Going to the Water - Keck Institute for Space Studies · Power System Ice Descent Method Thermal Control Autonomous Navigation & ... •Deposit lander electronics •Relay telecom

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

8

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

9

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

10

IceMobility– Communications

ProbeTelecom

Tether

RFTx Only

Tx/RxAcoustic

RFCommunicationsiniceisfeasible• Dataratedependsonicetemperaturedependentattenuation• Releasedpuckscanstoreandforwarddata

Requiresstand-alonepower

Tetherallowsmaxbandwidth• MechanicalstrengthinEuropan iceisunknown

Combinepucksandtether(andacoustic)?

11

CommunicationsinIceandtoEarth

OrbiterConfiguration• 2mantenna• 100WTWTA• X-band

LanderConfiguration• 27dBi surfaceantenna• 4WRF• X-band

ProbeConfiguration• 5comm pucks• Turbocoding• 100MHz

12

ScienceCommScienceOps

ScienceTransmit

AutonomousGuidanceNavigationandOperations

NavigateRadar/Sonar

DifferentialHeatingDifferentialJetting

PuckReleaseReleasePuckAnchorPuck

TransmitCheckout

IceDescentMelt

WaterJetandCutUnfurlTether

SensePosition/OrientationTx HousekeepingData

13

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

15

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

16

OceanAccessandMobility:FourScienceSegments

4- FreeFall&EndOfMission

CutTether

3- UnderwaterVehicle Ops

BuoyantoperationScienceOpsMobilityOps

2- Probe FullySubmersed

DeployoceanprobeTetheredOps

1- Probe NoseInAnchor

ImageoceanSamplewater

17

BeginwithEuropaLandersystemsandmassparameters• SLSlaunchwithsamedrymassasLanderconceptproject• SametrajectorydesigntoJupiterandEuropa• SameDeorbitsystem• SameMasstothesurface(butnotskycrane landersystem)

Beginwithknownpowersources(radioisotope)• Whatadvancescanwemake?

Baseline10Kmicethickness• BaselineIcetemperatureprofile,saltcontent

Setapproximatelytwo-yeartimeforicetravel

DesignAssumptions

EuropaLanderMissionDesign

18

ConceptualDesign

19

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

20

EuropaClipper EuropaLanderConcept

EuropaOceanExploration

Poweredlandingto100maccuracy• Terrainrelativenavigation• HazarddetectionLIDAR

Highresolutiondescent/surfaceimaging

Surfaceoperations• Cuttingandhandlingoficeandsaltsattemperature

Organic/inorganicquantificationatsurface

Seismometersensingofcrustalmotion

EnergySource

BiologicallyEssentialElements

LiquidWater

APotentialforLife

21