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GoingtotheWater
ChallengesinDesigningaMissionthatTravelsthroughEuropa’sCrust:Deployment,Operations,Communication
TomCwikJetPropulsionLaboratory,CaliforniaInstituteofTechnology.
KISSStudyOctober9-12,2017
Copyright 2017 California Institute of Technology. U.S. Government sponsorship acknowledged.
EnergySource
BiologicallyEssentialElements
LiquidWater
Time
APotentialforLife
2
FromEuropan orbit:deorbit,descendandland,establishasurfacesystem,travelthroughtheice,entertheocean,anddeterminewhether-or-notthereisextantlife
0 km
-10 km
LandingPhase
Sub-Surface Communications
Electronic
Energy ManagementInstruments
IceMobilityPhase• MobilitytoOcean• Communicationstosurface• ScienceInstrumentation
Sub-Surface Communications
Electronic
Energy ManagementInstruments
OceanAccessandMobilityPhase• Entryintooceanatice-oceaninterface• Exploreiceinterfaceandopenocean• Maintainplanetaryprotection
SurfacePhase• Releaseprobeintoice• Communications:DTEand/ortoorbiter;Tetheredorwirelesstoprobe• Maintainoperationsinradiation
3
Europan IceProbeTradeSpaceLandingPhase SurfaceandIcePhases OceanAccessPhase
Descent method
Landing Precision
Landing Method
Deorbit, Descent and
Landing
Nose in
Ice-Surface access
Underwater vehicle
Ocean Science
Method
Packaging
Energy Conversion
Cutting
Water Jetting
Melting
Passive
Active
Passive Nav
Active Nav
Power SystemIce Descent
MethodThermalControl
Autonomous Navigation & Operations
Autonomous Operations
Surface Comm
Subsurface Comm
Ocean Comm
Communications
4
MeltProbe• Thermalenergymeltsiceaheadandalongprobe• Powercanbeaboardprobeortransferredbytetherfromsurface
• Rateoftraveldependsonamountofthermalenergy
• WaterJets canbeaddedtofurthermelticeandmovemeltwater– electricalenergyneededtodrivepumps
MechanicalCutting• Electricalenergydrivesbladetoshaveice• Chipsneedtobemovedfromfrontofprobe
IceDescent
Zimmerman,JPL2001
Honeybee,Inc5
Kaufmanetal
Amountofthermalenergyneededtomeltice:• Aamotmodelprovidesfirstorderrequirementsvsmeltrate• Dependentondiameterandlengthofprobe• Assumptions
• TemperaturevsDepth• ThermalConductivity,SpecificHeat&IceDensityvsTemperature• SaltContent• Sublimation(especiallyaticeinterface)• Viscousfriction,tethereffects,saltlayering,voids,…
IceMobility– MeltProbePower
Weiss, Planetary and Space Science 56 (2008) 1280–1292 Chyba,ICARUS134,292–302(1998)6
IceMobility– DaysforMeltProbetoTravel10Km
10kmdepthreachedinhalfthetimeifsaltyintrusionpresent
PureH2OiceMgSO4ice
StoneAerospace7
IceMobility– WaterJettingandCutting
PuO2 pellet (Heat Source)
Pump
Heat Pipe
Water Jet
Inadditiontomeltingiceformobility,needto• Travelthroughpotentialsedimentlayers• Forcesedimentandmeltwaterpastprobe
Include• Waterjettingbypumpingandejectingmeltwateratnose• Cuttingwithmotorizedbladeandremovingchips
Requireselectricalpowerdrawnfromthermalenergy• BalanceofRTGelectricalgenerationandthermal
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Blade
IceMobility– HeatandElectricSource
Type
Nuclear
Reactor
ASRG (Stirling)
RTG (Thermo-Electric)
GPHS
Pellets or other (new)
Stored
Battery
Fuel Cell
Fly-wheelSolar
Rationale: 9 year mission life necessitated active power generation Rationale: Energy
density and form factor would necessitate new PuO2 pellets
General PurposeHeat Source (GPHS) Module
Rationale: Solar is deemed insufficient for zeroth order thermal energy needed to melt ice
27GPHSBlocks6.75kWthermal
1.57 m
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ProbeThermalConfiguration
Power
Electronics (C&DH and Nav)Science Payload
(submersible)
Comm (5 pucks)
Cut and Jet(Rotary bit with water jets) ~ -20 to 50 C, 45 W
> 50 C
< 1100 C Needs > 1000 W heat from source
~ -34 to 70 C? Non operational Temperature?
Thermal Zone 3
Thermal Zone 2
Thermal Zone 1
Shunt FinThermal Zone 4
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IceMobility– Communications
ProbeTelecom
Tether
RFTx Only
Tx/RxAcoustic
RFCommunicationsiniceisfeasible• Dataratedependsonicetemperaturedependentattenuation• Releasedpuckscanstoreandforwarddata
Requiresstand-alonepower
Tetherallowsmaxbandwidth• MechanicalstrengthinEuropan iceisunknown
Combinepucksandtether(andacoustic)?
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CommunicationsinIceandtoEarth
OrbiterConfiguration• 2mantenna• 100WTWTA• X-band
LanderConfiguration• 27dBi surfaceantenna• 4WRF• X-band
ProbeConfiguration• 5comm pucks• Turbocoding• 100MHz
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ScienceCommScienceOps
ScienceTransmit
AutonomousGuidanceNavigationandOperations
NavigateRadar/Sonar
DifferentialHeatingDifferentialJetting
PuckReleaseReleasePuckAnchorPuck
TransmitCheckout
IceDescentMelt
WaterJetandCutUnfurlTether
SensePosition/OrientationTx HousekeepingData
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Probestart-upactivity• ReleaseEuropan probeintoice• Controlinitialsublimationatice/saltsurface
Surviveradiationthroughmissionlife• Useicetoprotectelectronicsfromradiation• Meltelectronicspackageintoice
Communication• DirecttoEarthorthroughOrbiter• ToandfromEuropan iceprobe
SurfacePhaseFunctions
Surface TelecomDirect to Earth
Orbiter RelayPhased Array
Gimbaled Flat Plate Array 14
SurfacePhase:InitialAccessintoIce
SOL2• Meltcutandwaterjet~meters• Depositlanderelectronics• Relaytelecomcheckout• Scienceinstrumentcheckout
SOL1• Systemcheckout• Initialmelt,cutandwaterjetoperations
SOL0• Lowerandlevel• InitialSystemcheckout• Installcapatsurface
SOL3ton• Melt,cutandjet• Unfurltether• Releasepuck• Transmitscience
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LandingPhase
Hazard Avoidance Target
Altitude Correction Target
Hazard Detection
Hazard Avoidance
Powered Approach
Altitude Correction
Powered Approach Target
Hazard Detection Target
DeorbitInitial
Localization
//
Coast
SRM Ignition SRM Burnout
DOS Jettison & Avoidance
Ready forPowered Approach
NOT TO SCALE
⌀100 m
Deorbit– Descent– Landing(DDL)
EuropaLanderHeritage
EliminationofSkycrane
PriorKnowledgeofLandingSite
Priorknowledgeoficethickness
Ready forInitial Localization
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OceanAccessandMobility:FourScienceSegments
4- FreeFall&EndOfMission
CutTether
3- UnderwaterVehicle Ops
BuoyantoperationScienceOpsMobilityOps
2- Probe FullySubmersed
DeployoceanprobeTetheredOps
1- Probe NoseInAnchor
ImageoceanSamplewater
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BeginwithEuropaLandersystemsandmassparameters• SLSlaunchwithsamedrymassasLanderconceptproject• SametrajectorydesigntoJupiterandEuropa• SameDeorbitsystem• SameMasstothesurface(butnotskycrane landersystem)
Beginwithknownpowersources(radioisotope)• Whatadvancescanwemake?
Baseline10Kmicethickness• BaselineIcetemperatureprofile,saltcontent
Setapproximatelytwo-yeartimeforicetravel
DesignAssumptions
EuropaLanderMissionDesign
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ConceptualDesign
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Power(New MicrosphereRadioisotope Based Thermoelectric Generator)
Electronics (C&DH and Nav)
Science Payload (submersible)
Comm(5 pucks)
Drill and Jet (Shaving bit with
water jets)
Ice Probe CBE Mass (Kg)
CBE Power (We)
Total Probe 210.8 597.6Navigation 4.59 11.4C&DH 1.50 10.0Power 33.26 4.0 Telecommunication 5.55 30.0Drilling / Water Jet 16.00 400.0 Submarine payload 26.70 27.2Structure 112.00 5.0Thermal 11.20 110.0Margin (%)* 41 29
*Massmargincalculatedagainst335KglandedmassallocationforEuropa LanderClassDDL*Powermarginbasedon836WEOL(9years)
7KWth Main+1KWth NosePowerSources
Withnewlydevelopedpelletthermalsource
Power (GPHS based)
4 m
WithexistingGPHSthermalsource
IceshellstructurebyRADAR• Resolutionof+/-10m@3kmdepthand+/-100m@30kmdepth
Detailedtopographicsurfacemap• At50mwithhigherresolutionregions
Surfacethermalmap• Identificationofhighertempanomalyzonessuggestingrecentup- wellingorcryo-volcanism
Mappingimagespectroscopy
Lookingahead:Whatwewillknowandhaveshown
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EuropaClipper EuropaLanderConcept
EuropaOceanExploration
Poweredlandingto100maccuracy• Terrainrelativenavigation• HazarddetectionLIDAR
Highresolutiondescent/surfaceimaging
Surfaceoperations• Cuttingandhandlingoficeandsaltsattemperature
Organic/inorganicquantificationatsurface
Seismometersensingofcrustalmotion
EnergySource
BiologicallyEssentialElements
LiquidWater
APotentialforLife
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