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DORISUSOBehaviorRevealedbyJason-2/T2L2F.G.Lemoine,P.Exer)er,A.Belli,N.Zelensky
IERSUnifiedAnalysisWorkshopUniversitéParis-Diderot
Paris,FRANCEJuly10-12,2017
2\1
DORISSystemDescripAon
DORISSatelliteAntenna
DORISOven-controlledUSO
DORISSystemConfiguraAon
AuriolandTourain,Adv.SpaceRes.,(2010)
USOCharacterisAcs:•HeartofDORISsystemisUSO.•AccuracyofphasemeasurementsdeterminedbystabilityofUSO.•USOisacrystal-oscillatorthatispre-hardenedtoreducesensiAvitytoradiaAon(e.g.Jason-2,Jason-3).•DORISUSO’shaveasensiAvitytoradiaAonexposurethroughpassageintheSouthAtlanAcAnomaly.Jasonsatellitesmoreaffected@1336km);Discernibleonothersatellites(SPOT-5,@~800km).
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DORIS/USO–PreviousExperiences
SPOT-5FreqDri_from2011,Hz/day
Willisetal,CRGeoscience.(2004)
1.Anomalousfrequency(Δf/f)leadstoanomalousheightesAmaAonforstaAonsinheartofSAA.2.ForstaAonsonborder,behavioriscomplicatedbecauseascendingordescendingpassesaremoreaffected.3.AcorrecAonmodel(JMLemoine&Capdeville,2006)allowsdatatobeusedforPOD.Notsuitableforpos-vel.esAmaAon(SAAstaAons).
DORISTOPEXvs.Jason-1FrequencyAnomalies,Apr.2003
Stepaneketal.Adv.SpaceRes.(2013)
1.SPOT-5SAAeffectundetectedunAlpointedoutbyStepaneketal.(2010).2.SmallerthanJason-1,butsAllnoAceableeffect;Importanta_er2006.3.StaAonsinandnearSAAaremostperturbed;e.g.CADB,ARFB,SANB,KRWB,HEMB,ASEB.4.CorrecAvemodelusedforITRF2014.Capdevilleetal.(2016).
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RadiaAonExposure(fromCNESEngineeringtables)
Jason-2,3:~2500rads/yr
SPOT-4,5,SARAL,ENVISAT:~360rads/yr
ImpactonDORIS/ITRF2014
SAAOn-boardFreqsignalover5-days,Jason-1,SPOT-5,SPOT-4
Capdevilleetal.Adv.SpaceRes.(2016)
1. ITRF2008staAonposiAons&velociAesfor“SAA”staAonsdirectlyaffectedbyuncorrectedSPOT-5data.
2. ForITRF2014:AllACsusedcorrecAvemodeland/ordownweighAngeliminaAonofSAAstaAondataforSPOT-5&Jason-1.
SatellitedatausedinITRF2008/ITRF2014
Moreauxetal.Adv.SpaceRes.(2016)
Jason-1:Onlyincludedata11/2004-07/2008
SPOT5:Usecorrecteddata,2006-2015
1. Jason-1includedsinceitsinclinaAoncomplementstheothersatellites.
2. Use“correcteddata”+downwt/eliminateSAAstaAons.
3. NoothersatelliteUSOsreceivespecialtreatmentinITRF2014.
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Jason-2/T2L2
ExerAeretal.Adv.SpaceRes.(2010)
1. “TimeTransferbyLaserLink”2. Twophotondetectors+eventAmer
withpsresoluAonlinkedtotheDORISUSO.
T2L2recordsinAmescaleprovidedbyDORISthearrivalAmeoflaserpulsesatJason-2.IncombinaAonwithprecisegroundclocksatSLRstaAons(H2masers),itispossibletodetermineΔf/foverAmeintervalsofT=60secs.PrecisionisdependentonshorttermstabilityofUSO,quanAty&qualityofrangemeasurements.3-5x10-13
Jason-2
LaserRetroreflectorArray
Jaylesetal.Adv.SpaceRes.(2016)
TwoApplicaAons:(1)“Synchronize”TimingofSLRnetwork.(2)StudyindetailbehaviorofUSOinspaceenvironmentandcharacterizedifferenteffects(radiaAon,thermaleffects,aging).
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T2L2Data:Example
Bellietal.Adv.SpaceRes.(2016)
1. BestdatacomesfromstaAonswithH2masers:Grasse(7845),Herstmonceux(7840).
2. DatacanreadvariaAonscausedbyradiaAondosage(SAA),temperaturevariaAons,andaging.
3. Thedatabenefittwotechniques:bothDORIS&SLRgivingusanunderstandingandglobalperspecAve.
Δf/finJan.2013fromfiveSLRstaAons.
SeealsoA.Belli,PhDThesis(2017)
USOEffects&ModelDerivaAon
Bellietal.Adv.SpaceRes.(2016)
SeealsoA.Belli,PhDThesis(2017)
TemperatureEffectsonJason-2USOJan.2013,showingorbit-to-orbiteffects&impactofchangeinJason-2aqtude.
Jason-2CARMEN87MeVintegratedprotonfluxmap(2009–2011average).
Capdevilleetal.Adv.SpaceRes.(2016)
RadiaAonModel
Dri_Model
Jason-2USOModel&Comparisonw.T2L2
Bellietal.Adv.SpaceRes.(2016)
RadiaAonModelover~1.5-daysforJason-2showingeffectsofSAApassage.
Bellietal.Adv.SpaceRes.(2016),Fig4
Jason-2FrequencyvariaAonsfromTemperatureandRadiaAon:ModelvsT2L2data.
USOEffects&ModelRefinementforJason-2&Jason-3
TemperatureEffects •Sufficienttocalculateonlyrateterm:
α1[T(t)–To]•CoefficientsforJ2(2008),J3(2016)similarmagnitudebutoppositesign.
RadiaAonEffect@60-days
•A60-daysignalwasobservedintheT2L2datawhenthes/cisinfixedyaw.Increaseovertendays,thenrelaxaAonover45-50days.•Bellietal.(2017)proposethisisduetoalignmentofYaxisofs/cwithmagneAcfieldlines,leadingtoincreasedsensiAvitytoradiaAoninSAAareainfixed-yawregime.•Itispossibletosolveexplicitlyforcoefficientstomodelthisbehavior.•ThesignificanceisthatBellietal.(2017)haveidenAfiedanaddiAonalsignalataJason-sub-draconiAcperiod(~60days)thatisinthecurrentdata,andisnotdrivenbyradiaAonpressuremismodeling.***
Bellietal.,EuropeanFrequency&TimeForum(2017)proceedingpaper
***AC’smustsAllimproveSRPmodel,includemoAonofsolararraysusingquaternions.
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Data used: MOE SLR stations (T2L2) Temperature of the box => df/f0 with 1.85 10-12 /degree
CNES POD (MOE) can “read” USO for H2 maser (time, frequency) beacons ‒ since freq. biases (range-rate) biases estimated per pass. Sees freq. variations with precision of ~1-1.2 x 10-12
compared to ~3 x 10-13 for T2L2
Jason-2USOBehaviorvs.CNESMOEFreq.biases
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DORIS USO (frequency bias): long term
Frequency variations of J3 are >> J2 in 2016 but not in 2008
RelaAvefrequencyvariaAons2015-2016Jason-2freqvariaAons2008vs2016RadiaAonsensiAvityhasdecreasedwithAme.
13Bellietal.IDSWorkshop(2016)
Here,MOEΔf/farefilteredwith1-dayfiltertoeliminatemedium&long-termsignalJason-2Δf/f(2008)(TOP)vsJason-3Δf/f(2016)(BOTTOM)fromMOEsoluZons.Jason-3sensiAvitytoradiaAonisabout~3XthatofJason-2atthesameageofspaceexposure.
Jason-2 vs Jason-3 Sensitivity
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Summary
DORISUSOSensiAvitySummary1. USOsshowsensiAvitytotemperature,radiaAon,andhaveagingeffects.2. A“60-day”effectonDORIS-USOisidenAfiedthatisrelatedtoJasonaqtude
lawandanisotropyofincidentradiaAonfluxintotheUSObox.3. SensiAvityisaffectedby“pre-treatment”andamountofshieldingons/c.4. Ageneralmodelthataccountsparametricallyfortheseeffectscanbe
derivedforJason-2andeventuallyforJason-3.5. Lowersatellites(SPOT-5)notimmune.Suggeststhereisaneedforgeneral
treatmentoftheseeffectsonallDORISsatellites.
ImmediateFutureAcAons1. PIerreExerAer/A.BellitomakeavailablecorrectedDORIS/V2Data(Jason-2)
fortesAngbytheDORISAnalysisCenters.2. ImprovedFrequencymodelofJason-2&Jason-3canbeimplementedin
DORIS/RINEXprocessing–tobetestedbyNASAGSFCandotherDORISACs.