OriginsSpaceTelescope(OST)MissionConceptOverview

InstrumentInterfaceandFace-to-FaceMeetingsScienceandTechnologyDefinitionTeam(STDT)A.Flores,MissionSystemsEngineer(MSE)

NASAGoddardSpaceFlightCenter8800GreenbeltRoad,Greenbelt,MD20771

June13,14&15,2017

GSFCDesignTeamMembersOSTGSFCDesignTeamMembersareasfollows:

• StudyScientist:David“Dave”Leisawitz• DeputyStudyScientist:JohannesStaguhn• StudyManager(401):RuthCarter• SystemArchitect/Technologist(542):MikeDiPirro• MissionSystemsEngineer(MSE)(599):AnelFlores• InstrumentSystemEngineer(ISE)(592):James“Jim”Kellogg

andEdAmatucci• Optics(551):JoeHowardandJamesCorsetti• Cyro (541):EdCanavan• Mechanical(543):,GregMartinandAndrewJones• Thermal(545):LouFantano

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• ACS(591):EricStoneking• FlightDynamics:DaveFoltaandCasandra“Cassie”Webster• Propulsion:Daniel“Dan”Rampspacker• Electromechanical(544):RajeevSharma• StructuralAnalysisandModelling(542):TimCarnahan• Materials(541):CarleySandin,KevinHodges• Detectors(553):KevinDenis• ElectricalandDataSystems(564):DamonBradleyandPorfirio

Beltran• IntegrationandTest(568):SusannaPetro• MissionOperations&GroundSystem(581):SteveTompkins

OSTMissionGoalsTheOriginsSpaceTelescopeisthemissionconceptfortheFarInfraredSurveyor,astudyindevelopmentbyNASAinpreparationforthe2020AstronomyandAstrophysicsDecadalSurvey

OSTisplannedtobealargeaperture(8-mto15-m),actively-cooledtelescope(~4K)coveringawidespanofthemid- tofar-infraredspectrum.Itsspectrographswithenablethree-dimensionalsurveysoftheskythatwilldiscoverandcharacterizethemostdistantgalaxies,exoplanetsandtheouterreachesofourSolarSystem.TheobservatoryisplannedtobeplacedintheSun-EarthL2,similartoJWST.PrincipalScienceThemesinclude:• TracingtheSignaturesofLifeandtheIngredientsofHabitableWorlds• UnveilingtheGrowthofBlackHolesandGalaxiesoverCosmicTime• ChartingtheRiseofMetals,Dust,andtheFirstGalaxies• CharacterizingSmallBodiesintheSolarSystem• Measuringexoplanetbiosignaturestosearchforsignsoflife

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Top-LevelMissionRequirements• ObservatorytoAccommodatethefollowingfive(5)instruments:

• MediumResolutionSurveySpectrometer(MRRS)– JPL• HiRes(Far-IR)Spectrometer(HRS)- GSFC• HeterodyneInstrument(HI)– Europe• FIRImager/Polarimeter(FIP)– GSFC• MID-IRImagerSpectrometer/Coronagraph(MISC)– JAXA

• InstrumentWavelengthCoverage:6to600microns

• MissionDuration:5yearsnominalwithupto10yearsextended

• BaselineObservatorytofitintoa5-mlaunchvehiclefairing,becausethisfairingsizeisrathercommonandisexpectedtobeavailablefortheforeseeablefuture.

• Telescopesize:thelargesttelescopecompatiblewithalaunchina5mfairing,withtheunderstandingthatit’saperturewouldbeapproximately9metersindiameter

• Telescopetype:threemirror,unobstructed,off-axisfield

• Observatorywillbeplacedinappropriateorbittobeabletoconducttherequiredscienceobservations

• Observatoryoperatingtemperature:4to4.5K

• ObservingStrategies:underdevelopment,TBD

• Appropriatelaunchvehicletoplacetheobservatoryintheproperorbit

• ObservatorywilltransmitthesciencedatatotheEarthMissionandScienceOperationsCenter’s(MOCandSOC)

• Serviceableobservatory:theinstrumentswillbedesignedinserviceablemoduleswithgrapplesandfixturesforservicing.AmodulardesigncouldbehelpfulinI&Tduetotheaccessibilityoftheinstruments.Wewillassumethepropellantfuelwillalsobeserviceable.Aservicingmission forOSTitself;however,isnotrequiredtobedesignedatthisstage.

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Top-LevelDerivedRequirements• Orbit: Sun-EarthL2

• MissionClassification: ClassA,generallyfullyredundantandcrossstrapped

• LaunchVehicle(LV):VulcanAces,FalconHeavyorsimilarLVcapability

• LVFairingSize:5-mAtlasVfairingorsimilar

• LaunchDate:Mid-2030’s

• OpticalTelescopeAssembly(OTA)Temperature:4K Activelycooledusingcryocoolers

• Baselinenon-articulating(i.e.,fixed)telescope:articulationcouldbeconsideredifitisrequiredbythesciencerequirements.However,anarticulatingtelescopewillrequireagimbalmechanism,whichhastobecold.Suchamechanismwilladdcomplexity,costandrisk.

• InstrumentstobedesignedwithappropriateinternalredundancyandLevel1components.

• Instrumentelectronicswillbeseparate,locatedinthespacecraftbus(warmside),fromthecoldportionoftheinstrumentslocatedintheInstrumentAccommodationModule(IAM)behindtheOTAonthecoldsideoftheobservatory

• OSTwillprovide~4Kfortheinstrumentsandanintermediate~20Kzoneforreadoutelectronicsusingatotalofeightcyro-coolers.

• Theinstrumentswillhavetoshareatotal100milli-wattsonthetelescopecold-sidenotnecessarilyequally.

• TotalobservatorypowerrequiredisTBDwattsatBOL.

• Consumables:suchaspropellantfuel,willbesizedfor10years

• OSTwillattempttoachieveattitudecontrolrequirementssimilartoJWST(oracombinationwithWFIRST)ifpossible,although,theserequirementswillberevisedwhenalloftheinstrumentsrequirementsareknown. 5

OSTInstrumentOpticalInputsSummary

Yellowcellshighlighttelescopedesigndrivers

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NotionalUnobstructed,Off-AxisField,Observatory

Activelycooled(~4K)BaffleAssembly

(notshownonright,seeinsetbelowfor

concept) Incidentlight

9.1-mApertureDiameterPrimaryMirror(~4k),Threemirror,unobstructed,off-axisfield

SunshieldFive(5)Layers*0.75-mSpacing

Fixed(Deployable,Non-articulating)Optical

TelescopeElement(OTE)

ColdSide(InnerLayer

~35K)

WarmSide(250– 300K)

DeployedObservatoryConfiguration

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+X

+Z

+Y

Sun

*Assumesparallelspacingbetweenlayers.AngularspacingbetweentheSunshieldlayersisalsobeingexplored

FieldofRegard+5˚to-45˚PitchoffSunline±180˚YawaboutSunline

±5˚RollaboutLineofSight(LOS)

UnobstructedObservatoryAftView

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NotionalRadiatorNotionalSolarArray

HighGainAntenna(HGA)(BehindRadiator)

Spacecraftbus

OutermostSunshieldLayer

FieldofRegard-5˚to-45˚PitchoffSunline±180˚YawaboutSunline

±5˚RollaboutLineofSight(LOS)

DeployableTowerAssembly(DTA)(segmented)

UnobstructedObservatorySideViewsShowingLightTrace

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LightRayTrace

InstrumentAccommodationModule(IAM)

DeployableTowerAssembly(DTA),Segmented

4.4m

PrimaryMirror(PM)

PMtoattachtoIAMwithatwo-AxisGimbal(TBD)

UnobstructedObservatoryTop-View

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DimensionsinMeters25.7m

14.8m

InstrumentAccommodationModule(IAM)

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FIPMRSS

MISC HRSRayTrace(ingreen)

HIHIRayTrace(inblue)

TelescopeFocalSurface

HRS

Cut-AwayViewshowingInstruments

HI&HRSInstrumentRayTracesintheIAMandIAMTop-view

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IAMTop-view

HIRayTrace

IAMAft-View

LookingFWD

HRSInstrument&ItsRayTraceFIP

ObservatoryROMMassEstimate

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InstrumentandFlightSystemmassesare

preliminaryandrelativelyimmature

OSTInstrumentandAccommodationRequirements

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InstrumentAttitudeControlSystemQuestionnaireResponses

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AttitudeControlSystem

• DrivingRequirements• AbsolutePointing:44mas(MISC)• OnboardPointingKnowledge:30mas(MRSSInertialPoint)• Jitter:22masRMS(MISC)• ScanningRate:100arcsec/sec(MRSSLargeSurvey)

• Assumptions• MomentsofInertia:[120,000170,000100,000]kg-m^2

• 2xJWST(tillweknowbetter)• MomentumAccumulation450Nms/day

• At45-degpitch• “Compact”sunshield• Totalspecularreflection• Masscenterassumed[3.00.04.0]fromsunshieldmajorfoldcenter• Lookingintotechniquesforreducingaccumulationrate

• Tailorsunshieldreflectivity?• Trimtab?

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SolarRadiationTorqueVs.Pitch

OSTOpticalPerformanceBudget

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FutureWorkandTrades

• CompleteinitialOTEdesigninclusiveofdeployment,inparticular.Asitsdesignprogressesdetermineitsstructuralfrequencyisadequateinthedeployedconfiguration.• CompleteIAMandSpacecraftbusinitialdesigns.• DefineconceptpackaginganddeploymentschemesfortheSunshieldandBaffleAssembly• CompleteinitialdesignsfortheDeployableTowerAssembly(DTA)andtheIAM’shingemechanism.ResolvewhethertheDTAneedstobelocatedorpartiallylocatedinsideofthespacecraftbus.• ExploreangularspacingbetweenSunshieldlayers.• CommenceaStructural,Thermal,Optics,andPointing(STOP)analysis.• DetermineobservatoryCenterofPressureandCenterofGravityforstability.• Singleordualaxissolararraygimbaltrade.

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IssuesandConcerns

• Packingofthetelescopeassemblyremainsachallengeinordertogeteverythingtofitwithinthe5-mfairing.Totalobservatoryvolume,massandpowerremainconcerns.• TheOTEarealmassisverypreliminaryandisassumedtobe~40kg/m2.JWST’sOTEarealdensityis~68kg/m2.

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Acronyms

ConOps– ConceptofOperations

DTA– DeployableTowerAssembly

FIP– FarInfraredImager/Polarimeter

FOV– FieldofView

HGA– HighGainAntenna

HI- HeterodyneInstrument

HRS- HighResolution(Far-IR)Spectrometer

IAM- InstrumentAccommodationModule

ISE– InstrumentSystemsEngineer

JWST– JamesWebbSpaceTelescope

LOS– LineofSightorLossofSignal

MISC- MID-IRImagerSpectrometer/Coronagraph

MCWG– MissionConceptWorkingGroup

MOC– MissionOperationsCenter

MRSS- MediumResolutionSurveySpectrometer

MSE– MissionSystemsEngineer

OST– OriginsSpaceTelescope

OTE– OpticalTelescopeElement

PM– PrimaryMirror

SOC– ScienceOperationsCenter

STDT– ScienceandTechnologyDefinitionTeam

STOP- Structural,Thermal,Optics,andPointinganalysis

WFIRST– WideFiledInfraredSurveyTelescope

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Back-upSlidesUnobstructedObservatorySideViewsShowingtheSpacecraftBusArealDensityforJWSTAftViewoftheInstrumentAccommodationModule(IAM)MRSSandHIInstrumentVolumes

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UnobstructedObservatorySideViewsShowingtheSpacecraftBus

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+X +X

+Z +Z

HGAlocatedbehindradiator

ArealDensityforJWST

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IAMTop-ViewWithoutAftIAMHosuing

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TelescopeFieldofView(FOV)Layout

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