a probe mission to trace water from interstellar clouds to ... · tracing water from interstellar...
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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