战术小卫星TacSat3 ARTEMIS高分辨率的超光谱成像仪.docx

战术小卫星TacSat3 ARTEMIS高分辨率的超光谱成像仪.docx

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战术小卫星TacSat3ARTEMIS高分辨率的超光谱成像仪

（网络查询关键词）

PreflightandVicariousCalibrationofArtemis

ARTEMISHyperspectralSensor

AchievingMultipurposeSpaceImagingwiththeARTEMISReconfigurablePayloadProcessor

TheARTEMIS,ahyperspectralimagingsensorfromRaytheon,isbeingtaskedfortheAirForceSpaceCommand’stacticalmilitaryrole,whichisthefirstofitskind.

RaytheonARTEMISHyperspectralImagingSensorforTacticalMilitaryRole

Isthereabesthyperspectraldetectionalgorithm?

（SPIE）

InfraredTechnologyandApplicationsXXXVI（ProceedingsVolume）

IEEEARTEMISHyperspectralSensor

HyperspectralSensorARTEMIS

ARTEMISHyperspectralPayload

TacSat3ARTEMIS

TACSAT3-Information

|Home |Passes（visible） |Passes（all） |Orbit |

Identification

USSPACECOMCatalogNo.:

35001

InternationalDesignationCode:

2009-028-A

SatelliteDetails

Orbit:

416x446km,40.5°

Country/Org.ofOrigin:

USA

Intrinsicbrightness（Mag）:

5.2（at1000kmdistance,50%illuminated）

Maximumbrightness（Mag）:

1.4（atperigee,100%illuminated）

Launch

Date（UTC）:

May18,2009

Sensorcomplement:

（ARTEMIS,ODTML,SAE）

BuildingontheexperienceswithTacSat-1and-2,TacSat-3isthefirstspacecraftoftheseriestohavegonethroughaformalpayloadselectionprocesswithAFSPC（AirForceSpaceCommand））andCoordinatingCommands（COCOMs）andServices.

ARTEMIS（AdvancedResponsiveTacticallyEffectiveMilitaryImagingSpectrometer）:

ARTEMISisahyperspectralimager（HSI）,fundedbyAFRLwithadditionalfundingbytheUSArmy,designedanddevelopedatRaytheonSpaceandAirborneSystemsofElSegundo,CA,usingCOTScomponentsextensively（ARTEMIScontractawardin2005）.ThereisalsoacollaborationontheimagingspectrometerfromNASA/JPL.Themainobjectivesare:

•Todemonstratetacticallysignificanthyperspectralimagerycollectionandprocessingsufficienttomeetmilitarilyrelevantdetectionthresholds

•Forasingle-passopportunity,thetimeperiodfromaspecifiedtargetcollecttodeliveryofaprocessedproducttothewarfighterlevelmustoccurwithin10minutes（threshold:

30min）.

Theinstrumentconsistsofatelescope,animagingspectrometer,ahighresolutionimagerandareal-timeprocessorreferredtoasHSIP（HyperspectralImagingProcessor）.ARTEMISprovidesHSIobservationsinthevisibleandSWIR（ShortWaveInfrared）regionaswellaspanchromaticdata.Thespectralrangecoverageisfrom0.4-2.5µm.

ThetelescopeisastandardRitchey-Chrétienformandistelecentricasisrequiredtomeetthespectralandspatialuniformitygoalsoftheimagingspectrometer（heritageofTacSat-2）.Additionallythesecondarymirrorhasabuilt-infocusmechanismforon-orbitoptimization.12）13）14）15）16）

Figure6:

IllustrationoftheARTEMIStelescope（imagecredit:

AFRL）

TheimagingspectrometerisofthebasicOffnerformconsistingoftwopoweredreflectingsurfacescomprisingtheprimaryandtertiaryelements.Thesecondarymirrorisreplacedbyacurvedgratingfordispersionandisthelimitingstopofthesystem.Thisformhasthemeritofbeingsimple,compact,andbothspatiallyandspectrallyuniform.Spatialandspectraluniformityiscriticaltotheoperationalperformanceofimagingspectrometersasitenablesrobustexploitationofdataproducts.Spectralsamplingisat5nmintervals.Additionallythedesignhas<5%spatialandspectralnon-uniformity.Theslitisreticulatedwithsmallaperturesatthetopandbottomtoaidinalignmentandtesting.

Thedual-angleblazegratingwasselectedlargelyduetoitssuperiorperformanceinreducingtheeffectofobscurationsatthegratingstop.ThegratingisdesignedtooptimizetheSNR（Signal-to-NoiseRatio）.

Figure7:

SchematicelementsoftheOffnerspectrometer（imagecredit:

AFRL）

Theimagingspectrometerdesignalsoreliesuponasinglesubstrate-removedHgCdTefocalplanearray（FPA）thatextendsitssensitivityintothebluewavelengthstocoverthefullspectralrange（VNIRandSWIR）.Thissinglefocalplaneeliminatestheco-registrationissuesassociatedwithmulti-FPAsystems.ThequantumefficiencyoftheFPAisbetterthan70%atallwavelengthsandthearrayisequippedwithathree-zoneblockingfilterforordersorting.Asignificantrequirementforgeolocationaccuracyacrossthefullspectrumofeachspatialpixelisspectralco-alignment.

Thehighresolutionimagerisadaptedfromoff-the-shelfhardwareforsimplicityandcostsavings.ItconsistsofamodifiedDalsaPiranha2linescanCCDcamera.Themodelselectedhas4096pixels（7µmsquarepixels）,dualoutput,1kHzframerate,anda10bitdigitization.Thecamerahasbeenmodifiedtosurvivethespaceenvironment.

Spectralrange

0.4-2.5µm（coverageofVNIRandSWIRrange）

Panimagery

inthevisibleregiononly

HSIdata

intheVNIRandSWIRregion

Spectralsampling

5nmbands

Telescope

StandardRitchey-Chrétienformandistelecentric

Imagingspectrometer

BasicOffnerformconsistingoftwopoweredreflectingsurfacescomprisingtheprimaryandtertiaryelements

FPA（FocalPlaneArray）

AsingleFPAisusedtoeliminateco-registration

Detector

HgCdTe

HSIP

OnboardDSP（DigitalSignalProcessor）toprocesstheimagecube,16GBstorage,reprogrammable,real-rimetargetcueing

Instrumentmass

170kg

Table1:

SomeparametersoftheARTEMISinstrumentation

Note:

Themilitarynatureoftheprogramdoesnotrevealanyspecificsastotheperformanceparametersofthehyperspectralimager-suchasresolutions,swathwidths,etc.

ARTEMIScalibration:

Thespectralimageryacquiredwillmakeuseofsolarradiation-basedcalibrationmethodsforboththepre-flightandon-orbitradiometricandspectralcalibration.Thepre-flightcalibrationreliesonauniqueexperimentinwhichARTEMISviewedtwopanelsilluminatedbythesun.Thefirstpanelwasspecially-coatedtoprovideasetofknownabsorptionfeaturesforthespectralcalibrationofARTEMIS.AsecondpanelwithrelativelyflatspectralreflectanceandmeasuredreflectancecharacteristicswasusedfortheabsoluteradiometriccalibrationofARTEMIS..17）

At-apertureradiancefromthepanelwhileilluminatedbythesunwasdeterminedthroughdirectmeasurementusingawellcalibratedtransferradiometer.Themultispectralmeasurementsfromtheradiometerwereconvertedtohyperspectraldataviameasurementsfromafield-portablespectrometer.Asecondarypredictionofat-apertureradiancewasalsoprovidedthroughaSRBC（SolarRadiation-basedCalibration）.TheSRBCapproachreliesonthedeterminationofthespectralsolarirradianceincidentonthepanelcombinedwiththeknownBRDF（Bi-directionalReflectanceDistributionFunction）togivethereflectedspectralradiance.Thesolarirradianceisfoundbytransmittingagivensolarirradiancemodelthroughtheatmosphereusingatmospherictransmittanceasafunctionofwavelengthfoundfromsolarradiometermeasurements.

Acorrectionforskylightilluminationonthepanelisobtainedfrommeasurementsofthepanelwhileshadedfromthesun.ErroranalysisofthespectralcharacterizationshowsthecenterwavelengthofARTEMISbandscanbedeterminedtobetterthan1nm.Theabsoluteuncertaintyofthesolar-basedradiometriccalibrationislessthan3%inspectralregionsnotaffectedbystrongabsorption.

ARTEMISmakesuseofanonboardhealthmonitortoevaluateshort-termchangesinradiometricresponseofthesensorbutwillrelyonvicariousmethodsforthelong-termevaluationofthesensor’sabsoluteradiometricresponse.Theon-orbitvicariousradiometriccalibrationwillbecarriedoutusingthereflectance-basedmethod.Thisapproachreliesonmeasurementsofsurfacereflectanceofselectedgroundsitesandatmosphericopticalpropertiesthatareusedasinputtoaradiativetransfercode.Themeasurementsandradiativetransfercodeprovideresultsat1nmspectralintervalsfortheentirespectralrangeofARTEMIS.

Figure8:

Artist'sviewoftheTacSat-3spacecrafttakinghyperspectralimagery-i.e.an“imagecube”（imagecredit:

AFRL）

Demonstration/experimentationwithtacticaltaskinganddownlinkofHSIdata:

TheARTEMISinstrumentationincludesaco-alignedpanchromatichighresolutionimager（HRI）andanonboardprocessor,referredtoasHSIP（HyperspectralImagerProcessor）orsimplyasARTEMISprocessor.TheArtimisprocessoruniquelyseparatespayloaddatamanagementsuchasstorage,processing,andcontrolseparatefromanintegratedsensorandprocessor.ThisallowsfortheARTEMISandSensorProcessorcombinationtobehostedonamoregenericplatformsuchasamodularbusbyadaptingonlyapiece（theSP）asrequiredforfutureconcepts.

Themodular,scalableprocessorarchitecturehasbeendesignedanddeveloped（bySEAKREngineeringInc.）toenablehighperformancereconfigurableprocessingforspaceapplications.HSIPisprovidingreal-timehyperspectralimageprocessing,imagestorage,payloadcontrolandpowerswitching,andflexibleplug-and-playinterfacessuchasSPAs.18）19）20）21）

Thiscombinationwillenablethetacticalusertorequestahyperspectralanalysisofagivenregionforspecificobjects.Theimagerwillcollectthefullhyperspectraldatacubeoftheregionplusapanchromaticimageofthearea.Theon-boardprocessorwillanalyzetheregionforobjectsofinterestandwillthengeo-rectifythelocationoftheseobjectswiththepanchromaticimage.Thetacticaluserwillthenbeprovidedwithapanchromaticimageoftheregionwithiconsontheimagethatrepresentlocationsoftheobjectsofinterest.

ARTEMISprocessor:

TheinterfacesbetweencomponentswithintheARTEMISprocessorincludepowerplane,cPCI（CompactPeripheralComponentInterconnect）