SpaceRadiationProtectionduringNASAExplorationClassMissions
KerryLeeSpaceRadiationAnalysisGroupOperationsLead
NASAJohnsonSpaceCenterHouston,TX
Outline
• SRAGOperationsandInstrumentationonISS• SRAG’spurposeistoprotectastronautsfromradiationexposure
• ExplorationMissionsandOperations• MeasurementsvsModel• RadiationHazardMitigationPlanning
• MPCV*RadiationSystemSensors
• SpaceWeatherNeedsforExplorationClassmissions
*Orion=MPCV=Multi-PurposeCrewVehicle
ISSInstrumentation
• CPDS– ChargedParticleDirectionalSpectrometer
• REM– RadiationEnvironmentMonitor
• ActivedosimeterwithUSBinterface
• TEPC– TissueEquivalentProportionalCounter
• LocatedinISSServiceModule• IV-TEPC– newTEPCdetector
• MovesaboutISSevery4-6weeks
• ISS-RAD– RadiationAssessmentDetector
RadiationEnvironmentMonitor(REM)TheTimepix Detector
§ DevelopedasaHighEnergyPhysicsapplicationofmedicalimagingtechnology
§ HybridPixelDetectorwithindependentcountingandreadoutcircuitryineachpixelfootprint
§ 256x256pixelgridwithtotalareaof2cm2
PixelDetectorImagefromMedipix collaborationwebsite:http://medipix.web.cern.ch/medipix/img/medipix2/web_flipchip.gif
PixelDetectorTechnology
ExplorationMission(EM)ClassMeasurementsandSimulation
ExplorationFlightTest1– Dec5,2014
Credit: NASA
L
R
GoogleEarthVideo– EFT-1Flight
EFT-1MissionAnalysis
• Trajectory:EFT-1ApproximatedTrajectory
• Shields:FullvehicleCADmodel• Points:BIRDRAMs1and2,BIRDDetectorsLeftandRight
• TrappedRadiation:AP8/AE8Model
• GCR:Badhwar-O’Neill2014Model,December5,2014
• RadiationTransport:HZETRN2015
BIRDLeftModel
BIRDLeftModelvsData• DataisinmicroGy andmodelincGy
• 4ordersmagnitudedifference
• ModelslightlyunderpredictsGCRregions• 10sofpercent
• Modelsignificantlyunderpredictstrappedradiationregions
• Factorof2-3
ModelvsDataforeachEFT-1Measurement
ShieldFile Modeled(mGy) Measured(mGy)BIRDLeft 5.57 17.9BIRDRight 5.94 15.7BIRDRAM1 6.81 15.1BIRDRAM2 6.18 13.5
EM-2MissionAnalysis
• Trajectory:HybridTriple
• ShieldPoint:Crew1ChestLocationinOrionSeat1ofEM-2Vehicle
• Trapped:AP8/AE8
• GCR:Badhwar-O’Neill2014,August2010• ExpectedtobesimilartoAugust2021whichisEM2schedulelaunchdate
• RadiationTransport:HZETRN2015
EM-2MissionOption:FreeReturnHybridTriple
Pre-Decisional:InternalNASAUseOnly 14
(4)Trans-LunarInjectionOrion
(5)OTCManeuversOrion
(8)Entry&Landing
(7)RTCBurnOrion
Notional
(1) Launch(2) ARB ICPS
(3)ICPSDisposal
(6)FreeReturnFlyby(noburn)Orion
1-2)LEOparkingorbit,1-2orbitcheckout,andICPSApogeeRaiseBurn(ARB)demonstration3)OrionseparatesafterARB,achievessafeseparationdistance,ICPSperformsdisposalburn4)OrionflighttestsystemcharacterizationoccursinHEO(16-24hrs),TLIperformedbyOrion6)Freereturnflyby,noOrioncriticalburnsrequired8)Nominalmissionreturnandcis-lunarentryvelocitytargetingSanDiegovicinity
Considerations• Achieveslunarvicinity• MaintainsLEO/HEO
checkoutopportunity• WithinexistingOrion
capabilities• LikelywithinICPS
capability
EM-2ProposedHybridTripleTrajectory
• 3passesthoughtrappedradiationbeltscontribute~2/3ofmodeleddose• 12daysofGCRcontributes~1/3ofmodeleddose
FutureExplorationMissionAnalyses
• Needtoevaluatehundredsofpotentiallaunchtrajectoriescoveringthefulllaunchwindow
• In keepingwiththeALARAprinciplewewillrecommendtrajectorieswiththelowestexposures
• Usethebesttrappedenvironmentmodelwiththelatestdata(IRENE)
• UseEM-1Mission(December2019launch)measurementstocalibratepredictioncapabilitiesforfutureEM-Xmissions
MPCVRadiationSystem• HybridElectronicRadiationAssessor(HERA)
• Activeinstrumentprovidestelemetereddatastream
• Systemconsistsoftworedundantstrings• Eachstring- 1PowerUnitand2SensorUnits
• RadiationAreaMonitors(RAMs)• PassivedetectorsfromShuttleandISSheritage
• CrewPersonalActiveDosimeter(CPAD)• Activedosimeterprovidesindividualdosimetric measurement
• Dataretrievedafterthemission
HERAVehicleLocations
HPUs
HSUStarboard
HSUPort
HSUinshelter
HSUFwd Bulkhead
MPCVRadiationMitigationPlanning
• HERAsystemisconnectedtotheCautionandWarningSystem• AudiblealarmsoundswhenHERAthresholdisexceeded• IfgroundcommunicationisavailableRadiationConsoledeterminesifshelteringisneeded,otherwisecrewwillshelteruponHERAalarm
• AcuteradiationimpactassessmentmodeledbasedonHERAmeasurements
• StowageconfigurationoptimizedbasedonHumanintheLoop(HITL)test• HITLtestconsistedofmanysimulated4personcrewsinthemediumfidelitymockupatNASA/JSC
• Abouthalfofthetestsubjectswereastronauts• Noneofthetestsubjectshadeverseentheprocedureandmostwereunfamiliarwiththemockuplayout
• Averagetimetoreconfigurethecabinwasabout30minutes
Originalstowageconfiguration
D
E
F
A
B
Stowagere-configurationbasedonHITLtest
StowageRe-configurationModelResults• SRAGusedstowageconfigurationusedinHITLtest
• 11CTBsand3halfCTBsand10canisters(totalmass=630lb)• 6CTBsontopofbacksofseats1&2overshelter(baysDandE)• 3CTBsinfrontofshelterunderDUs• OnehalfCTBonthesidesofshelter• Added2suitbags(50lb each)onachsideoftheshelter(total4bagsof200lb)• 10canisters(9inODand9.5inlong)insideWMSonthesidewallsharedwithBayD
Crew 1 Crew2 Crew3 Crew4CrewinSeats 208mSv 191mSv 268mSv 230mSvHITLconfig (630lb +suitbags) 69mSv 83mSv 79mSv 71mSv
WholeBodyEffectiveDose*RadiationAnalysisResultsforasimulated1972KingSpectrumSPE
*EffectiveDoseasdefinedinNationalCouncilonRadiationProtectionandMeasurements(NCRP)ReportNo.132
Summary
• EstablishedMPCVconceptofoperationsforradiationcontingencyevent• Protectionispossiblebelowrequiredlimitwithoutflyinganyparasiticmass• Finaldetailsarebeingworked
• MPCVradiationinstrumentationisbuilt• HardwaretestingonISSinthenearfuture
• SRAGOperationalneedsforfutureexplorationmissions(inchronologicalorder)
• UselatestIRENEreleasetoevaluateEM-1andEM-2trajectoriesandcomparewithdata
• ForecastingtoolsformoreleadtimeonSPEs• All-clearstillavalidoperationalmethod– nogeomagneticfieldprotectionforGatewaymissions
• OffSun-EarthlineSPEforecasting(all-clear)• EuropaandMarsmissions(2030s)
Acknowledgements
• SpaceRadiationAnalysisGroup– REMandHERAanalysiswork• MartinKroupa,StuartGeorge,Nic Stoffle,ThomasCampbell-Ricketts,RyanRios
• AESProgramforfundingHERAdevelopment• JasonCrusan,CatherineMcleod,ScottWheeler,MichaelEcord andentireHERAdevelopmentteam