Kurt Squire, 2003 Technology & Cognition Kurt Squire Curriculum & Instruction.
Presenter: Kurt Thome
description
Transcript of Presenter: Kurt Thome
CLARREO Science Team Meeting 8July 2010: N - 1Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Presenter: Kurt Thome
Reflected Solar SuiteKurt Thome, Jason Hair & RS Team
Deputy Project Scientist
CLARREO Science Team Meeting 8July 2010: N - 2Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Requirements includes inter-calibration
RSS RequirementsSocietal Benefit
ScienceObjective
Level 1 Science Requirements
Level 2 Measurement Requirements
Level 2 Mission Requirements
Enable knowledgeable policy decisions based on internationally acknowledged climate measurements and models through:
- Observation of high accuracy long-term climate change trends
- Use the long term climate change observations to test and improve climate forecasts.
Highly accurate and SI-traceable decadal change observations sensitive to climate radiative forcings, responses, and feedbacks:
CL.PRJ.1.REQ.3000•Verif iable on-orbit accuracy•Traceable to SI standards•Decadal climate change relevant time and space scales
CL.SYS.1.REQ.1005 Accuracy demonstrated to be SI traceable to the relevant NIST standard and maintained throughout the sensors lifecycle.
CL.SYS.1.REQ.4002 Observations from 2 Earth orbiting observatories
CL.SYS.1.REQ.4011Observatories designed for a 3-year minimum lifetime. Inf rared spectra
temperature and water vapor feedbackscloud feedbacksdecadal change of :•Temperature prof iles •Water vapor prof iles•Clouds, radiative f luxes•GHG radiative ef fects
CL.PRJ.1.REQ.3001Inf rared radiance spectra of the Earth and its atmosphere with:•Systematic error that corresponds to ≤ 0.1 K radiance calibration uncertainty (3s)•Sampling to provide global coverage and degrade climate trend accuracy by less than 15%
CL.SYS.1.REQ.1001Measurements in the Inf rared Spectra:•Spectral range 200 – 2000 cm -1
•Spectral resolution 1 cm -1 apodized (0.5 unapodized)
•NeDT < 10K (1s), 250-2000 cm -1
•Earth nadir direction, 0.2 deg•GIFOV ≥25 km across•Ground sampling interval ≤ 200 km•Systematic error ≤ 0.100 Kelvin (3s)
CL.SYS.1.REQ.6001 Both observatories in polar orbits:•Orbit Period: 5820.6
0.25 seconds (609 km 200m)
•Inclination: 90 0.1•Eccentricity: ≤0.001•Ground Track Repeat Cycle: 60.83 days (903 distinct paths)
•Ground Track Error: 12.5 km cross track at AN f rom target ground track established by the 60.83 day ground track repeat cycle.
•Plane Separation: 90 in the Right Ascension of the Ascending Nodes (RAAN)
•Time separation: No less than 10 minutes in polar crossing times
Solar ref lected spectra cloud feedbacks snow/ice albedo feedbacksdecadal change of :•Clouds•Radiative f luxes•Snow cover, sea ice, land use
CL.PRJ.1.REQ.3002Solar spectral nadir ref lectance of the Earth and its atmosphere relative to the solar irradiance spectrum with:•Absolute uncertainty ≤ 0.3% relative to global mean ref lected solar energy (2s) •Sampling to provide global coverage and degrade climate trend accuracy by less than 15%
CL.SYS.1.REQ.1002Measurements in the Solar Ref lected Spectra:•Spectral range 320 – 2300 nm•Spectral sampling 4 nm, resolution 8 nm•GIFOV ≤0.5 km by 0.5 km•SNR > 33 for 380 to 900 nm, >20 elsewhere, for 0.3 reflectance, solar zenith angle 75
•Swath width ≥ 100 km•Polarization sensitivity <0.25% (2s) <1000 nm, <0.75% elsewhere
•Radiometric calibration uncertainty ≤0.3% of reflectance
GNSS-ROdecadal change of temperature prof iles
CL.PRJ.1.REQ.3003Atmospheric refractivity with:•Uncertainty of 0.03% for 5-20 km altitude
•Annual means in 10º latitude zones over all longitudes
CL.SYS.1.REQ.1003Measure the phase delay rate of GNSS transmitted signal occulted by the atmosphere:•Altitudes 5-20 km, 200 m vertical resolution•Uncertainty ≤0.5 mm/sec
CL.SYS.1.REQ.1004 Measure averaged microwave ref ractivity:•Over 1 year 10 latitudinal zones, over all longitudes,
•Altitudes 5–20 km, 200 m vertical resolution •Uncertainty ≤0.03 %
NOTEOrbit Def inition considered science sampling requirements and reference intercalibration requirement
Reference inter-calibration•Broadband CERES•Operational sounders (CrIS, IASI) •Operational imagers (VIIRS, AVHRR, Landsat)
CL.PRJ.1.REQ.3010 CLARREO shall enable inter-calibration with climate relevant operational sensors.
CLARREO Science Team Meeting 8July 2010: N - 3Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
• Spectral range: 320 – 2300 nm
• Spectral sampling: ≤4 nm
• Spectral resolution: 8 nm
• Sampling interval at nadir from 600 km orbit: 0.5 km
• Spatial resolution per sample:– 70% of energy from within a 0.5 km x 0.5 km area– ≥ 95% within a 1.0 km x 1.0 km area
• Swath width at nadir from 600 km orbit: >100 km
• SNR values for a single sample (defined for a typical radiance, Ltyp, based on a reflectance of 0.3 and incident solar zenith angle of 75 degrees):
– SNR> 20 for wavelengths 320 – 380 nm– SNR> 33 for wavelengths 380 – 900 nm– SNR> 20 for wavelengths 900 – 2300 nm
• Polarization sensitivity for 100% polarized input:– <0.25% (TBD) below 1000 nm and – <0.75% (TBD) at other wavelengths
• Radiometric calibration accuracy: 0.3% of albedo (integration of reflectance across all wavelengths) and within individual bands
Requirements
RSS Level 2 Requirements
CLARREO Science Team Meeting 8July 2010: N - 4Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Sensor Design
Original RSS Instrument Concept3x Optical Packages• Blue Channel 320-640nm• Red Channel 600-1200nm• NIR (Near Infra-Red) 1150-2300nm
Detector PlaneThermal Radiators
Main Electronics Box(On S/C)
Attenuator wheel Control Electronics
(On S/C)
Instrument Support Platform
Heat Pipes
CLARREO Science Team Meeting 8July 2010: N - 5Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
• Commonality of design of three boxes aids in calibration
• All-aluminum materials including telescope optics
• Offner design• Cooled focal planes tailored
for each spectral region• Depolarizers reduce impact
of scene polarization• Attenuator wheel for
reducing solar irradiance for reflectance retrieval
Single box layout
RSS Instrument Concept Design
InstrumentOptical Bench
SunshieldDetectorAssembly
Detector Electronics
Telescope Optics
Depolarizer Assembly
AttenuatorWheel
CLARREO Science Team Meeting 8July 2010: N - 6Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
CLARREO-1 RSIS Goals• Develop modified instrument concept to coincide with a “single”
instrument spacecraft– Reduce the instrument mass – Fit within funding caps and profiles provided by the project
• Meet all of the RS science requirements including intercalibration
• Proposed solution – reduce three boxes to two boxes– Assume a development plan for CLARREO-1 consisting of
1 Breadboard 1 Prototype/EDU 1 Flight Unit
– The development plan for RSIS on CLARREO-2 depends on what is developed for CLARREO -1
CLARREO Science Team Meeting 8July 2010: N - 7Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
• The RSIS instrument concept for an RSIS dedicated spacecraft revolves around a two spectrometer approach
• Blue spectrometer remains the same– Silicon-based detector– 320 to 640 nm– Single order grating
• Red and NIR spectrometers combined– 600 to 2300 nm– Dual order grating; multi-blazed– HgCdTe detector– Dual attenuator wheel
• Combining the Red and NIR channels into one spectrometer leverages the capability of the MCT detector
2-box design
CLARREO Science Team Meeting 8July 2010: N - 8Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
• Three-box approach was chosen for several reasons– Lowest overall risk– Simpler design, fabrication, build, and test/calibration– Higher component TRL– Detectors had flight history– Depolarizers and attenuators could be tailored spectrally– Characterization/calibration more straightforward
• 2-box approach satisfies many of these– Increased risk to the calibrate the Red/NIR spectrometer due to
the increased stray light from the dual order grating– Mitigate attenuator spectral sensitivity through multiple attenuator
wheels• The specific impacts of the dual order system will have to be
evaluated though the breadboard program
Why not 2-box from the start?
CLARREO Science Team Meeting 8July 2010: N - 9Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Two-box concept
2x Optical Packages• Blue Channel 320-640nm• Red/NIR Channel 600-
2300nm
Detector PlaneThermal Radiators
Main Electronics Box(Inside S/C)
Attenuator wheel Control Electronics(Inside S/C)
Instrument Support Platform
CLARREO Science Team Meeting 8July 2010: N - 10Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Two-box approach
CLARREO Science Team Meeting 8July 2010: N - 11Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
GNSS-RO POD Antenna
Star Trackers
GPS Antennas
CLARREO Science Team Meeting 8July 2010: N - 12Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Instrument• Mass: 67 kg CBE, 86kg with 28% confidence factor• Power: 96 W Avg, 118 W Peak CBE, 125 W Avg, 153 W Peak with 30%
confidence factor• Data Rate: Still being reviewed, but it looks like an allocation of 100
Gbits/day and 150 Mbps Data Rate to the SSR would provide good margin with a 30% confidence factor
• Thermal Radiator: 0.1m^2 mounted on the side of the S/C• Spacecraft pointing control: 360 arcsec control, 72 arcsec knowledge• Spacecraft roll slew rate: up to 2 deg/s• Planned Orbit: 609km• Mechanical Interface: 2 spectrometers mounted to the top of the S/C, 2
Electronics boxes (Main EB, and Attenuator Wheel EB) mounted inside S/C, thermal radiator mounted to S/C cold side
• Electrical Interface: LVDS connection to SSR, 1553 or 422 communication bus
CLARREO Science Team Meeting 8July 2010: N - 13Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
• Baseline approach to reflectance retrieval is ratio of earth-view data to solar-view data
• Single detector scans entire solar disk
• Response of ith detector is
• Bidirectional reflectance distribution function (BRDF) is
Level 1 Science requirement is stated in terms of a reflectance retrieval
Reflectance Retrieval
RS x y
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CLARREO Science Team Meeting 8July 2010: N - 14Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
• Reflectance retrieval, calibration and inter-calibration requirements lead to three basic operating modes
– Solar Calibration– Nadir Data Collection – Inter-calibration of LEO/GEO
assets (avg. 2x per orbit)• Verification of calibration
drives the need for Lunar Views
Three basic operating modes for RSS instrument
Operating Modes
CLARREO Science Team Meeting 8July 2010: N - 15Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
• Solar calibration allows for– Correction of degradation of sensor response
Temporal degradation of detectors and optics Detector-to-detector changes
– Evaluation of stray light• Solar view is non-trivial
– Irradiance source rather than radiance source
– 50,000 times higher energy level
– Requires attenuating approaches
Reflectance retrieval uses direct solar view
On-Orbit, Solar Calibration
Each detector images full solar disk
RS x y
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Solar disk imaged by multiple detectors
CLARREO Science Team Meeting 8July 2010: N - 16Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
• Attenuators provide the 50,000x reduction in solar energy
• All approaches are spectrally dependent• Pinhole Aperture
– Diffraction effects lead to spread of solar “image”– Small-sized aperture affects diffraction grating
dispersion• Perforated Plate
– Avoids materials degradation problems– Trade on size and number of holes relative to
attenuation and beam uniformity• Neutral Density Filters
– Attenuate using either absorption or interference effects– Temporal degradation needs evaluation
Direct solar view requires an attenuating mechanism
Attenuators for Solar Calibration Mode
CLARREO Science Team Meeting 8July 2010: N - 17Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
• CLARREO reflectance retrieval relies on the ratio of the benchmark data to the solar data
– Account for temporal variability in sensor– Can be converted to absolute radiance using a known solar irradiance
• Need to include uncertainties in sensor characterization– Straylight changing
Sensor solid angle (footprint) Sensor aperture Attenuator area
– Detector response uncertainties Nonlinearity Polarization Flat field correction
Calibration overview
B R D FS
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CLARREO Science Team Meeting 8July 2010: N - 18Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Full Calibration
CLARREO Science Team Meeting 8July 2010: N - 19Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
• Each attenuator must be used for solar views
• Lunar verification follows similar scanning
Single-Multiple Image Calibration
CLARREO Science Team Meeting 8July 2010: N - 20Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Flat-Fielding Calibration
CLARREO Science Team Meeting 8July 2010: N - 21Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
• Characterize the sensor to SI-traceable, absolute radiometric quantities during prelaunch calibration
Watt Irradiance mode Radiance mode
• Determine geometric factors for conversion to reflectance
– On-orbit calibration “validates” the prelaunch calibration
– Solar and lunar views used to determine temporal changes
• Key is to ensure prelaunch calibration simulates on-orbit sources
– Absolute irradiance calibration for solar view
– Simulated geometry of solar and lunar views for stray light
• Successful transfer to orbit achieved when sensor behavior can be accurately predicted
Simulating and predicting on-orbit sources is basis of calibration
Calibration Approach
Prelaunch LaboratoryMeasurements
No
CalibratedYes
Sensor Model
Model/Measurment
Agree?
On-Orbit SensorMeasurements
On-Orbit SensorMeasurementsPredicted On-Orbit
Sensor Output
UpdateModel
CLARREO Science Team Meeting 8July 2010: N - 22Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Meeting L1 Measurement Requirements
• The effort is determining the measurements needed to satisfy/understand the development of the sensor model
• Preliminary independent study indicated CLARREO Reflected Solar requires nearly order of magnitude improvement in radiometric accuracy
• Dominant error sources identified as stray light and attenuator characterization
• Efforts to reduce these errorsources rely on
– Minimizing sensor complexity– Choosing appropriate approaches for SI traceability– Emphasizing calibration throughout sensor development lifecycle
RS Calibration
No
Model/Measurment
Agree?
On-Orbit SensorMeasurementsPredicted On-Orbit
Sensor Output
UpdateModel
CLARREO Science Team Meeting 8July 2010: N - 23Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Calibration Overview
* Measurements to achieve SI traceability for transfer to orbit
AttenuatorcharacterizationA Ta ttenua tor a ttenua tor,
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Absoluteresponse
Relativeresponse
Sensor Artifactsa a
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Green box showsdominantparametersdetermined fortransfer to orbit
*
*
Prelaunch OperationsPost-launch
CLARREO Science Team Meeting 8July 2010: N - 24Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
• Attenuator verification relies on trending of lunar views without attenuator
– Compare to trend of sensor output while viewing sun with attenuator in place
– Different trend behavior indicates attenuator issue• Comparison of solar irradiance reported by CLARREO to other on-
orbit sensors indicates whether absolute calibration is maintained in going to orbit
– Indicates whether geometric factors are well understood (attenuator area)
– Stability of absolute detector response• Relative response measured in laboratory compared to that derived
on orbit for consistency• Artifact determination
– Sun and moon provide sharp boundaries for stray light, ghosting– Stellar and planetary sources provide point sources for evaluation of
spatial response– Polarization sensitivity assessed using earth-view scenes (e.g., ocean
views at large angles)– Non-linearity evaluated by varying attenuators– Size of source effect is most difficult to issue to understand
Calibration overview
Attenuatorverification A Tattenu a tor a ttenu a tor,
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Relativeresponse
Sensor Artifactsa a
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*
*
Post-launch
CLARREO Science Team Meeting 8July 2010: N - 25Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
SIRCUS Traceability
Meeting L1 Measurement Requirements
• SIRCUS provides a feasible option for simulating on-orbit sources
• Absolute response• Stray light
• SIRCUS relies on a set of well-understood tunable lasers
– Variety of techniques used to condition laser output
– Output characterized by CLARREO Transfer Radiometer and monitors on sphere
• Provides a monochromatic source that can achieve 0.1% absolute uncertainty
* POWR – Primary Optical Watt Radiometer
CLARREO Science Team Meeting 8July 2010: N - 26Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
SIRCUS and CLARREO
Meeting L1 Measurement Requirements
• Ultimate goal is to have a portable SIRCUS-like facility for calibration of RS instrument
• Portability needed to ensure its use at a vendor facility• Necessary to achieve needed accuracy
• SIRCUS-like facility includes• Monochromatic source
• Irradiance• Radiance• Cover full spectral range of CLARREO
• Broadband transfer radiometers• Monitor output of source
• Transfer radiometer #1 – VNIR• Transfer radiometer #1 - SWIR
• Maintain traceability to NIST laboratories• Transfer radiometer #2 – VNIR• Transfer radiometer #2 - SWIR
CLARREO Science Team Meeting 8July 2010: N - 27Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Inclusion of SIRCUS for CLARREO• Including a SIRCUS-like source in the preflight calibration chain permits preflight,
absolute radiometric calibration of solar view to better than 0.2%• Diagram below gives top-level error sources and expected error budget
Meeting L1 Measurement Requirements
ElectronicsOffset
EarthView k=2
0.08% 0.05%Sensor
Characteristics
Jitter
BackgroundOffset
0.1%0.05%
DetectorsROIC
Analaog
Inclusion ofSIRCUS
reduces strayand scattered
lightuncertainties by
>1 order ofmagnitude
ROIC ReadNoise
Quantization Noise
Electronics Noise
Near-FieldBackground
Noise
Dark Current Noise
Signal PhotonNoise
IntegrationTime
Optical Efficiency
WavelengthCalibration
Point SpreadFunction
PolarizationSensitivity
Line SpreadFunction
Responsivity and Rel. Gain
Detector Linearity
SceneThermal
ScatteredLight
Stray Light and Flare
Sensor Thermal
RadiometricRandom
Boresight
Random
Non-random
0.3% on singlemeasurement
0.1%
Sensor thermal is afterdark subtraction
Thermal backgroundimportant at λ>1.8 μm
CLARREO Science Team Meeting 8July 2010: N - 28Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Broadband Approaches• Sources calibrated in SIRCUS-like measurements are limited in bandpass
– Small regions of wavelength can be tested– Cannot calibrate all CLARREO spectral and spatial detectors simultaneously
• Hyperspectral Image Projector (HIP) currently under development at NIST would provide a broadband source
– Can match desired spectral source– Traceablity can be achieved through a SIRCUS-like calibration– Also provides opportunity to develop a solar simulated source
• SIRCUS and HIP can be replicated at a CLARREO facility
Meeting L1 Measurement Requirements
HIP schematic
CLARREO Science Team Meeting 8July 2010: N - 29Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
• Clearly the key technology developments are– SIRCUS facility– RS Transfer Radiometer
• A SIRCUS-based absolute calibration in radiance is currently demonstrated by NIST at the 0.2% accuracy
– Stray light is readily characterized by a SIRCUS-based calibration– Polarization sensitivity measurements are also feasible with SIRCUS
• Focus on developing broadband calibration techniques– HIP can be used to bridge the broadband gap
More development to understand the accuracy Prototype development scheduled to be complete in 18 months
– Characterization of filtered transfer radiometers by SIRCUS also permits extension to broadband sources
• Significant technology development is not required but rather advancements in current approaches are needed
– Robust, portable SIRCUS facility– Transfer Radiometers with sufficient spectral coverage– Broadband stray light and polarization systems of sufficient fidelity
Requirements Compliance
Technology Development/Path to 0.3%
CLARREO Science Team Meeting 8July 2010: N - 30Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Error Budget• Radiometric calibration
requirements of RSS instrument can be met with currently-available approaches
• Requires inclusion of NIST-based methods
– Detector-based transfer radiometers
– Narrow-band SIRCUS aproaches
– HIP-based scene projections
B R D FR S
R S r
T AA
a ar r ri j
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Meeting L1 Measurement Requirements
Line SpreadFunction Artifacts
EarthView
Reflectanceuncertainty
0.1% 0.03%
0.3%
0.2%
0.1%
0.2%
Earth:SolarRatio
SolarView
Spectral
Solar AttenuatorFactor
WavelengthCalibration Artifacts
Percentuncertainties inreflectance; k=2
CLARREO Science Team Meeting 8July 2010: N - 31Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Calibration Flow
RS Calibration
Assemble FLT Optics Package(Blue Band)
Assemble FLT Instrument(3 Boxes)
Ground Operations
Post-Launch Operations
Thermal/Vac Test- Survival -
BalanceDeep Calibration
Thermal/Vacuum Test
Calibration Stability Check
Requirements Verification
Environmental Test
Subsystem/Component
Measurements
Assemble FLT Optics Package(Red Band)
Thermal/Vac Test- Survival -
BalanceDeep Calibration
Requirements Verification
Environmental Test
Subsystem/Component
Measurements
Assemble FLT Optics Package(NIR Band)
Thermal/Vac Test- Survival -
Balance
Deep Calibration
Requirements Verification
Environmental Test
Subsystem/Component
Measurements
Requirements Verification
Environmental Test
Acceptance Review
Delivery to Payload I&T
Payload I&T
Thermal/Vacuum Test
Calibration Stability Check
Payload Delivery to Spacecraft I&T
Requirements Verification
Environmental TestSpacecraft I&T
Thermal/Vacuum Test
Calibration Stability Check
LaunchRequirements Verification
Environmental Test
Post-Launch Checkout
In-Orbit Calibration Validation
CLARREO Science Team Meeting 8July 2010: N - 32Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
• Aperture and Grating Quantity Trade Study– Proceed with 3 Aperture, 3 Grating Design
Lowest overall Risk Simpler design, fabrication, build, and test Lower cost Higher component TRL
• Detector Material Trade Study– Blue Band Material Selected – Silicon; Red and NIR Band Material Selected – MCT (substrate
removed) Only consider main-stream detector technology Only consider materials with flight history Meets Spectral Requirement
• Wavelength Range Trade Study– Spectral range to cover from 320 to 2300 nm
Upper limit chosen due to loss of signal from reduced solar irradiance and strong water vapor and carbon dioxide absorption
Short-wavelength limit chosen to provide sufficient spectral range for accurate retrieval of total shortwave flux
• Polarization Requirements Trade Study– Polarization sensitivity <0.50% below 1000 nm and <0.75% at other wavelengths for a 100% polarized
input Value required to limit uncertainty in benchmark data set to contribute <0.1% of total radiometric calibration
budget
Trade Studies
Trade Studies Completed
CLARREO Science Team Meeting 8July 2010: N - 33Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Inst #2250K
Inst #1270K
Inst #3230K
Per pixel SNR requirement
7 11 7
Worse case detector temps
Requirements Compliance
Radiometric Performance Margin: Ltyp; Sun View; Lmax
2.8E6 pe’sWell Capacity
Wavelength - um
Inst #129.7ms integration
Inst #26.8ms integration
Inst #37.1ms integration
2.8E6 pe’sWell Capacity
Wavelength - um
Inst #129.7ms integration
Inst #26.8ms integration
Inst #37.1ms integrationInst #2
250K
Inst #1270K
Inst #3230K
Per detector SNR requirement
67 67110
Worse case detector temps
CLARREO Science Team Meeting 8July 2010: N - 34Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Dual-Double Wedge Depolarizer with OA at 90, Wedge angles clocked at 45
Polarization Sensitivity Compliance
Requirements Compliance
Add text description; label requirements lines; define DOLP
CLARREO Science Team Meeting 8July 2010: N - 35Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
• Phase A breadboard and EDU development requires a parallel development of calibration GSE• Calibration development plan also includes development of calibration methods and protocols
applicable for flight instruments• Calibration development plan follows Phase A plans to reduce instrument risks and close trades
– Solar/earth view ratio for reflectance Laboratory capability to provide irradiance (point) source and radiance (extended ) source Solar- and lunar-based measurement capability Geometric characterization of sensor field of view
– Attenuator characterization Spectral transmittance Aperture-area measurements
– Path to SI traceability (source and detector standards) Narrow-band source (SIRCUS) Broad-band source (HIP) Transfer radiometers
– Stray light modeling capability– Polarization sensitivity measurement
Component-level depolarization characterization System-level polarization sensitivity
– Focal plane and grating characterization Uniformity Stability Noise
Phase A plans
CLARREO Science Team Meeting 8July 2010: N - 36Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Long Lead Procurements
Component Fabrication, Procurement
Breadboard Plan
Component Characterization
Optical Package Assembly
Performance Test and Calibration
Earth, Sun, Moon Measurements
May 2011
Layout &Analysis
Aug 2011
ComponentFab, Procure
Dec 2011
Optics PackageAssembly
Comp.Charact.
Oct 2011
Perf. Test,Cal.
March 2012
Earth, Sun,Moon Meas.
April 2012
Calibration(incl. NIST)
July 2012Aug 2010
Long Lead Procurement Start(Detector, Grating, Depolarizer)
Layout and Analysis
Characterization and Calibration
Description• Detectors• Depolarizers• Gratings
Risk Reduction• Items available when other
parts ready
Description• Measure Performance
• Detectors• Depolarizers• ND Filters• Gratings/Optics
Risk Reduction• Validate analytical
performance models with measured performance
• Measure Detector noise levels, Validate noise reduction by averaging
• Evaluate stray light
Description• Develop a breadboard
based on the blue band spectrometer
Risk Reduction• Allows lower cost breadboard
development using Si detectors• Focuses effort on component
and calibration risk mitigation
Description• Calibrate with a NIST
traceable FEL Lamp• Flat Panel, Spherical
Integrator Cal.
Risk Reduction• Begin NIST traceable
calibration• Begin developing cal.
processes
Description• Measure Sun and Earth to
generate Reflectance• View Moon and Sun
Risk Reduction• Begin to validate operations
approaches• First time that Sun and Earth
will be viewed to generate Reflectance
Description• Continue cal. evaluation
with GSFC facilities• Calibrate with SIRCUS
at NIST
Risk Reduction• Continue NIST traceable calibration to
higher accuracies• Begin developing cal. processes• Evaluate the ability to calibrate the
design
CLARREO Science Team Meeting 8July 2010: N - 37Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Breadboard Plan• Breadboard plan was modified slightly in March
– Build an optical package starting with the Blue band (320-1150 nm) design Blue band selection will allow achievement of more objectives than any other band (items 1,2,4,5, and 6)
quicker, with possibly lower cost options for detectors– Build optical package for the Red/NIR band (600-2300 nm) designs– Evaluate detector options based on cost, with the possibility of a stepped approach of cheaper vs.
more functional detectors to begin a stepwise learning and testing approach based on available budget– The optical package would have a feature for using attenuators– Validate reflectance retrievals in laboratory and field– NIST-based measurements to evaluate calibration techniques and error budgets
• Breadboard objectives– Demonstrate the ability to view the sun and the scene and output reflectance by taking the ratio of the
Solar irradiance and the measured value Feasibility of attenuation methods: perforated plate, pinhole plate, neutral density filters
– Develop and check calibration protocols and methods Path to SI traceability (source and detector standards)
– Demonstrate the ability to design and produce optics, with the optics in the Blue band (320-1150 nm) being the most challenging
– Demonstrate ability to minimize polarization sensitivities– Demonstrate the ability to control and characterize stray light including multiple-order gratings– Demonstrate the ability to measure shortwave IR (600-1200nm) (Red)
Demonstrate the use of detector technology Validate ability to control thermal stability Make measurements past 900nm
CLARREO Science Team Meeting 8July 2010: N - 38Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
Calibration Development Plan• Phase A breadboard and Prototype development requires a parallel development of calibration GSE• Calibration development plan also includes development of calibration methods and protocols applicable for flight
instruments• Calibration development plan follows Phase A plans to reduce instrument risks and close trades
– Solar/earth view ratio for reflectance Laboratory capability to provide irradiance (point) source and radiance (extended ) source Solar- and lunar-based measurement capability Geometric characterization of sensor field of view
– Attenuator characterization Spectral transmittance Aperture-area measurements
– Path to SI traceability (source and detector standards) Narrow-band source (SIRCUS) Broad-band source (HIP) Transfer radiometers
– Stray light modeling capability– Polarization sensitivity measurement
Component-level depolarization characterization System-level polarization sensitivity
– Focal plane and grating characterization Uniformity Stability Noise
CLARREO Science Team Meeting 8July 2010: N - 39Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
NIST Standards Development
• NASA/NIST personnel work collaboratively to develop portable SIRCUS• Obtain NIST SIRCUS schematics and parts list
•Finalize development plan based on tests conducted in NIST’s prototype facility
•Design transfer radiometers•Procure parts•Breadboard development
•Procure additional parts (e.g., integrating sphere, speckle removal system)•Begin assembly at GSFC
•Procure parts •Begin assembly
•Conduct testing to establish standard uncertainties in irradiance and radiance responsivity calibrations to less than 0.1%
•Conduct testing to establish instrument radiometric scale•Deliver DMD to GSFC
•Deliver CXRs to GSFC•Integrate with portable SIRCUS
Design a portable version of the NIST SIRCUS facility
Procure tunable lasers to cover desired wavelength range
(320nm – 2300nm)
Assemble SIRCUS facility
Outcome: Provides monochromatic source that can achieve 0.1% absolute accuracy of irradiance sources
FY 2011 FY 2012 FY 2013 FY 2014
Design CXRsConstruct/Test CXRs
(coverage from 320 nm to 2300 nm)
Complete testing of CXRs
Outcome: Enables SI-traceable radiance
comparisons in the UV, visible, and near-infrared
Design DMD-based spectrally tunable calibration source
Outcome: Provides a broadband source that can
reproduce expected reflected solar brightness
levels and spatial distributions
Assemble DMD Complete TestingDMD
Complete TestingSIRCUS
CLARREO Science Team Meeting 8July 2010: N - 40Use or disclosure of the data contained on this sheet is subject to the restrictions on the IMR cover page
• Activities of breadboard relevant to SIRCUS– Develop and check calibration protocols and methods
Path to SI traceability Detector-based methods
– Demonstrate the ability to control stray light– Demonstrate the ability to measure shortwave IR (600-1200nm)
(Red)• Development of SIRCUS-like facility takes place during
breadboard work– Not necessary to complete SIRCUS for breadboard– Necessary to understand how it would be used
• Higher fidelity error budget
Breadboard and SIRCUS