Radiometric Balloon-Flight Results from the HySICS · 2017-04-11 · CLARREO SDT Meeting Hampton, VA, 29 Nov. 2016 HySICS Results Greg Kopp -p. 3 PI:Greg Kopp / LASP CoIs:Co-I –Peter

CLARREOSDTMeetingHampton,VA,29Nov.2016 GregKopp- p.1HySICSResults

RadiometricBalloon-FlightResultsfromtheHySICS

CLARREOScienceDefinitionTeamMeeting

GregKopp,P.Smith,C.Belting,Z.Castleman,G.Drake,J.Espejo,K.Heuerman

LaboratoryforAtmosphericandSpacePhysics,Univ.ofColorado,Boulder,CO

HyperSpectralImagerforClimateScience

Flights: Sept. 29, 2013 and 18 Aug. 2014Observations: 8 hours at float

Principal Investigator: Greg Kopp

HySICS is an instrument intended to acquire extremely accurate radiometric images of the Earth relative to incident sunlight

Questionstobeanswered:

Climatedatabenchmarktechnique

demonstration

HySICSisaballoonpayloadthatismounted

ontheWallopsArcSecondPointer(WASP)

flyingoutofFt.Sumner,NM

Ratio ofsolarincomingtooutgoing

radiancesbenchmarksclimate

withoutrelianceonaccuracy

PI: Greg Kopp / LASP

CoIs: Co-I – Peter Pilewskie / LASPBalloon Flight Manager – David Stuchlik / WFF

Build and flight test a hyperspectral imager with improved radiometric accuracies for climate science• 350-2300 nm with single FPA to reduce cost & mass• <0.2% (k=1) radiometric accuracy• <8 nm spectral resolution• 0.5 km (from LEO) IFOV and >100 km FOV• <0.13% (k=1) instrumental polarization sensitivity

Perform two high-altitude balloon flights to demonstrate solar cross-calibration approach and to acquire sample Earth and lunar radiances

Single HgCdTe FPA covers full shortwave spectral range with reduced mass, cost, volume, and complexity

Incorporate solar cross-calibration approaches demonstrated on prior IIP to provide on-orbit radiometric accuracy and stability tracking

Orthogonal configuration reduces polarization sensitivityNo-cost balloon flights from experienced team at NASA

WFF demonstrate on-orbit capabilities

Objective

Approach

HySICS to demonstrate climate science radiometric accuracies in shortwave spectral region

HyperSpectralImagerforClimateScience

LunarReconstruction

GroundReconstruction

SolarDataCube

Aperture(s)

Mirror

Grating

VacuumWindow

andOrderSorting

FilterFilter(s)

HySICSInstrumentOptics

ItemsGuidingDesign:

• Highaltitudeballoonflightenvironment

• Pushbroom imagingspectrometer

• Precisionaperturestopinfrontofthe

telescope

• FPAoperatesat150K

• Lowpolarizationsensitivity

Parameter Design Requirement

SpatialResolution 2.5arcmin

FieldofView(crosstrack) 10°

IFOV 0.02°

WavelengthRange 350-2300nm

WavelengthResolution 6nm, constant,Nyquist

Aperture 0.5,10,20mmdiameter

Aperture(s)

Mirror

Grating

VacuumWindow

andOrderSorting

FilterFilter(s)

RadiometricEfficiencyCalibratedOn-Orbit

ImproveRadiometricAccuraciesinVisible/NIR

• Currentinstrumentshave

>2%radiometricaccuracy

– Accuracyandstabilityrelyon

groundcalibrations,on-board

lamps,cross-calibrations,solar

diffusers,orlunarobservations

SolarCross-CalibrationsRequire~10-5 Attenuation

AttenuationMethodsUtilizedbyHySICS

• Apertureattenuation – Reductionof

inputlight-collectingarea

– Canachieveattenuations~10-3

– Limitedbydiffraction

• Integration-timeattenuation –

Reductionoflight-collectingtime

– Canachieveattenuations~10-3

– Limitedbylinearity

• Filterattenuation – spectralfilters

calibratedwithon-orbitlunarviews

– Canachieveattenuations10-1

– LimitedbyS/N

Allattenuationmethodsarerelativemeasurements;directmeasurementsofsolarorEarthirradiancesnotrequired.

EarthViewing SolarViewing

Hyper-

spectral

Imager

Hyper-

spectral

Imager

InputAperture

Filter

Exposuretime

Integration

ScienceandCalibrationObservations

• GroundObservation

– Acquirehyperspectraldatafromgroundscenes

• SolarIrradianceMeasurement(Cross-Slit

– Measurespectralsolarirradiancebyintegrating

imagesaftercross-slitscanofsolardisk

• Flat-FieldCalibration(Along-SlitScan)

– Scanslitsmoothlyalongdiameterofsolardisk

– Requirespointingaccuracyof~15arcsec

• CalibrationsusingMoon

– Filters:PlaceslitacrossMoonandacquire

measurementswithandwithoutfilters

– Flat-field:along-slitscanusinglargeaperture

• Drivesyetmorestringentpointingrequirements

Observationsnotpossiblethroughvariableatmosphere,soneed>30,000maltitude

Cross-SlitScan Along-SlitScan

FilterCalibration

GroundObservation

AttenuationCalibrations – Apertures

• NIST-calibratedareasprovide

uncertainties<320ppm

Hyper-

spectral

Imager

20mmdiameter 0.5mmdiameter

Actualsystemapertures

Aperture Diameter (mm)

Aperture Area (mm2)

Area Uncertainty (ppm) (k=1)

19.9862 313.72454 180.51542 0.20865 317

Butthere’salotmoretoit...

AttenuationCalibrations – Filters

• Intendedattenuationsof10-0.9

• Lunaron-orbitrelativecalibration

– Successionoffilterin/filteroutradiance

measurements

– Trackpossibledegradation

– Lowlightlevel(comparedtosolar

irradiance)limitsattenuationsto~10-1

• Absorptiveglassfiltersspanspectrum

– Bulkeffectismorestablethanthinfilm

– Lowerreflectedlight

– Simplerdependenceonangleofincidence

Hyper-

spectral

Imager

InputAperture

Filter

LunarFilterCalibration

AttenuationCalibrations – IntegrationTime

• FPAsystemnon-linearity

– Non-linearitiesarecharacterized

forattenuationsof10-3

• FPEnon-linearity

– 1ppmoverattenuationsof10-3.3

FullImageLinearityCorrectionUncertainty

LinearityResidualofPixel(100,100)

FPAlinearitygreatlyexceeded

expectations

Obviatesneedforfilters

>103 range

HySICSIntegratedandReadyforLaunch

BalloonInflation

HySICSLaunch

putshortHySICSLaunchvideohere

HySICSFlight#2Summary• FLIGHTNO.: 650N

• LAUNCHDATE/TIME: August18,2014,15:36Z

• LAUNCHSITE: FortSumner,NM

• BALLOONVOLUME: 0.8MCM(29.47MCF)

• BALLOONWEIGHT: 1,675KGS(3,693LBS)

• EXPERIMENTWEIGHT: 1,925KGS(4,244LBS)

• SUSPENDEDWEIGHT: 2,722KGS(6,000LBS)

• GROSSINFLATION: 4,836KGS(10,662LBS)

• FLOATALTITUDE: 37.19KM(122KFT)

• BALLOONTHICKNESS: 20.32MICRONS(0.80MIL)

• SERIALNO.: 90/CSBFNO.1205

• DISCIPLINE: WU/SolarandHeliospheric

• TOTALFLIGHTTIME: 8hrs,54min

FloatAltitude

Declared

• Launch@09:35on18Aug.2014

• Ascenttime:2hours,17minutes

• Floataltitudeof122,000feet@11:52

HySICSFlight#2Path

HySICSImagesfromFlight#1

• Flight#1(EngineeringFlight)demonstratedspatial/spectral

scanningcapabilityofallthreetargetsLunarReconstruction GroundReconstruction SolarDataCube

GroundScanandDataCubefromFlight#1

Groundscan(13:25:30)

R=653nm,G=535nm,B=457nm

HySICSGroundScansfromFlight#2• EachFlight#2groundscanacquiredin~5min.from4200images

EarthLimbScansAcquiredfromHySICS

LunarDataCubefromHySICSFlight#2

HySICSCross-CalibrationFormalismSpatial/spectralground-images,Smeas_obj(l)[DNs],areconvertedtophysicalspectral-irradianceunits[W m-2 nm-1]byanon-orbit-

determinedunit-conversionfactor,C(l)[W m-2 nm-1 DN-1],andthe

radiance-attenuationfactor,A(l)[unitless],whichcorrectsfortheoptical-throughputandintegration-timesusedforsolar- vs.Earth-

viewing

whereSSI(l)representstheradianceoftheobservedsceneinSI-traceable,physicalunits andC(l)istheunit-conversionfactor

withSSI(l)beingtheSSI(providedbyanindependentspace-flightinstrumentorasolarmodel)andSmeas_Sun(l)theHySICS’sin-flightmeasurementoftheSSIinDNsacquiredbyspatially-integrated

cross-slitscansofthesolardisk.

SSI(l) = Smeas_obj(l) A(l) C(l)

C(l) = SSI(l) / Smeas_Sun(l)

HySICSCross-CalibrationFormalismBeingameasurementofratiosacquiredoverashortperiodoftime,

theHySICSsolarcross-calibrationapproachdoesnotrelyonintrinsic

calibrationaccuraciesorlong-termstability

Allfollowinguncertaintiesarek=1unlessotherwisenoted

SSI(l) = SSI(l) · Smeas_obj(l) / Smeas_Sun(l) · A(l)

FPACorrections&Uncertainties• Bad-Pixelremoval

• ReadNoise:determinedforeachpixel;8.3DNaverage

• DarkSignal:0.29DNforlongestintegrationtimes(negligible)

• ThermalBackground:scene- andtemperature-dependent

– Canalsocontributetoshotnoise

• Linearity:~0.30%�0.12%

• Gain:determinedforeachpixel;12.01�0.12e-/DNaverage

– <0.003%ofa15%full-scalesignal

• Flat-Field:Acquiredon-orbitbysolarandlunarscans

Severaluncertaintiescanbereducedbymultiple-imageorrepeated-scanobservationsofsource(ifstatic)

ApplicabletoSunandMoonbutnotgroundobservations

Instrument-LevelUncertainties• ShotNoise:signal-dependent;dominantsourceofuncertainties

forgroundscenesacrossmuchofspectrum

• Diffraction&Scatter:measuredandmodeled;affectssolar

observationsatlongwavelengths

– UsingNIST-quoted10%uncertainties

• SpectralScale:Determinedon-orbit;scaleswithspectralgradient

– Rarelyadominantcontributortonetuncertainties(exc.solarinUV)

• BrightnessOffset:Often2nd largestuncertaintyforgroundscenes

• Polarization:Causedbygratingsensitivity

– Affectsradiometryofpolarizedscenes

Severaluncertaintiescanbereducedbymultiple-imageorrepeated-scanobservationsofsource(ifstatic)

ApplicabletoSunandMoonbutnotgroundobservations

MeasurementUncertainties

SSI(l) = SSI(l) · Smeas_obj(l) / Smeas_Sun(l) · A(l)

seeKoppetal.2017forfinaluncertainties

solarground aperture

AttenuationUncertainties – IntegrationTimeMethodprovidesgreaterattenuation

rangewithloweruncertaintiesthan

anticipated,contributinglittleto

attenuationuncertaintiesIntegration-TimeAttenuation-MethodUncertaintiesUncertaintyParameter BrightScene

(53%FS)[%]Max.Int.

(75%FS)[%]ElectronicLinearity 0.00016 0.00016GainNon-linearity 0.050 0.120Total 0.050 0.120

>103 range

Typicalbright

groundlevel

AttenuationUncertainties – FilterRatio(Sun)• Filtercalibrationuncertainties0.04%- 0.1%from1000- 2300nm

– Dominatedbyread- andshot-noise,especiallyintheUV/Visibleregion

FilterRatioUncertainty:NG4#2 FilterRatioUncertainty:NG5#2 FilterRatioUncertainty:BG25

Filter-CalibrationAttenuation-MethodUncertaintiesParameter MeasurementUncertainty(%) MeasurementUncertainty(%) MeasurementUncertainty(%)

550nm 1000nm 2000nm 550nm 1000nm 2000nm 550nm 1000nm 2000nmFilter(SolarCalibration) NG4#2 NG5#2 BG25ShotNoise 0.94 0.1 0.047 0.25 0.065 0.035 NA 0.027 0.018ReadNoise 0.97 0.097 0.048 0.25 0.06 0.035 NA 0.015 0.011WavelengthBinLocation 0.027 0.015 0.009 0.027 0.015 0.009 0.027 0.015 0.009Filter-outUncertainty 0.35 0.049 0.064 0.35 0.049 0.064 0.35 0.049 0.064BackgroundLevelCorrection 0.23 0.023 0.011 0.082 0.02 0.011 NA 0.005 0.003BlackbodyRadiationCorrection 0.0001 0 0 0 0 0 NA 0 0DarkImageReadNoise 0.069 0.007 0.003 0.018 0.004 0.002 NA 0.001 0.0008DarkImageShotNoise 0.003 0.0003 0.0001 0.0007 0.0002 0 NA 0 0Total 1.416 0.150 0.094 0.505 0.104 0.082 NA 0.060 0.068

• Filtercalibrationsandflat-fieldingfromMoonoflimitedsuccess

– Limitedbythelowlunarsignalfromthenarrowlunarcrescentandpointing

sensitivity

– Lunarfilterratiouncertainty1%- 2%from600- 2300nm

LunarCalibrationsLimitedatTimeofFlight

LunarPhase>90°

29/4/16, 3:48 PMGrapeEnvy Moon Phase Calendar

of 1https://stardate.org/cgi-bin/mooncal/mooncal.cgi

Aug 2014

Sun Mon Tue Wed Thu Fri Sat

3 4 5 6 7 8 9

10 11 12 13 14 15 16

17 18 19 20 21 22 23

24 25 26 27 28 29 30

HySICSEfficienciesCharacterizedOn-OrbitOn-orbitSI-calibrationobviates

needtotransferground

calibrationtospace

Thisisthewholepurposeofthe

solarcross-calibrationapproach

On-orbitcalibrationscome

frommeasurementsofratios,

soaccuracydoesnotrelyon

absolutecalibrationsoron

long-termstability

EndResult– RadiometricGroundImage• Applyingspectralsolar

irradiancecalibrationsto

theHySICSdataenables

radiometrically-calibrated

datacubes

1233nm

HySICSReferences• G.Kopp,P.Smith,C.Belting,Z.Castleman,G.Drake,J.Espejo,K.Heuerman,J.

Lanzi,andD.Stuchlik,“RadiometricflightresultsfromtheHyperSpectralImager

forClimateScience(HySICS),”GeoscientificInstrumentation,2017,inpress• Kopp,G.,Belting,C.,Castleman,Z.,Drake,G.,Espejo,J.,Heuerman,K.,

Lamprecht,B.,Lanzi,J.,Smith,P.,Stuchlik,D.,andVermeer,B.,“Firstresults

fromtheHyperSpectralImagerforClimateScience(HySICS),”Proc.SPIE 9088,AlgorithmsandTechnologiesforMultispectral,Hyperspectral,andUltraspectral

ImageryXX,90880Q,June13,2014,doi:10.1117/12.2053426

• Kopp,G.,Pilewskie,P.,Belting,C.,Castleman,Z.,Drake,G.,Espejo,J.,

Heuerman,K.,Lamprecht,B.,Smith,P.,andVermeer,B.,“RadiometricAbsolute

AccuracyImprovementsforImagingSpectrometrywithHySICS,”IGARSS2013,Melbourne,Australia,pp.3518-3521,July2013,978-1-4799-1114-1/13.

• Espejo,J.,Belting,C.,Drake,G.,Heuerman,K.,Kopp,G.,Lieber,A.,Smith,P.,and

Vermeer,B.,“AHyperspectralImagerforHighRadiometricAccuracyEarth

ClimateStudies”,SPIEProc.,21-25Aug.2011.• P.Smith,G.Drake,J.Espejo,K.Heuerman,andG.Kopp,“ASolarIrradiance

Cross-CalibrationMethodEnablingClimateStudiesRequiring0.2%Radiometric

Accuracies,”ESTF2011,June2011.

HySICSAccomplishmentsSummary• Designed,built,andtestedahyperspectralimagerforEarthviewing

• Demonstratedflightsolarcross-calibrationtechniqueandquantifiedspectrally-

dependentuncertaintiesfor3attenuationmethodsviatwohigh-altitude

balloonflights

– Aperturearearatios10-3.2,integrationtiming10-3,filters10-0.9

– Netattenuationsof10-7.1 exceedIIP’s10-4.7 goal

– Filterattenuationmethodnotneededforspaceflightinstrument,savingmassandcomplexity

• Demonstrated~2ximprovementinradiometricaccuraciesinflight– Instrumentandcalibrationchangesexpectedtoprovideanother~2ximprovement

• AppliedSI-traceableradiometricscaletomeasuredradiances

• Demonstratedsinglefocal-plane-arrayspectrometerspansdesiredwavelengths

– Reducesmass,volume,power,andcostforspaceflightinstrument

• Improvedground-basedtestfacilityforcalibrationsofsolarattenuatorsystem

andquantificationsofuncertainties

ElevatedTRLfrom3to6

PI: Greg Kopp / LASP

CoIs: Co-I – Peter Pilewskie / LASPBalloon Flight Manager – David Stuchlik / WFF

Build and flight test a hyperspectral imager with improved radiometric accuracies for climate science• 350-2300 nm with single FPA to reduce cost & mass• <0.2% (k=1) radiometric accuracy• <8 nm spectral resolution• 0.5 km (from LEO) IFOV and >100 km FOV• <0.13% (k=1) instrumental polarization sensitivity

Perform two high-altitude balloon flights to demonstrate solar cross-calibration approach and to acquire sample Earth and lunar radiances

Single HgCdTe FPA covers full shortwave spectral range with reduced mass, cost, volume, and complexity

Incorporate solar cross-calibration approaches demonstrated on prior IIP to provide on-orbit radiometric accuracy and stability tracking

Orthogonal configuration reduces polarization sensitivityNo-cost balloon flights from experienced team at NASA

WFF demonstrate on-orbit capabilities

Objective

Approach

HySICS to demonstrate climate science radiometric accuracies in shortwave spectral region

HySICS

LunarReconstruction

GroundReconstruction

SolarDataCube

• HySICSdemonstratesimprovedradiometricaccuraciesbased

onsolarcross-calibrationsunderrealisticflight conditions

• HySICSacquiredrepresentative350-2300nmspatial/spectral

dataoftheSun,Moon,andEarth

• HySICSdemonstratesthefeasibilityofacquiringreflectedsolar

datawithasinglespectrometer

– Reducesmass,power,volume,cost,risk,andcomplexity

• HySICSbuildsonandimprovesneededgroundtestequipment

• HySICSdemonstratesseveralflightcapabilitiesofCLARREO-like

reflectedsolarinstrument

HySICS’ViewofInstrumentTeam

Radiometric Balloon-Flight Results from the HySICS · 2017-04-11 · CLARREO SDT Meeting Hampton, VA, 29 Nov. 2016 HySICS Results Greg Kopp -p. 3 PI:Greg Kopp / LASP CoIs:Co-I –Peter

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