x [W

/m**

2]

Time [s]


Figure24: Max. heatflux to thenominalATV duringthewholere-entryflight


3.4 Re-entry Analysis for the Non-Nominal Case

3.4.1 Trajectory and attitude motion up to the first destruction event

In the non-nominalcase,the massandmomentsof inertia arehigherthanin the nominalcase.In theearlyentryphasethishaslittle influenceon thetrajectory. Themechanicalloadson thesolararrayjointsaresimilar to thenominalcase.They dependonly on theangularmotion,noton themassproperties.

100000

1e+06

1e+07

1e+08

1e+09

1e+10

0 100 200 300 400 500 600

Str

ess

[N/m

**2]

Time [s]

Act. stress (2)Max. stress (2)Act. stress (4)

Max. stress (4)

Figure25: Actualandbreakingstressin two of thejointsconnectingthesolararraysto thespace-vehicleduringtheearlyflight phase

3.4.2 Fragmentation history

1st fragmentation

After 567s, at 93.5km altitude,thesolararraysbreak.Thegeometryof the fragmentsis thesamelikein thenominalcase(seeFigures86 and87). Thereforethesolararraysareassumedto melt completelyalsoin thenon-nominalcase.

2nd fragmentation

After 675stotalflight time,at75.4km altitude,theRussianDockingSystem(RDS)with thetopwall oftheEquippedPressurisedModule(EPM)attachedloosesits contactto theremainingmainbody.

Fragment1.2wastracked. It disintegratesinto 2 partsafter720s total flight time,at67.4km altitude:1.2.1:theEPM topwall,1.2.2:theRDS.Both fragmentsweretracked.They survive there-entry.

3rd fragmentation

After 690 s total flight time, at 72.9 km altitude, the thrusterblock of the EquippedPropulsionBay(EPB) loosesits contactto the main body. Sincethe thrustersareconnectedto the fuel tanksby feedlines, which areassumedto be torn apartduring this disinegration event, its is assumedthat the fuel


flowsoutof thetanks.Thereforethefuel is removedfrom thespace-vehiclemodelbeforecontinuingthere-entrycalculation.

The thrusterblock wastracked. It disintegratesinto 4 thrustersafter 694 s total flight time, at 72.2 saltitude.Onethrusterwastracked. It survivesthere-entry, henceall thrusterwill survive.

4th fragmentation

After 798s total flight time,at53.1km altitude,17 fragmentsaregenerated:1.1.1.1:theremainingmainbody,1.1.1.2:awall fragmentof theEPBwith two Attitude ControlThrustersstill attached,1.1.1.3–4:theothertwo ACS,whichhave lost their contactto theEPBwall,1.1.1.5–8:four fuel tanks1.1.1.9–10:two Helium tanks,1.1.1.11:theremainingfour fuel tanks,still attachedto aconnectingring,1.1.1.12–15:four Fill andDrainValves(FDV)1.1.1.16:oneoutof four ACSlocatedon thefront of theEPM,1.1.1.17:adisk locatedin theEPM.

Fragment1.1.1.2wastracked. It disintegratesinto 4 fragmentsafter803s total simulationtime,at 51.9saltitude:1.1.1.2.1–2:two wall fragments,1.1.1.2.3–4:two EPBACS(cf. 1.1.1.3).

Fragment1.1.1.3,5, 9, 12,and16 weretracked.All survive there-entry.

Fragment1.1.1.11wastracked. The connectingring disintegratesinto 2 fragmentswith 2 tankseachafter800s/ at 52.6km altitude. Oneof this fragmentswastracked. It disintegratesafter805s/ at 51.4km. Thereleasedtankssurvive there-entry.

Fragment1.1.1.17correspondsto fragment1.1.2in thenominalcase,which survivesthe re-entryevenwhile releasedat higheraltitude.

5th fragmentation

After 824s total flight time,at46 km altitude,9 fragmentsaregenerated:1.1.1.1.1:theremainingmainbody,1.1.1.1.2–4:theremainingthreeACSlocatedon thefront of theEPM,1.1.1.1.5–8:all four rackrows locatedinsidetheEPM,1.1.1.1.9:a largefragmentof theEPMwall.

TheEPM ACScorespondto fragment1.1.1.16,whichsurvivesthere-entry.

Fragments1.1.1.1.5and1.1.1.1.9weretracked.They survive re-entry. It hasto benoted,thatthesecondfragmentloosesabout20%of its masson its waydown.

The final main fragmentis shown in Figure105. After 880 s total flight time, at 27.7km altitudeandMachnumber3.8,thetrajectorycomputationfor this fragmentis stopped.Thefinal descentis computedwith a 3D propagator.

Ground dispersion

Figure26showsthefinal partof thegroundtrackfor severalfragmentsgeneratedduringthenon-nominal


re-entry. Angleof attackandbankanglewerevariedin stepsof 30degrees.Figure27shows thegroundtracksassuminga tumbling motion. Figure 28 and29 show the final altitudesandvelocitiesfor thefragmentsfor theballisticcase.

-52.2

-52

-51.8

-51.6

-51.4

-51.2

-51

-50.8

-136 -134 -132 -130 -128 -126 -124 -122 -120

Latit

ude

[deg

]

Longitude [deg]

1.1.1.1.11.1.1.1.11.1.1.1.1

1.1.1.11.1.11.2.11.2.11.2.21.2.2

1.1.2.11.1.1.31.1.1.51.1.1.9

1.1.1.161.1.1.1.5

Figure26: Grounddispersionfor variableangleof attack/bankangle

-52.2

-52

-51.8

-51.6

-51.4

-51.2

-51

-50.8

-136 -134 -132 -130 -128 -126 -124 -122 -120

Latit

ude

[deg

]

Longitude [deg]

1.1.1.1.11.1.1.1.11.1.1.1.1

1.1.1.11.1.11.2.11.2.11.2.21.2.2

1.1.2.11.1.1.31.1.1.51.1.1.9

1.1.1.161.1.1.1.5

Figure27: Grounddispersionfor tumblingmotion


0

10000

20000

30000

40000

50000

60000

70000

-136 -134 -132 -130 -128 -126 -124 -122 -120 -118

Alti

tude

[m](

Longitude [deg]

1.1.1.1.11.1.1.1.11.1.1.1.1

1.1.1.11.1.11.2.11.2.11.2.21.2.2

1.1.2.11.1.2.11.1.1.31.1.1.51.1.1.9

1.1.1.161.1.1.1.5

Figure28: Fragmentaltitudesvs. longitude.Final descenttumbling

0

1000

2000

3000

4000

5000

6000

7000

8000

-138 -136 -134 -132 -130 -128 -126 -124 -122 -120 -118 -116

Vel

ocity

[m/s

]

-

Longitude [deg]

1.1.1.1.11.1.1.1.11.1.1.1.1

1.1.1.11.1.1

1.21.2.11.2.11.2.21.2.2

1.1.2.11.1.2.11.1.1.31.1.1.31.1.1.51.1.1.51.1.1.91.1.1.9

1.1.1.161.1.1.161.1.1.1.51.1.1.1.5

Figure29: Fragmentvelocitiesvs. longitude.Final descenttumbling


3.4.3 Summary of the fragmentation history for the non-nominal case

Table12summarizesthefragmentationeventsdetectedduringre-entryanalysisof thenon-nominalATV.

Event# Fragment# Fragmentname Time[s] Alt.[km] Fate1 1 Main 567 93.5 F

2–5 4 solararrays D2 1.1 Main 675 75.4 F

1.2 RDS+EPM.PMtop F3 1.1.1 Main 690 72.9 F

1.1.2 EPBthrustblock F4 1.1.1.1 Main 798 53.1 F

1.1.1.2 EPBbacksidering F1.1.1.3–4 2 EPBACS S1.1.1.5–8 4 EPBfuel tank S1.1.1.9–10 2 Heliumtanks S1.1.1.11 Fourconnectedfuel tanks F1.1.1.12–15 4 FDV S1.1.1.16 EPMACS S1.1.1.17 Disk S

5 1.1.1.1.1 Main 824 46 S1.1.1.1.2–4 ACSfront S1.1.1.1.5–8 Rackrow S1.1.1.1.9 EPMwall fragment S

Table12: List of fragmentsgeneratedwhile tracingthemainbodyfragment

Main event# Fragment# FragmentName Time[s] Alt.[km] Fate2 1.2.1 EPM.PMtop 720 67.4 S

1.2.2 RDS S3 1.1.2.1 Thruster 694 72.2 S4 1.1.1.2.1-2 Wall fragments 803 51.9 D

1.1.1.2.3-4 2 EPBACS S1.1.1.11.1 Two connectedtanks 800 52.6 F1.1.1.11.1.1 Tank 805 51.4 S

Table13: List of fragmentsgeneratedwhile tracingsub-fragments.


3.4.4 Summary of the re-entry history for the main body fragment

Figure 30 shows the flight altitude as function of time for the ATV (in the beginning) and the mainfragment(aftereachfragmentation).Figure31 shows thecorrespondingvelocities.

Figure32resolvesthere-entrygroundtrackinto thepartialtracksof themainfragment.Figure33showsthemasshistoryfor themainfragment.

Figure 34 shows the aerodynamicangleof attackduring re-entry. The initial rotation changesto astabilisedoscillationabout180 deg, with theEPB facingthe free stream,after the first fragmentation.Thestability getslostaftertheassumedlossof thepropellantin thethird fragmentation.

Figure35 shows theaerodynamicdecelerationfor the main fragmentduring re-entry. In the region ofthemaximumthedecelerationshows strongrapidoscillationsin its time history.

Figure36 shows the aerodynamicheatflux to the main fragmentduring re-entry. It alsoshows somehigh-frequentoscillations.Thereappearsamaximumof about700kW/m at t=790s.

0

20000

40000

60000

80000

100000

120000

500 600 700 800 900 1000 1100

Alti

tude

[m](

Time [s]

ATV non-nom.after 1. frag.after 2. frag.after 3. frag.after 4. frag.after 5. frag.final descent

Figure30: Altitude of thenon-nominalmainATV bodyfragmentduringthewholere-entryflight


0

1000

2000

3000

4000

5000

6000

7000

8000

500 600 700 800 900 1000 1100

Vel

ocity

[m/s

]

Time [s]


Figure31: Velocityof thenon-nominalmainATV bodyfragmentduringthewholere-entryflight

-54

-53

-52

-51

-50

-49

-48

-47

-46

-160 -155 -150 -145 -140 -135 -130 -125 -120

Latit

ude

[deg

]

*

Longitude [deg]


Figure32: Groundtrackof thenon-nominalmainATV bodyfragmentduringthewholere-entryflight

0

5000

10000

15000

20000

500 600 700 800 900 1000 1100

Mas

s [k

g],

Time [s]

ATV non-nom.after 1. frag.after 2. frag.after 3. frag.after 4. frag.after 5. frag.

Figure33: Massof thenon-nominalmainATV bodyfragmentduringthewholere-entryflight


-150

-100

-50

0

50

100

150

500 600 700 800 900 1000 1100

Ang

le o

f Atta

ck [d

eg]

-

Time [s]


Figure34: Aerodynamicangleof attackof thenominalATV duringre-entry

0

10

20

30

40

50

60

70

80

90

100

110

120

500 600 700 800 900 1000 1100

Aer

odyn

amic

dec

eler

atio

n [m

/s**

2]

.

Time [s]


Figure35: Aerodynamicaccelerationactingon thenon-nominalATV duringthewholere-entryflight

0

100000

200000

300000

400000

500000

600000

700000

800000

900000

1e+06

500 600 700 800 900 1000 1100

Hea

t flu

x [W

/m**

2]

Time [s]


Figure36: Max. heatflux to thenon-nominalATV duringthewholere-entryflight


4 Fluids and Tanks

4.1 Tank modelling

The resultsfor tank bursting shown in this chapterare generatedby a standalonetool not yet fullyintegratedin the SCARAB system(but part of the SCARAB ExtensionToolbox). This tool readsthetemperaturehistoryfilescalculatedwith SCARABanddeterminestankandburstpressurefor eachtimestep.Theburstpressureis computedfrom themaximumshell temperatureof thetank,thetankpressureis computedfrom the meantemperatureof the tank contents. This tank bursting analysisis shownschematicallyin Figure37.

/1032547698:6<;=0?>:@BADCFEHG7G;IEH6KJ3E?LM0FNO8:LPE QSRUT?V1W=T?V:XZY\[?V^]PRHV^]WIRH_9`3RHabTF]Oc:aPR

dfehgjikgml

npo:qbr�sutvqbwUr^rFo5qbw x=y?z:{1|p}P~U�^�F�:}P~

�9� ��K��

��S�3�� 9�

Figure37: Schematicdescriptionof thetankburstinganalysis

If the tankpressureexceedstheburstpressure,a tankburstingeventoccurs.Thedestructive effectsofsuchaneventarenotmodelledin SCARAB.Thetanksarejustdepleted.

To modeltanksa detaileddescriptionof the tank (e.g. volume,nominalburstpressure)andits fillings(e.g. massof liquid andgaseouscontents)is needed.Thecorrespondingdataarespecifiedin separateinputfileswhicharereadby thetanktool. Theinitial tankconditionsfor eachtankof theATV areshownin Table14 for nominalre-entryandin Table15 for non-nominalre-entry. Thesetwo tableshow thatthereare9 differentcasesor tanktypesfor eachre-entryconfiguration.

Looking at the ATV modeldescriptionfor SCARAB it canbe seenthat for this modelsomesimplifi-cationsaccordingto the tankshave beenmade.First thepressuregasof tankswith liquid contentshasnever beenmodelledbecauseof its low mass.To calculatethe tankpressurea uniform temperatureofall tankcontentsis assumed.Thismeansthatalsothepressuregasin atankhasthemeantemperatureoftheliquid.

Seconda filling materialnamedEMPTY hasbeenintroducedto modellemptytanks.Neverthelessthetanksmodelledasemptyarenot reallyempty. Therearesmallamountsof liquidsandgasesin them.ThematerialEMPTY hasa very low thermalconductivity andthereforekeepstheinitial temperatureduring


No. Tank Contents Initial condition�U� �H�� Material liquid gaseous

�:� [ ¡K¢ ] [bar] [kg] [kg] [bar] [K]

1 1.694 45 TiAl6V4 42(MON-3) 4.807(He) 182 1.694 45 TiAl6V4 25 (MMH) 4.810(He) 183 0.400 820 CFK - 3.851(He) 604 0.215 45 AlCu6Mn 4 (NTO) 0.034(He) 15 0.215 45 AlCu6Mn 2 (UDMH) 0.034(He) 1 3006 0.020 800 TiAl6V4 - £ 1 g (He) 0.17 0.130 576 CFK - 0.167( ¤ ) 18 0.130 576 CFK - 0.146( ¥ ) 19 0.301 88 CFK 280( ¦ ¤ ) 0.022( ¥ ) 1

Table14: NominalRe-entryConfiguration

No. Tank Contents Initial Condition�F� �?�§� �Material liquid gaseous

�:� [ ¡K¢ ] [bar] [kg] [kg] [bar] [K]

10 1.694 45 TiAl6V4 1472(MON-3) 1.888(He) 1811 1.694 45 TiAl6V4 892(MMH) 1.919(He) 1812 0.400 820 CFK - 17.972(He) 28013 0.215 45 AlCu6Mn 277(NTO) 0.003(He) 114 0.215 45 AlCu6Mn 153(UDMH) 0.003(He) 1 30015 0.020 800 TiAl6V4 - 1.123(He) 35016 0.130 576 CFK - 46.695( ¤ ) 28017 0.130 576 CFK - 40.880( ¥ ) 28018 0.301 88 CFK 280( ¦ ¤ ) 0.022( ¥ ) 1

Table15: Non-nominalRe-entryConfiguration

re-entry. So this contanttemperaturecannot be usedfor tank pressurecalculation. In thesecasesthemeantemperatureof themodelledtankliner or shellshavebeenusedastemperatureof thetankcontentsassumingthat thesmallamountsof liquids or gasesin ’empty’ tankshave thesametemperatureasthewalls.

In somecasesbeforeatankburstapressuredecayeventcanoccur. Thismeansfor exampletheseparationof themainengines.If this happensit is assumedthatall connectinglinesbetweenassociatedtanksandtheenginesarecut andthereforethesetanksaredepletedbeforebursting.Thefollowing pressuredecayeventshave beendefined:

� Destructionor separationof aFDV (fill anddrainvalve) of any tank

� Seperationof a tankitself

� Destructionor separationof an ACS (attitudecontrol system)cluster(EPB propellantand gastanks)

� Main enginesseparation(EPBpropellantandgastanks)

During the SCARAB calculationit hasbeenchecked whethersuchan event occurs. Tank andburst


pressurearecalculatedtill thefirst pressuredecayeventor tankbursting.

Theresultsareshown aspressurediagrams(tankandburstpressure)versustime for nominalre-entryinchapter4.2andfor non-nominalre-entryin chapter4.3. In generaltheseresultsshow thattankpressureincreasesonly slightly becausethe tank contentsstayrathercool. If tank burstingoccursthis happensbecauseof theheatingof theshellandthecombinedlossof strengthof thetankmaterial.

In additionto theseresultsin chapter4.3 thetankanalysisfor non-nominalre-entryhasbeenperformedassumingthatnopressuredecayin theEPBoccursaftermainenginesseparation.This is supposedto bea kind of worstcaseanalysis.It shows thatunderthis assumptionthetanksof theEPBwill burstabout20 to 30 secondsaftermainenginesseparation.

4.2 Nominal Re-entry

5

10

15

20

25

30

35

40

45

50

600 620 640 660 680 700 720 740 760 780 800

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure

Tank No. 1Tank No. 2

Figure38: NominalRe-Entry, CaseNo. 1, EPB,MON-3-Tanks

5

10

15

20

25

30

35

40

45

600 620 640 660 680 700 720 740 760 780 800

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure


Figure39: NominalRe-Entry, CaseNo. 2, EPB,MMH-Tanks


0

200

400

600

800

1000

600 620 640 660 680 700 720 740 760 780 800

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure


Figure40: NominalRe-Entry, CaseNo. 3, EPB,Helium-Tanks

0

5

10

15

20

25

30

35

40

45

50

600 650 700 750 800 850

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure


Figure41: NominalRe-Entry, CaseNo. 4, EEB,NTO-Tanks

0

5

10

15

20

25

30

35

40

45

600 650 700 750 800 850 900

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure


Figure42: NominalRe-Entry, CaseNo. 5, EEB,UDMH-Tanks


0.01

0.1

1

10

100

1000

600 650 700 750 800 850 900

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure

Tank No. 1Tank No. 2Tank No. 3Tank No. 4Tank No. 5Tank No. 6

Figure43: NominalRe-Entry, CaseNo. 6, EEB,Helium-Tanks

0.1

1

10

100

1000

600 650 700 750 800 850 900

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure

Tank No. 1 (O2)Tank No. 2 (O2)Tank No. 3 (N2)

Figure44: NominalRe-Entry, CaseNo. 7 & 8, EEB,Gas-Tanks

0

10

20

30

40

50

60

70

80

90

600 650 700 750 800 850 900

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure

Tank No. 1Tank No. 2Tank No. 3

Figure45: NominalRe-Entry, CaseNo. 9, EEB,Water-Tanks


4.3 Non-nominal Re-entry

15

20

25

30

35

40

45

50

600 610 620 630 640 650 660 670 680 690 700

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure


Figure46: Non-nominalRe-Entry, CaseNo. 10,EPB,MON-3-Tanks

15

20

25

30

35

40

45

50

600 610 620 630 640 650 660 670 680 690 700

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure


Figure47: Non-nominalRe-Entry, CaseNo. 11,EPB,MMH-Tanks


0

200

400

600

800

1000

600 610 620 630 640 650 660 670 680 690 700

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure


Figure48: Non-nominalRe-Entry, CaseNo. 12,EPB,Helium-Tanks

0

5

10

15

20

25

30

35

40

45

50

600 650 700 750 800 850 900

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure


Figure49: Non-nominalRe-Entry, CaseNo. 13,EEB,NTO-Tanks

0

5

10

15

20

25

30

35

40

45

600 650 700 750 800 850 900

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure


Figure50: Non-nominalRe-Entry, CaseNo. 14,EEB,UDMH-Tanks


300

350

400

450

500

550

600

650

700

750

800

850

600 650 700 750 800 850 900

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure

Tank No. 1Tank No. 2Tank No. 3Tank No. 4Tank No. 5Tank No. 6

Figure51: Non-nominalRe-Entry, CaseNo. 15,EEB,Helium-Tanks

250

300

350

400

450

500

550

600

600 650 700 750 800 850 900

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure

Tank No. 1 (O2)Tank No. 2 (O2)Tank No. 3 (N2)

Figure52: Non-nominalRe-Entry, CaseNo. 16 & 17,EEB,Gas-Tanks

0

10

20

30

40

50

60

70

80

90

600 650 700 750 800 850 900

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure

Tank No. 1Tank No. 2Tank No. 3

Figure53: Non-nominalRe-Entry, CaseNo. 18,EEB,Water-Tanks


0

5

10

15

20

25

30

35

40

45

50

600 620 640 660 680 700 720 740 760 780

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure


Figure54: Non-nominalRe-Entry(noPressureDecay),CaseNo. 10,EPB,MON-3-Tanks

0

5

10

15

20

25

30

35

40

45

600 620 640 660 680 700 720 740 760 780

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure


Figure55: Non-nominalRe-Entry(noPressureDecay),CaseNo. 11,EPB,MMH-Tanks

0

200

400

600

800

1000

600 620 640 660 680 700 720 740 760 780

Pre

ssur

e [b

ar]

Time [s]

Burst Pressure

Tank Pressure


Figure56: Non-nominalRe-Entry(noPressureDecay),CaseNo. 12,EPB,Helium-Tanks


4.4 Discussionof Results

Following conclusionscanbedrawn from theanalysis:

1. Nominal case:

(a) EPB (Figs. 38–40): In the nominalcasethe thrusterblock loosesits contactto the tanksafter792s simulationtime. It is assumedthatthis eventcutsthefeedlinesto thepropellanttanks.Thedifferentfragmentsgeneratedby thedisintegrationeventareshown in Chapter5(Nom.1.1.1.1–Nom.1.1.1.13).A closerlook to themainfragment(Nom.1.1.1.1)shows thatat thetime of disintegrationtherearelargemoltenareasin thewall of theEPB.This meansthat prior to the lossof the thrusterblock the free streamhadtime to heatthe interior partof theEPB,especiallythepropellanttanks.This canbeseenin Figs.38 and39. After 740s simulationtime the tank wall temperaturestartsto rise, thusreducingthe burst pressure.Before the feed lines are cut the burst pressuredecreasesbelow the pressureof the tankcontent. This indicatesa failure of the tank wall which due to the small increaseof theinternalpressurewould resultin a soft tankburstwhich is unlikely to causeseverechangesto the dynamicpropertiesof the spacevehicle. The Helium tank, which is more hiddenwithin theEPB,remainscold.

(b) EEB (Figs. 41–45): TheEEB tanksareexposedto theflow muchlater thantheEPBsincetheEEB walls aremelting later. A hole in theEEB wall canbeseenalreadyin thepictureof fragmentNom.1.1.1.1(Fig. 66). Exceptthe watertanksall other tanksareheatedonlyslightly during re-entry. The water tankson the other handareheatedvery rapidly. Thereasonis thatthewatertanksaremadeof CFRP, whichhasa low heatcapacitycomparedtothemetallicwallsof theothertanks.This leadsagainto asoft burstof thewatertankwalls.

2. Non-nominal case:

(a) EPB (Figs. 46–48,54–56): In the non-nominalcasethe thrusterblock is separatedfromthe spacevehiclemuchearlier thanin the nominalcase. This is dueto the differentmassproperties,resultingin adifferentdynamicbehaviour. In thenominalcasetheS/V attitudeisstabilizedmoreor lessin flight direction(cf. Fig. 22), in thenon-nominalcaseit is stabilizedin theoppositedirection(cf. Fig.34). Thereforetheheatloadsto thethrusterblock itself andits surroundingsis higherthanin thenominalcase.At thetime of separationtheEPBwallsarenearlyintact(cf. Fig. 92). Thetanksarestill coldandnoburstingoccurs.If it is assumedthat thethrustblock separationdoesnot resultin a depletionof thepropellanttanks,thenasoft burstingwouldoccur(Figs.54–56).

(b) EEB (Figs. 49–53): For theEEB thesituationis similar to thenominalcase.All tanksareheated,but only thewatertankswill fail.


5 DetailedDebris Characteristics

5.1 Overview

In this chaptera list of all computedfragmentsis presented,first for thenominalcase,thenfor thenon-nominalcase. Eachfragmentwasassigneda uniqueidentifier, indicating the configuration(Nom fornominal,NN for non-nominal)andthehierachylevel in thefragmentationtree.For example,Nom.1.2.5indicates:fifth fragmentafterdisintegrationof thesecondfragmentafterdisintegrationof thefirst frag-mentafter disintegrationof the completenominalATV. In addition,following dataarelisted for eachfragment:

Name: Typeof thefragment

Parent: ID of theparentfragment

Initial characteristics: Fragmentdataat thetimeof its generation

Time SimulationtimeatgenerationAltitude Altitude atoriginVelocity VelocityatoriginMass MassatoriginMaterials MaterialcompositionatoriginMax. Temperature Highesttemperatureon thesurfaceof thefragmentat origin

It follows animageof thefragmentatgenerationtime.

For fragmentswhich disintegrateor demiseit follows thetime andaltitudeof disintegrationor demise.For fragmentswhichsurvive there-entryandhit thegroundfollowing dataarelisted:

Final characteristics: Fragmentdataatgroundimpact

Time(max/min) Impacttime for max./min.ballisticcoefficient BVelocity (max/min) Velocityat impactfor max./min.BMass Massat impactProj. area(max/min) Projectedareafor max./min.BMaterials Materialcompositionat impactMax. Temperature Highesttemperatureon thesurfaceof thefragmentbeforeimpact


5.2 Nominal Case

ID: Nom.1

Name:Main bodyfragment

Initial characteristics:

Time 576sAltitude 92 kmMass 16371kgMaterials AA7075,HC-AA7075,TiAl6V4, A286,

CFRP, Liq-N2O4,Liq-MMH, Copper, Niob-C103,Inconel718,Liq-H2O, AA2219,AA6060-63

Max. temperature 870K

Figure57: FragmentNom.1:Main bodyfragment

FragmentNom.1disintegratesinto 5 fragmentsat

Time 675sAltitude 75.2km


IDs: Nom.2,Nom.3,Nom.4,Nom.5

Name:Solararray

Parent:Nom

Initial characteristics(Nom.2):

Time 576sAltitude 92 kmMass 26.5kgMaterials AA7075,HC-AA7075Max. temperature 870K

Y

Z X

Figure58: FragmentNom.2:Solararray

FragmentNom.2disintegratesinto 3 fragmentsat



ID: Nom.2.1

Name:Solararrayfragment

Parent:Nom.2


Time 583sAltitude 90.8kmMass 5.1kgParent Nom.2Materials AA7075,HC-AA7075Max. temperature 870K

Y

Z X

Figure59: FragmentNom.2.1:Solararrayfragment

FragmentNom.2.1demisesat

Time 663.5sAltitude 77.1km

It is assumed,that alsofragmentsNom.2.2andNom.2.3will demise.Correspondinglyit is followed,that also the solararraysNom.3, Nom.4 andNom.5 will demise,i.e. all solararraysarecompletelydestroyedduringre-entry.


ID: Nom.1.1


Parent:Nom.1


Time 675sAltitude 75.2kmVelocity 7525m/sMass 15501kgMaterials AA7075,HC-AA7075,TiAl6V4, A286,



Figure60: FragmentNom.1.1:Main bodyfragment

FragmentNom.1.1disintegratesinto 2 fragmentsat



ID: Nom.1.2

Name:EPM.PMtop

Parent:Nom.1


Time 675sAltitude 75.2kmVelocity 7525m/sMass 542.5kgMaterials AA2219,AA6060-63Max. temperature 900K

Y

XZ

Figure61: FragmentNom.1.2:EPM.PMtop

FragmentNom.1.2survivesthere-entrywithout furtherfragmentation.

Final characteristicsat impact:

Time(max/min) 1389s,1082sVelocity(min/max) 25 m/s,82.5m/sMass 499kgProj. Area(max/min) 12.7m , 3.3mMaterials AA2219,AA6060-63Max. temperature 870K


ID: Nom.1.3

Name:RDS

Parent:Nom.1


Time 675sAltitude 75.2kmVelocity 7540m/sMass 190.5kgMaterials AA2219,AA6060-63Max. temperature 900K

Y

XZ

Figure62: FragmentNom.1.3:RDS

FragmentNom.1.3survivesthere-entrywithout furtherfragmentation.


Time(max/min) 1190s,986sVelocity (min/max) 43.5m/s,134m/sMass 142.7kgProj. Area(max/min) 1.3m , 0.33mMaterials AA2219,AA6060-63Max. temperature 870K


ID: Nom.1.4

Name:MDPSwall fragment

Parent:Nom.1


Time 675sAltitude 75.2kmVelocity 7540m/sMass 2.7kgMaterials AA6060-63Max. temperature 900K

X

Y

Z

Figure63: FragmentNom.1.4:MDPSwall fragment

FragmentNom.1.4meltscompletelyduringre-entry. It demisesat



ID: Nom.1.1.1


Parent:Nom.1.1


Time 740sAltitude 63.8kmVelocity 7246m/sMass 14897kgMaterial AA7075,HC-AA7075,TiAl6V4, A286,



Figure64: FragmentNom.1.1.1:Main bodyfragment

FragmentNom.1.1.1disintegratesinto 13 fragmentsat



ID: Nom.1.1.2

Name:EPMdisk

Parent:Nom.1.1


Time 740sAltitude 63.8kmVelocity 7246m/sMass 345kgMaterial AA7075Max. temperature 870K

Y

Z X

Figure65: FragmentNom.1.1.2:EPM disk

FragmentNom.1.1.2survivesthere-entrywithout furtherfragmentation.


Time(max/min) 1180s,891sVelocity (min/max) 39 m/s,461m/sMass 345kgProj. Area(max/min) 3.1m , 0.077mMaterial AA7075Max. temperature 870K


ID: Nom.1.1.1.1


Parent:Nom.1.1.1


Time 792sAltitude 52.5kmVelocity 6291m/sMass 9800kgMaterials AA7075,HC-AA7075,TiAl6V4, CFRP,

A286,Copper, Liq-H2O, Inconel718,AA2219,AA6060-63Max. temperature 1600K

Figure66: FragmentNom.1.1.1.1:Main bodyfragment

FragmentNom.1.1.1.1disintegratesinto 5 fragmentsat



ID: Nom.1.1.1.2

Name:EPBthrustblock

Parent:Nom.1.1.1


Time 792sAltitude 52.5kmVelocity 6291m/sMass 566kgMaterials AA7075,HC-AA7075,Niob-C103,Inconel718,AA6060-63Max. temperature 1376K

X

Y

Z

Figure67: FragmentNom.1.1.1.2:EPBthrustblock

FragmentNom.1.1.1.2disintegratesinto 2 new fragmentsat



ID: Nom.1.1.1.2.1

Name:EPBbacksidering

Parent:Nom.1.1.1.2


Time 793sAltitude 52.3kmVelocity 6094m/sMass 394kgMaterials AA7075,Niob-C103,Inconel718,AA6060-63Max. temperature 1303K

X

Y

Z

Figure68: FragmentNom.1.1.1.2.1:EPBbacksidering

FragmentNom.1.1.1.2.1disintegratesinto 3 fragmentsat



ID: Nom.1.1.1.2.2

Name:EPBthrustblock

Parent:Nom.1.1.1.2


Time 793sAltitude 52.3kmVelocity 6094m/sMass 167kgMaterials HC-AA7075,Niob-C103Max. temperature 1396K

X

Y

Z

Figure69: FragmentNom.1.1.1.2.2:EPBthrustblock

FragmentNom.1.1.1.2.2disintegratesinto 4 new fragmentsat



ID: Nom.1.1.1.2.2.1

Name:EPBthruster

Parent:Nom.1.1.1.2.2


Time 816sAltitude 47.2kmVelocity 3824m/sMass 21 kgMaterials HC-AA7075,Niob-C103Max. temperature 1493K

X

Y

Z

Figure70: FragmentNom.1.1.1.2.2.1:EPBthruster

FragmentNom.1.1.1.2.2.1is suspectedto survive there-entryandto reachground.


Time(max/min) 1103s,1057sVelocity (min/max) 66 m/s,90 m/sMass 19 kgProj. Area(max/min) 0.14m , 0.11mMaterials HC-AA7075,Niob-C103Max. temperature 1511K (t=820s)


ID: Nom.1.1.1.3

Name:ConnectedEPBfuel tanks

Parent:Nom.1.1.1


Time 792sAltitude 52.5kmVelocity 6291m/sMass 438kgMaterials TiAl6V4, A286Max. temperature 953K

Y

XZ

Figure71: FragmentNom.1.1.1.3:ConnectedEPBtanks


ID: Nom.1.1.1.4,Nom.1.1.1.5,Nom.1.1.1.6,Nom.1.1.1.7,Nom.1.1.1.8,Nom.1.1.1.9

Name:Fill anddrainvalve

Parent:Nom.1.1.1


Time 792sAltitude 52.5kmVelocity 6291m/sMass 0.12kgMaterial TiAl6V4Max. temperature 1873K

X

Z

Y

Figure72: FragmentNom.1.1.1.4:Fill anddrainvalve

Thefill anddrainvalvesaresuspectedto survive re-entry.

Final characteristicsat groundimpact:

Time(max/min) 1905s,1178sVelocity (min/max) 14 m/s,51 m/sMass 0.12kgProj. Area(max/min) 0.0076m , 0.0023mMaterial TiAl6V4Max. temperature 1873K (t=793s)


ID: Nom.1.1.1.10,Nom.1.1.1.11

Name:EPMACS

Parent:Nom.1.1.1


Time 792sAltitude 52.5kmVelocity 6291m/sMass 11 kgMaterial AA2219, Inconel718,AA6060-63Max. temperature 1600K

Y

XZ

Figure73: FragmentNom.1.1.1.10:EPBACS

FragmentNom.1.1.1.10disintegratesinto 2 new fragmentsat



ID: Nom.1.1.1.10.1,Nom.1.1.1.10.2

Name:EPM ACSnozzle

Parent:Nom.1.1.1.10


Time 815sAltitude 47.7kmVelocity 3495m/sMass 2.3kgMaterial Inconel718Max. temperature 1297K

Y

Z X

Figure74: FragmentNom.1.1.1.10.1:EPBACSnozzle

FragmentNom.1.1.1.10.1is suspectedto survive re-entry.


Time(max/min) 1089s,1030sVelocity (min/max) 70 m/s,113m/sMass 2.3kgProj. Area(max/min) 0.010m , 0.0069mMaterial Inconel718Max. temperature 1318K (t=821s)


ID: Nom.1.1.1.12,Nom.1.1.1.13

Name:EPMrackrow

Parent:Nom.1.1.1


Time 792sAltitude 52.5kmVelocity 6291m/sMass 1541kgMaterials AA7075,A286Max. temperature 870K

Y

XZ

Figure75: FragmentNom.1.1.1.12:EPBrackrow

FragmentNom.1.1.1.12is suspectedto survive re-entry.


Time(max/min) 997s,973sVelocity (min/max) 144m/s,196m/sMass 1541kgProj. Area(max/min) 2.02m , 1.53mMaterials AA7075,A286Max. temperature 870K (t=792s)


ID: Nom.1.1.1.1.1


Parent:Nom.1.1.1.1


Time 803.5sAltitude 49.4kmVelocity 5761m/sMass 6513kgMaterials AA7075,HC-AA7075,TiAl6V4, CFRP,


Figure76: FragmentNom.1.1.1.1.1:Main bodyfragment

FragmentNom.1.1.1.1.1disintegratesinto 3 fragmentsat

Time 812sAltitude 47 km


ID: Nom.1.1.1.1.2

Name:EEBtank

Parent:Nom.1.1.1.1


Time 803.5sAltitude 49.4kmVelocity 5761m/sMass 31.5kgMaterials AA2219Max. temperature 370K

X

Y

Z

Figure77: FragmentNom.1.1.1.1.2:EEB tank

FragmentNom.1.1.1.1.2survivesthere-entry.


Time 1145sVelocity 58 m/sMass 31.5kgProj. Area 0.43mMaterials AA2219Max. temperature 870K (t=840s)


ID: Nom.1.1.1.1.3

Name:EPM ACS

Parent:Nom.1.1.1.1


Time 803.5sAltitude 49.4kmVelocity 5761m/sMass 15 kgMaterials AA2219, Inconel718,AA6060-63Max. temperature 1600K

Y

Z

X

Figure78: FragmentNom.1.1.1.1.3:EPM ACS



Time(max/min) 1397s,1074sVelocity (min/max) 27 m/s,82 m/sMass 15 kgProj. Area(max/min) 0.335m , 0.11mMaterials AA2219, Inconel718,AA6060-63Max. temperature 1600K (t=803.5s)


ID: Nom.1.1.1.1.4,Nom.1.1.1.1.5

Name:EPMrackrow

Parent:Nom.1.1.1.1


Time 803.5sAltitude 49.4kmVelocity 5761m/sMass 1540kgMaterials AA7075,A286Max. temperature 870K

Z

XY

Figure79: FragmentNom.1.1.1.1.4:EPMrackrow



Time(max/min) 1000s,977sVelocity (min/max) 137m/s,188m/sMass 1540kgProj. Area(max/min) 2.1m , 1.53mMaterials AA7075,A286Max. temperature 870K (t=803.5s)


ID: Nom.1.1.1.1.1.1




Time 812sAltitude 47 kmVelocity 5117m/sMass 6271kgMaterials AA7075,HC-AA7075,TiAl6V4, CFRP,


Figure80: FragmentNom.1.1.1.1.1.1:Main bodyfragment

FragmentNom.1.1.1.1.1.1disintegratesinto 4 fragmentsat



ID: Nom.1.1.1.1.1.2

Name:EEBtankpair



Time 812sAltitude 47 kmVelocity 5117m/sMass 40.7kgMaterials AA2219,TiAl6V4Max. temperature 319K

Y

XZ

Figure81: FragmentNom.1.1.1.1.1.2:EEB tankpair

FragmentNom.1.1.1.1.1.2survivesthere-entry.


Time(max/min) 1171s,1115sVelocity (min/max) 50 m/s,67m/sMass 40.7kgProj. Area(max/min) 0.52m , 0.43mMaterials AA2219,TiAl6V4Max. temperature 628K (t=840s)


ID: Nom.1.1.1.1.1.3

Name:EPM ACS



Time 812sAltitude 47 kmVelocity 5117m/sMass 12.7kgMaterials AA2219, Inconel718Max. temperature 1600K

X

Z

Y

Figure82: FragmentNom.1.1.1.1.1.3:EPM ACS

FragmentNom.1.1.1.1.1.3is suspectedto survive re-entry.


Time(max/min) 1355s,1088sVelocity (min/max) 29 m/s,77 m/sMass 12.7kgProj. Area(max/min) 0.225m , 0.10mMaterials AA2219, Inconel718Max. temperature 1600K (t=812s)


ID: Nom.1.1.1.1.1.1.1


Parent:Nom.1.1.1.1.1.1


Time 854sAltitude 35.9kmVelocity 2104m/sMass 5770kgMaterials HC-AA7075,AA7075,TiAl6V4, CFRP,

A286,Copper, Liq-H2O, AA2219,AA6060-63Max. temperature 1160K

Figure83: FragmentNom.1.1.1.1.1.1.1:Main bodyfragment

FragmentNom.1.1.1.1.1.1.1survivesre-entry.


Time 1020sVelocity 125m/sMass 5767.5kgProj. Area(max/min) 15.5m , 14.7mMaterials s.a.Max. temperature 1060K (t=880s)


ID: Nom.1.1.1.1.1.1.2,Nom.1.1.1.1.1.1.3

Name:Solararrayhinge



Time 854sAltitude 35.9kmVelocity 2104m/sMass 8.7kgMaterial AA7075Max. temperature 870K

Y

XZ

Figure84: FragmentNom.1.1.1.1.1.1.2:Solararrayhinge

FragmentNom.1.1.1.1.1.1.2survivesre-entry.


Time(max/min) 1190s,1020sVelocity (min/max) 46 m/s,128m/sMass 8.7kgProj. Area(max/min) 0.063m , 0.021mMaterials AA7075Max. temperature 870K (t=855s)


ID: Nom.1.1.1.1.1.1.4

Name:EPMwall fragment



Time 854sAltitude 35.9kmVelocity 2104m/sMass 12.4kgMaterial AA2219,AA6060-63Max. temperature 900K

Z

X

Y

Figure85: FragmentNom.1.1.1.1.1.1.4:EPM wall fragment

FragmentNom.1.1.1.1.1.1.4is suspectedto survive re-entry.


Time(max/min) 1607s,1077sVelocity (min/max) 19 m/s,86m/sMass 12.4kgProj. Area(max/min) 0.39m , 0.08mMaterials AA2219,AA6060-63Max. temperature 900K (t=855s)


5.3 Non-Nominal Case

ID: NN.1



Time 567sAltitude 93.5kmMass 18348kgMaterials AA7075,HC-AA7075,TiAl6V4, CFRP,

Liq-N2O4,Liq-MMH, Copper, He-280bar, Niob-C103,Inconel718,A286,Liq-H2O, N2-280bar, AA2219,Liq-UDMH, Liq-N2O4,AA6060-63


Figure86: FragmentNN.1: Main bodyfragment

FragmentNN.1 disintegratesinto 2 fragmentsat



IDs: NN.2,NN.3,NN.4,NN.5

Name:Solararray

Parent:NN

Initial characteristics(NN.2):

Time 567sAltitude 93.5kmMass 26.8kgMaterials AA7075,HC-AA7075Max. temperature 870K

Y

Z X

Figure87: FragmentNN.2: Solararray

No detailedre-entryanalysiswasperformedfor the solararrays,sinceit wassuspected,that the solararrayswill bedestroyedcompletelyasin thenominalcase(cf. fragmentsNom.2–Nom.5).


ID: NN.1.1


Parent:NN.1



Liq-N2O4,Liq-MMH, Copper, He-280bar, Niob-C103,Inconel718,A286,Liq-H2O, N2-280bar, AA2219,Liq-UDMH, Liq-N2O4,AA6060-63


Figure88: FragmentNN.1.1: Main bodyfragment

FragmentNN.1.1disintegratesinto 2 fragmentsat



ID: NN.1.2

Name:RDS+ EPM.PMtop

Parent:NN.1


Time 675sAltitude 75.4kmVelocity 7566m/sMass 761kgMaterials AA2219,AA6060-63Max. temperature 900K

Y

XZ

Figure89: FragmentNN.1.2: RDS+ EPM.PMtop

FragmentNN.1.2disintegratesinto 2 fragmentsat



ID: NN.1.2.1

Name:EPM.PMtop

Parent:NN.1.2



Y

XZ

Figure90: FragmentNN.1.2.1:EPM.PMtop

FragmentNN.1.2.1survivesthere-entry.


Time(max/min) 1434s,1063sVelocity (min/max) 26 m/s,86 m/sMass 526kgProj. Area(max/min) 13.2m , 3.3mMaterial AA2219,AA6060-63Max. temperature 900K (t=800s)


ID: NN.1.2.2

Name:RDS

Parent:NN.1.2



Y

XZ

Figure91: FragmentNN.1.2.2:RDS

FragmentNN.1.2.2survivesthere-entry.


Time(max/min) 1130s,990sVelocity (min/max) 50 m/s,125m/sMass 184.5kgProj. Area(max/min) 1.4m , 0.5mMaterial AA2219,AA6060-63Max. temperature 900K (t=820s)


ID: NN.1.1.1


Parent:NN.1.1



Copper, Niob-C103,Inconel718,A286,Liq-H2O,N2-280bar, AA2219,Liq-UDMH, Liq-N2O4,AA6060-63


Figure92: FragmentNN.1.1.1:Main bodyfragment

FragmentNN.1.1.1disintegratesinto 17 fragmentsat



ID: NN.1.1.2

Name:EPBthrustblock

Parent:NN.1.1


Time 690sAltitude 72.9kmVelocity 7541m/sMass 153kgMaterials HC-AA7075,Niob-C103Max. temperature 1017K

X

Y

Z

Figure93: FragmentNN.1.1.2:EPBthrustblock

FragmentNN.1.1.2disintegratesinto 4 fragmentsat



ID: NN.1.1.2.1,NN.1.1.2.2,NN.1.1.2.3,NN.1.1.2.4

Name:EPBthruster

Parent:NN.1.1.2

Initial characteristics(NN.1.1.2.1):

Time 693sAltitude 72.4kmVelocity 7469m/sMass 25.4kgMaterials HC-AA7075,Niob-C103Max. temperature 1051K

X

Y

Z

Figure94: FragmentNN.1.1.2.1:EPBthruster

FragmentNN.1.1.2.1survivesthere-entry.


Time(max/min) 1090s,1055sVelocity (min/max) 67 m/s,87 m/sMass 19.6kgProj. Area(max/min) 0.14m , 0.11mMaterial Niob-C103Max. temperature 1351K (t=880s)


ID: NN.1.1.1.1


Parent:NN.1.1.1


Time 798sAltitude 53.1kmVelocity 6074m/sMass 10130kgMaterials HC-AA7075,AA7075,Copper, A286,TiAl6V4,

CFRP, Liq-H2O, Inconel718,N2-280bar, AA2219,Liq-UDMH, Liq-N2O4,He-280bar, AA6060-63


Figure95: FragmentNN.1.1.1.1:Main bodyfragment

FragmentNN.1.1.1.1disintegratesinto 9 fragmentsat

Time 824sAltitude 46km


ID: NN.1.1.1.2

Name:EPBbacksidering

Parent:NN.1.1.1


Time 798sAltitude 53.1kmVelocity 6074m/sMass 158kgMaterials AA7075, Inconel718,Niob-C103,AA6060-63Max. temperature 1175K

X

Y

Z

Figure96: FragmentNN.1.1.1.2:EPBbacksidering




ID: NN.1.1.1.3,NN.1.1.1.4

Name:EPBACS

Parent:NN.1.1.1


Time 798sAltitude 53.1kmVelocity 6074m/sMass 25.8kgMaterials AA7075, Inconel718,Niob-C103Max. temperature 1180K

ZX

Y

Figure97: FragmentNN.1.1.1.3:EPBACS



Time(max/min) 1121s,1028sVelocity (min/max) 61 m/s,120m/sMass 23.7kgProj. Area(max/min) 0.13m , 0.07mMaterial Inconel718,Niob-C103Max. temperature 1588K (t=860s)


ID: NN.1.1.1.5,NN.1.1.1.6,NN.1.1.1.7,NN.1.1.1.8

Name:EPBfuel tank

Parent:NN.1.1.1


Time 798sAltitude 53.1kmVelocity 6074m/sMass 62.2kgMaterials TiAl6V4Max. temperature 1241K

X

Y

Z

Figure98: FragmentNN.1.1.1.5:EPBfuel tank



Time 1190sVelocity 50 m/sMass 62.2kgProj. Area 1.2mMaterial TiAl6V4Max. temperature 1194K (t=850s)


ID: NN.1.1.1.9,NN.1.1.1.10

Name:EPBHelium tank

Parent:NN.1.1.1


Time 798sAltitude 53.1kmVelocity 6074m/sMass 71 kgMaterials TiAl6V4, CFRPMax. temperature 593K

X

Y

Z

Figure99: FragmentNN.1.1.1.9:EPBHelium tank



Time 1122sVelocity 66 m/sMass 54 kgProj. Area 0.56mMaterial TiAl6V4, CFRPMax. temperature 1184K (t=850s)


ID: NN.1.1.1.11


Parent:NN.1.1.1


Time 798sAltitude 53.1kmVelocity 6074m/sMass 256kgMaterials TiAl6V4, HC-AA7075Max. temperature 1114K

X

Y

Z

Figure100: FragmentNN.1.1.1.11:ConnectedEPBfuel tanks




ID: NN.1.1.1.11.1,NN.1.1.1.11.2


Parent:NN.1.1.1.1

Initial characteristics(NN.1.1.1.11.1):

Time 800sAltitude 52.6kmVelocity 5466m/sMass 127kgMaterials TiAl6V4, HC-AA7075Max. temperature 1077K

X

Y

Z

Figure101: FragmentNN.1.1.1.11.1:ConnectedEPBfuel tanks

FragmentNN.1.1.1.11.1disintegratesinto 2 fragmentsat



ID: NN.1.1.1.12,NN.1.1.1.13,NN.1.1.1.14,NN.1.1.1.15

Name:Fill anddrainvalve

Parent:NN.1.1.1


Time 798sAltitude 53.1kmVelocity 6074m/sMass 0.12kgMaterials TiAl6V4Max. temperature 1873K

X

Y

Z

Figure102: FragmentNN.1.1.1.12:Fill anddrainvalve

FragmentNN.1.1.1.12survivesre-entry.


Time(max/min) 1903s,1183sVelocity (min/max) 14 m/s,51 m/sMass 0.12kgProj. Area(max/min) 0.0073m , 0.0023mMaterial TiAl6V4Max. temperature 1360K (t=811s)


ID: NN.1.1.1.16

Name:EPMACS

Parent:NN.1.1.1


Time 798sAltitude 53.1kmVelocity 6074m/sMass 13.2kgMaterials AA2219, Inconel718,AA6060-63Max. temperature 1577K

Y

XZ

Figure103:FragmentNN.1.1.1.16:EPM ACS



Time(max/min) 1217s,1093sVelocity (min/max) 43 m/s,77m/sMass 10.6kgProj. Area(max/min) 0.14m , 0.083mMaterial Inconel718Max. temperature 1600K (t=825s)


ID: NN.1.1.1.17

Name:EPM disk

Parent:NN.1.1.1


Time 798sAltitude 53.1kmVelocity 6074m/sMass 345kgMaterials AA7075Max. temperature 581K

Y

Z X

Figure104: FragmentNN.1.1.1.17:EPM disk



Time(max/min) 1060s,859sVelocity (min/max) 39 m/s,390m/sMass 345kgProj. Area(max/min) 3.1m , 0.08mMaterial AA7075Max. temperature 831.5K (t=835s)


ID: NN.1.1.1.1.1


Parent:NN.1.1.1.1


Time 824sAltitude 46 kmVelocity 4905m/sMass 6054kgMaterials HC-AA7075,AA7075,Copper, A286,TiAl6V4,



Figure105: FragmentNN.1.1.1.1.1:Finalmainbodyfragment

FragmentNN.1.1.1.1.1survivesthere-entry.


Time(max/min) 1033s,1000sVelocity (min/max) 106m/s,148m/sMass 5826kgProj. Area(max/min) 15.2m , 11.7mMaterials HC-AA7075,AA7075,Copper, A286,TiAl6V4,


Max. temperature 1121K (t=880s)


ID: NN.1.1.1.1.2,NN.1.1.1.1.3,NN.1.1.1.1.4

Name:EPM ACS

Parent:NN.1.1.1.1


Time 824sAltitude 46 kmVelocity 4905m/sMass 14.2kgMaterials AA2219, Inconel718,AA6060-63Max. temperature 1493K

Y

Z

X

Figure106: FragmentNN.1.1.1.1.2:EPMACS



Time(max/min) 1220s,1100sVelocity (min/max) 43 m/s,76 m/sMass 10.9kgProj. Area(max/min) 0.14m , 0.09mMaterial Inconel718,AA6060-63Max. temperature 1600K (t=854s)


ID: NN.1.1.1.1.5,NN.1.1.1.1.6,NN.1.1.1.1.7,NN.1.1.1.1.8

Name:EPMrackrow

Parent:NN.1.1.1.1


Time 824sAltitude 46 kmVelocity 4905m/sMass 647.3kgMaterials AA7075,A286Max. temperature 870K

Y

XZ

Figure107:FragmentNN.1.1.1.1.5:EPM rackrow



Time(max/min) 1045s,1009sVelocity (min/max) 98 m/s,143m/sMass 642.6kgProj. Area(max/min) 1.24m , 1.69mMaterial AA7075,A286Max. temperature 870K (t=860s)


ID: NN.1.1.1.1.9

Name:EPM wall fragment

Parent:NN.1.1.1.1


Time 824sAltitude 46 kmVelocity 4905m/sMass 604kgMaterials AA7075,AA2219,AA6060-63Max. temperature 900K

Y

XZ

Figure108: FragmentNN.1.1.1.1.9:EPM wall fragment



Time(max/min) 1448s,1036sVelocity (min/max) 25 m/s,115m/sMass 480kgProj. Area(max/min) 7.9m , 1.5mMaterial AA7075,AA2219,AA6060-63Max. temperature 900K (t=845s)


References

[1] FritscheB., RobertsT., RomayM., Ivanov M., Grinberg B. andKlinkrad H., Spacecraft Disin-tegration During Uncontrolled Atmospheric Re-Entry; Proc.of the 2nd EuropeanConferenceonSpaceDebris,Darmstadt,Germany, ESA SP-393,pp.581–586,1997.

[2] FritscheB., Klinkrad H., Kashkovsky A. andGrinberg E., Spacecraft Disintegration During Un-controlled Atmospheric Entry; ActaAstronautica47,Elsevier ScienceLtd, London,U.K., pp.513–522,2000.

[3] FritscheB., Klinkrad H., Kashkovsky A., Grinberg E.,Application of SCARAB to Destructive Satel-lite Re-Entries; PaperIAA-99-IAA.6.5.08, presentedat the 51st IAF congress,Rio de Janeiro,Brazil, 2000.

[4] Klinkrad H., FritscheB. and Kashkovsky A., Prediction of Spacecraft Destruction During Un-controlled Re-Entries; Proc.of theEuropeanConferenceon SpacecraftStructures,MaterialsandMechanicalTesting,Noordwijk, TheNetherlands,ESASP-468,pp.485–490,2001.

[5] FritscheB., KoppenwallnerG., Computation of Destructive Satellite Re-Entries; Paper11.06,pre-sentedat the3rdEuropeanConferenceon SpaceDebris,Darmstadt,Germany, 2001.

[6] Koppenwallner G., Modelling ATV for Re-Entry Analysis with SCARAB; HTG TN-01-1,Katlenburg-Lindau,2001.

Documents

Re-entryanalysis for the ATV with SCARAB Draft Final ...emits.sso.esa.int/...RD3-FinalReport-ATV-Re-entry-Analysis-SCARAB.pdf · Re-entryanalysis for the ATV with SCARAB Draft Final