AProbeMissiontoTraceWaterfromInterstellarCloudstothe

SolarSystemAProposalSubmittedtotheNASAAPROBES2016Call

PaulGoldsmith,PIJetPropulsionLaboratory,CaliforniaInstituteofTechnology

TedBergin,PerBjerkeli,DominiqueBocklée-Morvan,PaolaCaselli,Maryvonne Gerin,AntoineGusdorf,DaveLeisawitz,Darek Lis,GaryMelnick,KarinOberg,JorgePineda,NealTurner,KarenWillacyCo-I’s

TracingWaterfromInterstellarCloudstotheSolarSystem

• UnderstandingtheoriginsofthewaterontheEarthandotherhabitableplanetsrequiresfollowingthismolecule’strailfrominterstellarcloudstodensecoresinwhichnewstarsform,tothe diskssurroundingtheyoungstarsandinwhichplanetsform,andfinallytooursolarsystem.

• Herschelobservationshaverevealedwater’subiquityinalloftheseregions,especiallyinthesolarsystemwhereitisfoundincomets,asteroids,satellites,aswellasplanetaryatmospheres.

Highspectralresolutionstudiesoftherotationaltransitionsofwateranditsisotopologues (especiallyHDO)areessentialfortracingwater’sformation,itsroleasacoolant,itsprocessinginavarietyofenvironments,anditsrelationshiptoicesondustgrainsurfaces.

Thelinkages betweenthesedifferentstagesinthewatertrailhavebeenemphasizedbyrecentstudiesaddressingwaterdeliveryfromcorestodisks(Furuya etal.2016,Astron.Astrophys.Inpress)andfromaprotostellar disktooursolarsystem(Cleeves etal.2014,Science,345,1590)

FourInterrelatedPhasesoftheWaterTrail

WaterEmissioninOrion

Offset(arcseconds)

GroundState(557GHz)EmissionDominatedbyBroadOutflow

Herschel

ExcitedState–Thermal&MaserEmission

WaterasTracerofDenseCoreKinematics

Water:demandingexcitation=>tracersinnermost,densestregionsC18O:easytoexcite--tracesoverallcoreanditsmotions

Cold(8-12K),compact(0.1pc)dense(103-107 cm-3)Precursorstonewstars;shouldbecollapsingWhatisthevelocityfieldincollapsingcores?

Allmodelshave~samen(r)butvastlydifferent v(r)

Keto,Caselli,Rawlings2015

Larson-PenstonSingularIsothermalSphere

UnstableB-ESphere

H2O C18O

OnlytheQuasi-EquilibriumBonnor-EbertSpheremodelreproducesobservationsofL1544

L1544H2O557GHzdatafromHerschelHIFINotevelocityresolution Theoretical

Models

WaterLinestobeObserved

1669.9

556.9

987.9

752.0

1113.3

1661.0 1228.8

1919.4

1893.7 1602.2

1716.8

1153.1

1162.9

448.0

1097.4

2774.0

4512.4

2196.3

2640.5

2264.1

3807.3

3977.0

4468.6

3331.5

2365.9 2074.4

2391.6

2164.1

2968.7

183.3

WaterintheInterstellarMedium:inabsorption:Lowestortho-

andpara- transitionsinemission(shocks;outflows)

Lowesttransitions+excitedlinesnear1100GHz

WaterinDenseCores:Probablylowesttransitionsonlywillbedetectable

WaterinDisks: Arangeoftransitionsispossible

WaterintheSolarSystem:Lowestortho– andpara- transitions;isotopologuesessential

WaterTransitionstobeObserved

DetailsdependonbandwidthofreceiverswhichwillbeSISmixers

Frequency-multipliedlocaloscillatorsourceshaveadvancedsignificantlyandshouldnotbeaproblem

Injectlocaloscillatoreitherthroughwaveguidedirectionalcoupleroremploybalancedmixers

Somereceiverscancovermorethanonelinewithmultiplesecondlocaloscillators

Transitions of H2OFreq (GHz) Transition Species509.3 110 – 101 (HDO)547.7 110 – 101 (o-18)552.0 110 – 101 (o-17)556.9 110 – 101 (o-16)987.9 202 – 111 (p-16)994.7 202 – 111 (p-18)

1107.2 111 – 000 (p-17)1009.9 211 – 101 (HDO)1113.3 111 – 000 (p-16)1097.4 312 – 303 (o-16)1153.1 312 – 221 (o-16)

ReceiverConceptstoIncreaseSensitivity

FSS#FSS#

Band#3#Array#Band#2#Array#

Band#1#Array#

Ellipsoidal#Mirror#

Ellipsoidal#Reflector#

Polarizing#Grid#Beam%from%telescope%(through#calibraBon#system)#

Orthogonal#PolarizaBon#Directed#to##2nd#Receiver##

1. UseDichroicFilters(FrequencySelectiveSurfaces)andoperateallchannelssimultaneously

2. Employanarray(sizedependsonbudget,cooling,andpower)forimagingISMandCores

3. Beamswitchbetweentwopixelsforobservationofsmallsources(internalmirror)

4. Dualpolarizationreceiversforallfrequencies

5. Improvedmaterialsfor1THzSISjunctions

6. Cooledwithclosed-cyclerefrigeratortoget5yrlifetime

SpectrometerforHeterodyneReceiversThishasbeenanissueatmm/submmwavelengthsbecauseofrequiredlargebandwidthandmultiplicityoflines

Solutionshaveincludedfilterbanks (typicallyusedonatmosphericsounders),chirpspectrometers(lowpower;usedonplanetarymissions),andacousto-opticalspectrometers(complex,heavy;usedonSWAS(SMEX)andHerschel/HIFI)Digitalsignalprocessing,offeringmanyadvantages,isnowfeasiblebutFPGAapproachisrelativelypowerhungry(~4W/GHzBW)IdealtechnologyiscustomVLSIusingtechnologydevelopedforcellphonesandothercommunicationssystemsDr.AdrianTangatJPLhasuniquepartnershipwithUCLAteamandQualcommfordevelopmentofCMOSVLSIchipsforspaceapplications

“SPECTROCHIPII”has750MHzbandwidth,512spectralchannels,includesdigitizer,dataaccumulator,andUSBoutputinterface5x10cmsizeonboardwithsupportcircuitry;200mWDCpower

Thenextgenerationwillhave3GHzbandwidth,8KchannelsThelowpowerandmasswillallowsimultaneousoperationofmultiplereceivers

Spectrochip II

v A Full 1.5 GS/s spectrum analyzer chip in advanced 65nm CMOS was developed by UCLA’s high speed electronics lab.

v Integrated 7b digitizers, offset and interleaving calibration functions, clock management system and vector accumulation.

v 256dsb/512ssb channel quadrature output with integrated USB 2.0 controller

Full SoC Die Photo Full SoC Block Diagram

Module Assembly

IncreasedSensitivity(wrt Herschel)RequiresaLargerTelescope

• Increasesampleofcomets:5/yearminimumtoget15-25in3to5yearmissionwilldramaticallyimprovestatisticsandcoverageofdifferenttypesThisrequires2-4xhighersensitivity;cometemission&missionmodelingrequired• Increasedsensitivitytostudywaterisotopologues inabsorption;signalproportionaltocollectingarea• Greatersensitivityessentialtomakestudyofwaterindisksbeyondthenearestfewpossible• Improvedangularresolutiontoimagevelocityfieldthroughoutcoresincludingmoredistanthigh-masscores(Herschelhad40”FWHMat557GHz)

WaterProbeMissionTelescopeNarrowlinewidthsrequirehighresolution(<0.25km/s;R>106)TheonlyviableapproachisheterodynereceiversTheemissivityofopticsat250μm islowenough(andreceivernoisehighenough)thatTELESCOPETEMPERATUREISUNIMPORTANTTelescopeandmissiondesignrequirereasonablethermalstabilitytomaintainsurfaceandpointingaccuracy(𝝈 <15μm)L2isagoodlocationfromtheseviewpoints.Passiveradiationwilllikelybringtelescopeto~100K(needsfurtherstudy)WillneedlargesunshieldObservingmodesimilartoHerschel:targetsin40o wideconehavingaxisalongspacecraft-sundirectionbetweenobservable

WaterProbeTelescope6-7mdia.DeployableCassegrainReflectorfitsinshroudofFalcon9Heavy

Thisversionemploys36~1mhexagonalpanels

Originalengineeringstudyemployedan“optical”f/Dratiowithverylongsecondarysupportstruts

Relatively“JWST-like”

Limitingminimumwavelengthto250µmmeansthataccuracyrequirementis100xlessdemanding

PossiblematerialsincludeSiC(asHerschel)butcouldalsobemadeofcarbonfibercore+aluminumskins

ThankstoOttoPolancoforgraphics

DeployableQuasi-MonolithicTelescopeStructure

10mx12msingle-layersunshadewithsolarpanelsonlowerside

WaterProbeMission

• Proposalsubmittedon15NovembertoNASA• 15-monthstudyproposedincludingTeam-XstudyatJPL• Opentocommunity;twoworkshopstodefineinstrumentandmission• Selectionbasedonscientificinterestandplausibilityof<$1Btotalcost• Selection– sometimeinSpring2017