VIIRS Sensor Performance - SSEC, UW-Madison VIIRS Sensor... · Copyright © 2003 Raytheon Company...

Copyright © 2003 Raytheon CompanyAn unpublished work. All rights reserved.

NPOESS Visible Infrared Imaging Radiometer Suite (VIIRS) Sensor Design and Performance

J. Puschell1, C. Schueler1, J. Ed Clement1, R. Ravella1, L. Darnton2

F. DeLuccia3, Captain T. Scalione USAF4, H. Bloom4, H. Swenson3

1Raytheon Santa Barbara Remote Sensing2Northrop Grumman Space Technology

3The Aerospace Corporation4NPOESS Integrated Program Office (IPO)


VIIRS System to Provide Excellent Environmental Data Records (EDRs)

• VIIRS System Design based on integrated Sensor and Algorithms• Engineering Development Unit (EDU) approaching integration• EDR Science Algorithms developed, documented, and publicly released by Raytheon Technical Services Company (RTSC) Information Technology and Scientific Services (ITSS)

Imagery (with four ARRs)Sea Surface Temp

Aerosol Optical ThicknessAerosol Particle Size

Suspended MatterCloud Cover/Layers

Cloud Effective Particle SizeCloud Optical Thickness

Cloud Top HeightCloud Top Pressure

Cloud Top TemperatureAlbedo

Land Surface TemperatureVegetation Index

Snow Cover/DepthSurface Type (ST)l

Fresh Water Ice(Sea Ice ARR)Ice Surface Temperature

Ocean Color/Chlorophyll Sea Ice Characterization

Active Fires (ST ARR)Precipitable WaterCloud Base Height

Net Heat FluxSoil Moisture

IA

IIA

IIB

IIIB

IORD/TRD Threshold IORD/TRD Objective


VIIRS PerformanceVerified by Hardware & Testbed

Snow/Ice

Snow/Ice

SurfaceTemp.

SurfaceTemp.

OceanOcean

TOA*Scene

Radiance

TOA*Scene

Radiance

Algorithms: (VIIRS Subsystem)Sensor: (VIIRS Subsystem)

VIIRS System

CoolerCooler

CloudsClouds

LandLand

AerosolsAerosols

RotatingTelescopeRotatingTelescope

Aft Optics/FPAs

Aft Optics/FPAs

SDRProcessing

SDRProcessing

RDRProc-essor

RDRProc-essor

ImageryImageryOn-BoardCalibratorsOn-Board

Calibrators

Auxiliary & Ancillary

data

Auxiliary & Ancillary

data

ClosedClosedthethe

Loop!Loop!

*Top ofAtmosphere

• EDRs drive algorithm and raw sensor data requirements• Sensor specification derived from EDRs with testbed• Sensor performance verified by hardware risk-reduction demonstrations and analyses

• EDR performance verified by testbed with sensor models


VIIRS Sensor Performance Defined by Sensor Specification

Sensor Performance Requirements

Scan

56.26o

40 rpm

Radiometric

Typical Radiance (Ltyp)

Dynamic range

SNRAlignment

Pointing

Registration

Spatial

GIFOV

HSI

MTF

Calibration

Pre-launch

On-orbit

Stability

Other

Uniformity

Linearity

Stray light

Crosstalk

Spectral

Tolerances

Band center

Bandwidth

Out-of-band

response

In this presentation

In VIIRS specification

• Northrop-Grumman Space Technology (NGST) contract to Raytheon Santa Barbara Remote Sensing (SBRS) based on sensor specification

• NPOESS Integrated Program Office (IPO) contract to NGST based onsystem specification including EDR performance


Radiative Cooler/Earth Shield

Photons to Digital Data: VIIRS Architecture Stable Since PDR

SolarDiffuser

Blackbody

Sun

SpaceView

Earth

RotatingTelescopeAssembly

FPADewar

Focal PlaneElectronicsReadout &

A/DConversion

FormatterBuffer

Compression

Data

Power, Command,Control, Telemetry

LWIR (4)

SWIR/MWIR (8)

Beam-splitter

SDSM

Beam-splitterBeam-splitter

Imager DNB/VNIR(10 bands)

GroundSupport

andSystem TestEquipment

Dimensions: 134 x 141 x 85 cmMass: 275 kgPower: 240 WData Rate: 10.5 peak/8 avg Mbps

DNB - Day/Night “Band”VisNIR - Visible/Near IRSWIR - Short Wave IRMWIR - Mid Wave IRLWIR - Long Wave IRHAM - Half Angle Mirror SDSM - Solar Diffuser Stability Monitor

HAM

Moon

SpaceView


VIIRS Post-CDR RefinementsBeing Verified in EDU*

• Constant-speed rotating telescope• Simple all-reflective diamond point

turned bolt-together optics• Proven emissive/reflective calibration

Passive Cryoradiator

4-mirror anastigmatAll-reflective

Aft optics imager

3-Mirror AnastigmatRotating telescope refined to eliminate modulated instrument background (MIB)

MODIS-heritage blackbodyrelocated to minimize Earth shine

MODIS-heritage Solar Diffuser screen redesigned to minimize solar modulation

Electronics module (EM) & cables refined to minimize EMI

Cold FPADewar Assembly

MODIS-heritageSolar DiffuserStability Monitor refined to improve performance


VIIRS Compact, All ReflectiveNon-Image Rotating Optical Design

Rotating Telescope Assembly (RTA)

Half Angle Mirror (HAM)

FMA Imager

SWIR/MWIR& LWIR Dewar

VNIR/DNB FPA

Key post-CDR redesign:Moved aperture stop from primary mirror to just aft of HAM to keep source of detected rays within primary mirror, mitigating MIB

HAM rotates at half RTA speed in same direction to eliminate image rotation


Follow the Photon!


Sensor Models Being Verified byEngineering Development Unit (EDU) Tests

Mainframe: G, H

Rotating Telescope: A, B

Aft Optics: A, B

ElectronicsModule (EM): G

Half-Angle Mirror: I

All Optics:

C,D,E,F,H

FPAs & EM:

A,B, H, IFocal Planes

(FPAs): J

IHGFEDCBA163231 153029 142827 132625 122423 112221 102019 91817 81615 71413 61211 5109487365243121

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CABLE SIDE

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CK

Solar Diffuser Solar DiffuserStability Monitor

BlackbodyReference

On-Board Calibration Mechanisms: A

Legend Model Description

A Signal to Noise Ratio (SNR)

B Modulation Transfer Function (MTF)

C Polarization Performance

D Sequential Ray Trace

E Non-sequential Ray Trace

F Thin Films Design and Performance

G Structural Design and Performance

H Thermal Design and Performance

I Electronics Simulation

J Focal Plane Array (FPA) Performance


Spectral, Spatial & Radiometric Attributes of 22 VIIRS Bands

Nadir End of Scan Required Predicted MarginM1 0.412 0.742 x 0.259 1.60 x 1.58 Ocean Color Low 44.9 352 441 25%

Aerosols High 155 316 807 155%M2 0.445 0.742 x 0.259 1.60 x 1.58 Ocean Color Low 40 380 524 38%



Aerosols High 90 315 638 102%I1 0.640 0.371 x 0.387 0.80 x 0.789 Imagery Single 22 119 146 23%M5 0.672 0.742 x 0.259 1.60 x 1.58 Ocean Color Low 10 242 298 23%

Aerosols High 68 360 522 45%M6 0.746 0.742 x 0.776 1.60 x 1.58 Atmospheric Corr'n Single 9.6 199 239 20%I2 0.865 0.371 x 0.387 0.80 x 0.789 NDVI Single 25 150 225 50%M7 0.865 0.742 x 0.259 1.60 x 1.58 Ocean Color Low 6.4 215 388 81%

Aerosols High 33.4 340 494 45%DNB 0.7 0.742 x 0.742 0.742 x 0.742 Imagery Var. 6.70E-05 6 5.7 -5%

M8 1.24 0.742 x 0.776 1.60 x 1.58 Cloud Particle Size Single 5.4 74 98 32%M9 1.378 0.742 x 0.776 1.60 x 1.58 Cirrus/Cloud Cover Single 6 83 155 88%I3 1.61 0.371 x 0.387 0.80 x 0.789 Binary Snow Map Single 7.3 6.0 97 1523%

M10 1.61 0.742 x 0.776 1.60 x 1.58 Snow Fraction Single 7.3 342 439 28%M11 2.25 0.742 x 0.776 1.60 x 1.58 Clouds Single 0.12 10 17 66%I4 3.74 0.371 x 0.387 0.80 x 0.789 Imagery Clouds Single 270 K 2.500 0.486 415%

M12 3.70 0.742 x 0.776 1.60 x 1.58 SST Single 270 K 0.396 0.218 82%M13 4.05 0.742 x 0.259 1.60 x 1.58 SST Low 300 K 0.107 0.063 69%

Fires High 380 K 0.423 0.334 27%

M14 8.55 0.742 x 0.776 1.60 x 1.58 Cloud Top Properties Single 270 K 0.091 0.075 22%M15 10.763 0.742 x 0.776 1.60 x 1.58 SST Single 300 K 0.070 0.038 85%I5 11.450 0.371 x 0.387 0.80 x 0.789 Cloud Imagery Single 210 K 1.500 0.789 90%

M16 12.013 0.742 x 0.776 1.60 x 1.58 SST Single 300 K 0.072 0.051 42%

Driving EDRsRadi-ance

Range

Ltyp or Ttyp

Signal to Noise Ratio(dimensionless)

or NE∆T (Kelvins)

CCD

Horiz Sample Interval(km Downtrack x Crosstrack)Band

No.Wave-length (µm)

VIS

/NIR

FP

AS

ilicon

PIN

Dio

des

S/M

WIR

PV

HgC

dTe

(HC

T)PV

HC

TLW

IR


Finer Sampling, Spatial Resolution & Better Sensitivity

1.2km

1.1k

m

1.6km

1.6k

m

0.75km

0.75

km

Fine-Resolution Imaging ‘I’ Bands

Moderate-Resolution (“Radiometric”) ‘M’ Bands

Day-Night Band ‘DNB’

0.74

km

0.74km

0.74

km

0.74km

0.74

km

0.74km

M M M

I DNBDNBDNB II

SNR predicted and specified at worst-case edge of scan: ~60% better nadir SNR and finer spatial resolution


VIIRS Provides Operational Data Continuity in Many Areas,

Including Ocean Color*

• 5 year mission –aproaching 6 years

• Verified ocean color benefits

• Eight bands

• 5 year life• Nine ocean color

bands• Ocean color one of

many applications

• 7 year life• Seven ocean color

bands• Ocean color supports

other VIIRS EDRs

NASA EOS MODIS(1999)

NPOESS VIIRS(2006 NPP)

Commercial &Research Research OperationalSeaWiFS

(1997)

*With VIIRS improvements: e.g., dual-gain, finer spatial resolution, better sensitivity, etc.


VIIRS Model Predicts Excellent Polarization Sensitivity Margin

VIIRS Band

Bandcenter(nm)

Polarization Specification

(%)

-45 degrees

Zero degrees

+45 degrees

M1 412 3.0 1.30 2.00 2.90

M4 555 2.5 0.50 0.30 0.60

I2 & M7 865 3.0 0.70 0.04 0.02

Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center and ORBIMAGE


Detailed Thermal Modeling Predicts On-orbit Temperature Variations

HAM cavity (1041)HAM cavity (1042)HAM cavity (1048)

HAM cavity (1092)HAMAft optics

Time, minutes

Tem

pera

ture

, K

Thermal model 1730 orbit, hot

0 20 40 60 80 100 120 140 160 180 200 220

277

278

279

280

281

282

276





Time, minutes

Tem

pera

ture

, K

Thermal model 1730 orbit, hot

0 20 40 60 80 100 120 140 160 180 200 220

277

278

279

280

281

282

276

• Detailed VIIRS thermal model predicts sensor structure and optics element temperatures vs. orbit and time: Greatest variations in 1730 (terminator) orbit

• Detailed calibration model uses results to predict emissive band radiometric accuracy: Model predicts specification margin in all bands


Detailed SST-band Error Budget with On-orbit Temperature Variations

VIIRS Center Wavelength (µm)Parameter

3.70 4.05 8.55 10.76 12.01Ttypical (K) 270 300 270 300 300Temperature knowledge effect (%) 0.32 0.24 0.14 0.09 0.08Wavelength knowledge effect (%) 0.20 0.20 0.04 0.03 0.04Integrated out-of-band effect (%) 0.30 0.30 0.20 0.10 0.10Response vs. scan angle knowledge (%) 0.20 0.20 0.60 0.20 0.20Response vs. scan angle pedestal knowledge 0.20 0.20 0.60 0.20 0.20Emittance knowledge (%) 0.20 0.20 0.20 0.20 0.20Electronic crosstalk (%) 0.20 0.20 0.20 0.20 0.20Ghosting (%) 0.24 0.24 0.24 0.24 0.24Polarization knowledge effect (%) 0.01 0.01 0.10 0.10 0.10Earthshine effect (%) (Tearth=343K) 0.029 0.025 0.009 0.008 0.007Solar diffuser screen emission (%) (Tinst=285K) 0.0293 0.0245 0.0091 0.0076 0.0071Solar diffuser Sunlight Scatter (%) 0.128 0.110 0.047 0.041 0.038Blackbody Skin Temp Effect (%) (Tinst=275K) 0.014 0.003 0.0 0.0 0.0Surround Correction Effect (%) (Tinst=285K) -0.031 -0.028 -0.013 -0.011 -0.01

Radiometric Calibration Model σ (%) 0.68 0.62 0.55 0.35 0.35Allocation Requirement (%) 0.7 0.7 0.6 0.4 0.4MODIS SST image courtesy NASA @http://visibleearth.nasa.gov/data/ev2/ev284_global_SST_sm.jpg


Engineering Development Unit (EDU) Approaching Integration Phase

Cryoradiator, 30%

Aft Optics Assembly (including FPAs), 40%

Scan Motor, 50%

Telescope Assembly, 50%

Solar Diffuser Stability Monitor, 80%

Cryoradiator Door, 30% Focal Plane Interface Electronics

Electronics Module, 70%

Half Angle Mirror & Motor Assembly, 50%

Nadir Radiator Panel

Solar Diffuser

Blackbody

Mainframe

: completedor ~%complete

Nadir Aperture Doors, 30%


EDU Focal PlanesVerified Design

•All EDU FPAs assembled and tested, including detectors & read-out integrated circuits (ROICs)

•S/MWIR & LWIR FPAs: Photovoltaic (PV) HgCdTewith integrated “Microlens” technology to reduce background noise

•All PV HgCdTe allows LWIR time-delay and integration (TDI) and lowers crosstalk

•Optical alignment of all FPAs provides optimum band-band registration

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Band I5 Noise Equivalent Irradiance

1.00E+122.00E+123.00E+124.00E+125.00E+126.00E+127.00E+12

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31

Pixel Number

NEI

, ph/

cm^2

-s

Band I5 DC Uniformity @ Qtyp

-3.500

-3.300

-3.100

-2.900

-2.700

-2.500

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31

Pixel Number

Sign

al V

olta

ge, V


EDU Testing Lowers Risk for Flight Unit Integration & Test

96-0

2-08

5

Software, Documentation,and Engineering Analysis Engineering Development Unit

Ground Support Equipment Shipping/Storage

FlightInstruments NPP model (2005)

C1 model (2006)

First Flight Unit

• Calibration and Test• Performance Assessments

EDU Lessons Learned

• Integration• Calibration and Test• Performance Assessments


VIIRS on-track to EDU Integration & NPP Flight Unit Development

• National Polar-orbiting Operational Environmental Satellite (NPOESS) Visible Infrared Imaging Radiometer Suite (VIIRS) approaching Engineering Development Unit (EDU) integration

– Several design refinements lowered EDU and flight unit development and test risks

– Principal post-CDR optics design change to correct modulated instrument background (MIB) approved

– Sensor specified for excellent EDR performance: Refined design offers margin to sensor specification

– Detailed quantitative sensor performance modeling completed and partially verified by EDU hardware tests

– Remaining EDU fabrication and testing will verify models or identify corrective action

• First flight unit for NPOESS Preparatory Project (NPP) scheduledfor completion in 2005 for 2006 launch

• Second flight unit for NPOESS initial operational launch in 2130orbit scheduled for completion in 2006 for 2009 launch

VIIRS Sensor Performance - SSEC, UW-Madison VIIRS Sensor... · Copyright © 2003 Raytheon Company...

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Transcript of VIIRS Sensor Performance - SSEC, UW-Madison VIIRS Sensor... · Copyright © 2003 Raytheon Company...