CLARREO Science Meeting July 2010 MGM: 5a- 1 Presenter: Marty Mlynczak Infrared Instrument Overview - CLARREO Infrared Team CLARREO IR Science Lead

CLARREO Science Meeting July 2010 MGM: 5a- 2 IR Requirements, Concept, Calibration Drivers, etc. Review Instrument Re-Scope Study Current Radiometric Modeling –Measured Pyroelectric Detector Performance –Updated Noise Performance –Updated Systematic Uncertainty Assessment NIST Activities –Investments in FY2011 Overview of Phase-A Planning Status, Concerns, Summary Outline

CLARREO Science Meeting July 2010 MGM: 5a- 3 Infrared Baseline Science Measurement: CLARREO shall obtain infrared radiance spectra of the Earth and its atmosphere using nadir views from orbiting satellites. The benchmark and reference intercalibration measurements require: a Broad spectral coverage of the earth emitted spectrum, including the Far- Infrared, that captures climate trend information about atmospheric structure, composition, clouds, and surface properties; b Spectral resolution chosen for greenhouse gas species separation and for vertical structure information; c Radiance measurement systematic error that corresponds to < 0.1 K brightness temperature radiometric calibration uncertainty (3-  confidence, excluding random noise) for the range of expected earth scene temperatures and wavelengths relevant to climate; d Spatial and temporal sampling sufficient to provide global coverage and reduce sampling errors to levels that degrade the measured climate trend accuracy by less than 15%, and that degrade the time to detect climate trends less than 10%. The degradation of trend accuracy is relative to the limits of accuracy caused by climate natural variability. Level 1 IR Requirements

CLARREO Science Meeting July 2010 MGM: 5a- 4 Spectral Range: 200 to 2000 cm -1 (2760 cm -1 goal) –Rationale:  Spectral Range for Climate Benchmark and Fingerprinting  Spectral Range for Reference Intercalibration of Longwave Broadband Sensors (CERES; GERB; Megha-Tropiques) Spectral Resolution: 0.5 cm -1 unapodized –Rationale:  Ability to resolve effects of temperature and water vapor as functions of altitude Systematic Uncertainty : Kelvin (3 , i.e. coverage factor, k=3) –Rationale:  0.1 K is half of the expected trend in global temperature change per decade IFOV: No less than 25 km –Rationale: Enables climate record, reference intercalibration Ground sampling: One calibrated spectrum every 200 km or less –Rationale: Nyquist samples the autocorrelation length of the radiation field Nadir Viewing within +/- 0.2 deg –Rationale: Keeps temporal bias between satellites < few milli-Kelvin Level 2 requirements defined Level 2 IR Instrument Requirements CL.SYS.1.REQ.1001

CLARREO Science Meeting July 2010 MGM: 5a- 5 IR Concept Consists of Electro-Optical and Calibration-Verification Modules Unique verification system quantifies calibration uncertainties

CLARREO Science Meeting July 2010 MGM: 5a- 6 Driving error terms defined Major Terms Driving Calibration Hot Calibration Blackbody Radiance Cold Calibration Blackbody Radiance FTS Error Terms Signal Gain Term Measurement equation converts sensor output signals into calibrated scene radiance Thermometry Space View Used On-Orbit – Not a Significant Contributor Uncertainty in Linearity Correction FTS Instrument Temperature Changes Between Calibrations Error Drivers Target Radiance

CLARREO Science Meeting July 2010 MGM: 5a- 7 Methodology for Measuring Spectral Radiance Measure spectral radiance with quantified uncertainties Emissivity Temperature SI Traceable Fixed Points Provide Known Temperature with Known Uncertainty Compare to NIST BBs Enabling SI Traceable measurements of absolute spectral radiance, spectral emissivity and temperature of Blackbody sources NIST Approaches for Emissivity Determination Paint and Cavity Reflectivity Measurements Monte Carlo Modeling NIST Approach for Temp Sensor Calibration Planck Equation NIST’s Advanced Infrared Radiometry and Imaging (AIRI) Facility - IR Spectral Radiance and Radiance Temperature at Ambient Conditions

CLARREO Science Meeting July 2010 MGM: 5a- 8 Maintaining Accuracy On-Orbit On-orbit, SI traceable measurements of temperature and emissivity High accuracy determination of the time-dependent bias is critical to creating trusted, enduring climate records. Traditional Approach: Space-based measurements of emitted thermal radiances are determined using blackbodies that have been well-characterized on the ground. The dominant sources of uncertainties include those in the BB cavity temperature and emissivity. Challenge: On-orbit sensors generally change/degrade over time. -- Temperature sensors and electronics drift -- BB surface coatings are known to change after extended exposure to LEO environment (e.g., atomic oxygen, outgassing) Solution: SI traceable measurements that quantify the BB T and  on-orbit

CLARREO Science Meeting July 2010 MGM: 5a- 9 On-Orbit Verification SI Traceability: Unbroken chain of comparisons with stated uncertainties Emissivity Temperature 3 Phase Change Cells Provide SI Traceable Fixed Points (-40 o C, 0 o C, 30 o C) Cavity Emissivity Measurement SI (Kelvin)-Based IR Radiance Scale Realization Quantum Cascade Laser (QCL) Heated Baffle Phase Change Cells Melt Material Planck Equation

CLARREO Science Meeting July 2010 MGM: 5a- 10 Verification System Overview

CLARREO Science Meeting July 2010 MGM: 5a- 11 Three initial and independent studies of FTS instruments show that the CLARREO accuracy requirements can be met –University of Wisconsin/Harvard University analysis indicates CLARREO accuracy requirement (total combined uncertainty) will be met over full spectrum –Analysis by Space Dynamics Lab (SDL) indicates requirement will be met at wavelengths > ~ 5.5  m (280K scene)  Calibration Equation used to quantify > 40 contributors to total uncertainty »Major contributors identified and tolerances assigned »Risk factors identified and mitigation plan prepared –Current analysis at Langley for CLARREO design also indicates requirement can be met Can L1 Accuracy Requirement be Met?

CLARREO Science Meeting July 2010 MGM: 5a- 12 IR Instrument Meets Level 1 Requirements Meet level 1 & level 2 requirements Combined Type B Uncertainty 54 mK Combined Type B Uncertainty 54 mK Calibration Blackbody Radiance 31 mK Calibration Blackbody Radiance 31 mK Space View Radiance < 1 mK Space View Radiance < 1 mK Gain Nonlinearity 29 mK Gain Nonlinearity 29 mK FTS Uncertainty Terms 33 mK FTS Uncertainty Terms 33 mK Estimated k=3 uncertainties at 1000 cm -1 for scene temperature of 250K, with calibration BB at 270K IR Level 1 Requirement 100 mK, 3  (k=3) Annual Type A Uncertainty < 1 mK Annual Type A Uncertainty < 1 mK Total Combined Uncertainty 54 mK SI Traceability: Unbroken chain of comparisons with stated uncertainties

CLARREO Science Meeting July 2010 MGM: 5a- 13 CLARREO, with its climate focus, looks to generate accurate radiances on annual to semi-annual time scales, on global average –Random uncertainty is present as noise on the measured radiance –Random uncertainty is reduced by averaging  More than 2 x 10 6 spectra per year reduce random uncertainty by ~ 1440 IR FTS noise is dependent on detector type (Pyroelectric vs. Solid State) Prior analyses indicated single spectrum noise: 0.05 K < NeDT < 10 K –Annual average uncertainty due to random noise: mK to 7 mK Random noise substantially impacts time to calibrate on ground and in-orbit Examined current off-the-shelf pyroelectric devices to verify performance Random Measurement Uncertainty Random uncertainty is not a science concern

14 Acquired 15 pyroelectric detectors from SELEX and their Specifications: IR waveband range: 15 to 50-micrometer for CLARREO Far-IR Material: DLATGS (Deuterated L-alanine doped Triglycine Sulfate) Operating temperature: ~300K Element active area: 3 mm Window: CsI Frequency range of operation: 10 Hz to 1 KHz Type Number: P5504 (5) Detectivity: 4.5x10 8 cm-Hz 1/2 100 Hz, 2.5x10 8 cm-Hz 1/2 1KHz Type Number: P5546 (5) Detectivity: 6x10 8 cm-Hz 1/2 100 Hz, 3.2x10 8 cm-Hz 1/2 Type Number: P5550 (5) Detectivity: 1.8x10 9 cm-Hz 1/2 Hz SELEX Pyroelectric Detector Characterization

15 Detector Temperature: 20 o C Detector/Monochromator with N 2 Purge Vendor Specifications (Spec.): Frequency:10 Hz D*: 25.0×10 8 Jones Note: This is beginning of life performance. We are looking into flight performance of similar pyroelectrics to estimate end of life performance SELEX P DLATGS Pyroelectric Detector Detectivity variation with Chopper Frequency SELEX Pyroelectric D* Calculations

16 Selected Four SELEX Pyroelectric Detectors SELEX Pyroelectric D* Summary

17 NEdT Comparison of SELEX DLATGS and Old Pyroelectric (200 cm-1 to 700 cm-1 with 25 cm-1 interval, Scene Temperature: 250K) SELEX Detectors: D* (P ): 1.296× ×10 8 D* (P ): 1.62× ×10 8 Old Pyroelectric Detector: D*: 2.5× ×10 8 NeDT Comparison, SELEX and Prior Pyro

18 Detector NER Summary

19 Detector NeDT Summary

20 Total Radiance Uncertainty by Detector and Scene

21 Total Error (T B ) by Detector and Scene Third Independent Study Supports CLARREO IR can meet Accuracy Reqm’t.

CLARREO Science Meeting July 2010 MGM: 5a- 22 Radiometric Modeling Status Testing at Langley and GSFC of SELEX pyroelectrics will continue Devices tested at Langley show much improved far-IR noise performance than previously calculated with data from SELEX catalog –Maximum NeDT is ~ 2 K vs. ~ 15 K at 200 cm -1 previous Three separate modeling efforts (UW; SDL; LaRC) all indicate CLARREO systematic error requirement (0.1 K, k = 3) can be achieved Integrated Product Team (selection coming soon) will continue to refine and update radiometric model to further guide instrument development

CLARREO Science Meeting July 2010 MGM: 5a- 23 Instrument Mass, Power, Thermal

CLARREO Science Meeting July 2010 MGM: 5a- 24 IR Instrument Suite Instrument suite is of moderate size and complexity QCL Radiator Metrology Laser Radiator IR Bench Radiator Cryo-Cooler Radiator Blackbody Radiator IR Scene Select Assembly IR FTS Scan Mechanism Cryo-Cooler Mid IR Detector Optical Assembly IR Instrument Mount Far IR Detector Optical Assembly IR Instrument Mount Verification Assembly

CLARREO Science Meeting July 2010 MGM: 5a- 25 IR suite is moderate class Infrared Instrument Comparison ClassInstrument Mass (kg) Pwr (W) Vol (m 3 ) Spectral Band Spectral Rsltn (cm -1 ) Absolute Accuracy (K) IFOV (km); Swath Width (km) Detector Format Explorer IRIS  m ~110 km Single element CIRS  m N/A Detector array ACE  m Solar occult Single element CLARREO IR Suite* – 50  m K (k=3) 25 nadir only Three single- element Sounders CrIS – 15  m K 14 +/ element array AIRS (Grating) – 15  m K / element array IASI – 15  m K 12 +/ Single element * Values reflect results of “DAC-5” activity to become compatible with Falcon 1-e

26 Vital Stats as of 5/2010 –Mass: 85 kg –Power: 152 W Falcon 1-e accommodation requires –Mass target: 80 kg –Power target: 140 W Held IDC session to evaluate alternate instrument configuration –Identify driving requirements and evaluate impact (e.g., risk, science) and benefit (e.g., mass, power, cost reduction) of relaxing the requirement Task: Develop IR Compatible with Falcon 1-e

27 Modified or no fore-optics Smaller blackbodies (emissivity vs. size) No dedicated instrument controller (i.e., use s/c processor) Reduce spectral range Reduce mid-IR detectors from 2 to 1 Reduce measurement requirements (e.g., resolution, accuracy, etc.) Methods for reducing and handling non-linearity Reduce temperature stability/control requirements Operation of verification system when excess power is available Use of composite materials Data rate reduction with compression IDC Potential Trades

28 Use more “evolved” instrument design Breadboard-like design, with smaller volume and surface area Reduced cooling requirements and power Update mass in cooling system hardware Mass change: kg Heater Power change: W Volume: m 3 (Prior 0.49 m 3 ) Instrument Geometry Trade

29 CLARREO IR Instrument Assembly, 05/01/ m 0.76 m 0.65 m Nadir Zenith Volume m³ LaRC Optic Design, Four Port FTS, Pupil Image and Winston Cone Combined System Breadboard Version IR Instrument Configuration

30 Knowledge of system response non-linearity in observed scene temperatures on orbit required More than 98% of earth scenes are between -70C and +50C Have cold calibration via space view below -70C Reduce cooling requirement (DAC4: -80C) to -70C Little impact (-1W) in reducing high (+50C) temperature; retain this for complete non-linearity verification Heater Power change: - 8W Verification Blackbody Temperature

31 Analysis: Mid-IR MCT detectors with similar spectral ranges and sensitivities –BAE (AIRS-LITE) operates at 60K –Teledyne (CrIS) operates at 80K Change to higher temperature (80K) Teledyne HgCdTe over prior baselined BAE AIRS-LITE 60K cryocooler temperature No change in science performance Cryocooler power change: W Mid-IR Cryocooler Temperature

32 Details now available concerning components sketched out in prior design cycles Determined specific component and board masses and powers Assumed cabling is 7% of final instrument mass Separate survival board electronics removed –Function to be provided by s/c Mass Change: kg Power Change: - 7.7W Refined Electronics Hardware Definitions

33 Reviewed MEL in detail to identify areas in need of additional refinement –FTS Assembly and Scanner: kg –Scene Select Components: kg –Thermal Control (Heat Pipes): kg MEL Scrub

34 Implemented the following changes –Instrument form factor changed –Raised minimum verification blackbody temperature to -70C –Changed mid-IR detector (increased operating temperature) –Refined MEL definition Results –Mass Change: kg (- 5 kg target) –Power Change: W  DC-DC converter power reductions with this change: W –Total Power Change: W (- 18 W target) Current IR Instrument: 76 kg, 124 W Current IR Instrument fits well within envelope for Falcon 1-e “Falcon 1-e” Summary

35 NASA has funded, via Instrument Incubator, Advanced Component Technology, and Advanced Technology Initiatives several projects since 2001 These have addressed fundamental needs for CLARREO IR instrument –FTS Technology –Verification system –Calibration –Component hardware –Detector technology Technology Development Status

36 NASA Technology Investments in CLARREO IR IIP 2001: FIRST –FTS; Focal planes; Beamsplitters; Far-IR science IIP 2004: INFLAME –FTS; Calibration; IIP 2007: CORSAIR –Beamsplitters, Blackbodies, Detectors IIP 2007: AASI –Blackbodies; Phase Change Cells; QCL; Verification system ACT 2008: FIREBIB –Far-IR detectors and Calibration ATI 2008: Melt Cell –Testing of Wisconsin and Utah State/SDL melt cells on the ISS –First launch in January 2011

CLARREO Science Meeting July 2010 MGM: 5a- 37 LaRC has developed technology for CLARREO for nearly one decade –FIRST and INFLAME FTS instruments developed and flown –CORSAIR, FIREBIB, Melt Cell projects in progress  Detectors, beamsplitters, blackbodies in development UW/Harvard developing CLARREO Technology –Verification system elements in development Key CLARREO technologies in development to TRL 6 Technology Development Heritage Melt Material Blackbodies Emissivity Monitoring Phase Change Cells QCL

CLARREO Science Meeting July 2010 MGM: 5a- 38 September – PWV = 0.75 mm 18

CLARREO Science Meeting July 2010 MGM: 5a- 39 September – PWV = 0.75 mm 19

CLARREO Science Meeting July 2010 MGM: 5a- 40 September – PWV = 0.4 mm 20

CLARREO Science Meeting July 2010 MGM: 5a- 41 IIPs and Breadboard Provide Early Risk Reduction Technology Development Plan Leverages Hardware Matured Through Breadboard and IIP Programs

CLARREO Science Meeting July 2010 MGM: 5a- 42 Technology Assessment ItemTRLStatus Calibration and Verification Module 4 Developed as part of the University of Wisconsin (UW) & Harvard (HU) and Space Dynamics Laboratory IIPs. Verification and Calibration Blackbody 4 Developed as part of the UW & HU IIP. Phase change cells, thermometry, and emissivity monitor are the pacing items. Scene Select Assembly 6 Standard technology; design will be configured and tested for CLARREO. Integrating Sphere 6 Standard technology; design will be configured and tested for CLARREO. Structure 6 Standard technology; design will be configured and tested for CLARREO. Reflects Current TRL Assessment Expect TRL-6 at Completion of IIP

CLARREO Science Meeting July 2010 MGM: 5a- 43 Technology Assessment ItemTRLStatus Electro-Optical Module 4 Pacing items are the Quantum Cascade Laser and beam- splitter. FTS Assembly 4 Coating spots on beam-splitter for reference laser -unknown TRL Mid-IR Assembly 5 The detector assembly is comprised of two single-element detectors, MCT and InSb, sharing a pupil image. Far-IR Assembly 6 Far-IR: baseline of a pyroelectric detector system is a configuration of high TRL parts not yet selected and tested for CLARREO. Selex pyros have flown on TES and Mini-TES Optical Bench 6 Standard Al honeycomb technology. Quantum Cascade Laser 4 Laboratory QCLs are available from several vendors and low power QCLs have been flight qualified on SAM. Fore-Optics 6 Standard optical components. Structure 6 Not a new technology, have flown before. Design will be tailored for CLARREO; standard practice. Radiator 6 Not a new technology, have flown before. Design will be tailored for CLARREO; standard practice. Electronics Module 6 Electronics 6 Mostly standard electronics design with high TRL components Reflects Current TRL Assessment Expect TRL-6 at Completion of IIP

NIST-CLARREO (IR-Instrument) Partnership - Activities Funded in Next Few Months - 1. QCL Laser (23  m) will be purchased this summer. The laser will be used to measure the BRDF of various candidate surface treatments. It will also be used for Reflectometry measurements in CHILR to measure reflections (emissivity) of actual assembled blackbodies 2. STEEP-3 Emissivity Modeling Software will be upgraded to incorporate BRDF for better blackbody modeling and design prior to construction. BRDF Integrating Sphere

CLARREO Calibration Facility Requirements - Activities Under Consideration for Phase A - CHILR Investments: Complete Hemispherical IR Laser Reflectometer will provide necessary data to the blackbody designers in order to develop high-fidelity models of emitting surfaces at wavelengths beyond ~15  m. Currently, there are no facilities that can acquire this data. These data will be fed back into the STEEP-3 upgrade as actual working parameters. CBS3 Investments: The Controlled Background Spectroradiometry and Spectrophotometer System will serve as NIST’s premier calibration facility for high accuracy (15 mK at 10  m / 300 K k = 2) investigations of blackbodies and detectors in the near to far IR (Range of operation: 1  m to 100  m, 190K to 350 K) This will provide absolute radiometric calibrations of the CLARREO flight blackbodies with high accuracy and confidence CHILR CBS 3 Cavity Integrating sphere Detector Sphere rotation & X-Y stage 23 µm 10.6µm

46 Climate Absolute Radiance and Refractivity Observatory (CLARREO) IR Instrument Phase A Trades

47 T1: Operating Temperature and Control T2: Optical Alignment Sensitivity T3: Detector Frequency Response T4: Temperature Measurement Electronics T5: Linearity Potential Trades discussed on following charts List of Potential Phase-A Trades

48 Operating temperature, thermal control, and thermal knowledge –Examines the trade between accurately measuring changes in temperature, reducing sensitivity to temperature changes by reducing the operating temperature, and the difficulty in controlling temperature at different operating temperatures. –Includes scene select mirror and baffles, fore optics and baffles, temperature difference between beamsplitter and compensator, and internal reference blackbody source. T1: Operating Temperature and Control

49 Optical alignment Sensitivity –Examine the ability of the optical path (including input and output optical axes, the beamsplitter and corner cube mounts, and FTS scan mechanism) to maintain shear alignment over the 15s calibration cycle. –Derive tolerance for changes in temperature gradients in the optical bench over the calibration period. T2: Optical Alignment

50 –Examine the trade between leveling the frequency response of the pyroelectric detector (by boosting gain for high frequency?), maintaining well-behaved group delay in the signal chain, and maintaining velocity reproducibility in the FTS scan mechanism. –Right now the fact that the pyroelectric response decreases so rapidly with frequency means that slight changes in FTS scan velocity give significant changes in responsivity and decrease calibration accuracy. T3: Detector Frequency Response

51 Electronics trade to evaluate best sensors for measuring absolute temperature (used primarily for calibration and verification sources) vs. best sensors for measuring small relative changes in temperature where you don't really care so much about the absolute temperature. Suspect that this means using a very linear temperature sensor; otherwise you need to know the temperature to get the temperature difference. There are places like the reference source where we need to measure changes in temperature over 15s to significantly better than 10 mK, but don't really need to know the absolute temperature. T4: Temperature Measurement Electronics

52 Electronics linearity knowledge and stability. –Sensitivity analysis to see if detector signal processing chain, detector through preamp and ADC to bits, can be linearized to better than 3e-5 (1> sigma) and if the electronics gain can be kept stable over 15s to better than 0.01%. T5: Linearity

CLARREO Science Meeting July 2010 MGM: 5a- 53 Thermometry – –Challenging radiometric accuracy requirements (0.1 K, k = 3) result in stringent accuracy of temperature measurements in the entire IR system –Addressing requirements through instrument modeling, –Temperature metrology labs (e.g., Langley, UW, SDL) are characterizing thermistor and PRT performance Radiometry – sources for calibration across the spectrum –Verifying accuracy of radiometric sources continue to be an issue –Continuing to work with NIST –Mlynczak to visit PTB/Berlin (NIST for Germany) July 19 –Will view their far-IR and Thz synchrotron sources for possible applicability to CLARREO Issues and Concerns

CLARREO Science Meeting July 2010 MGM: 5a- 54 IR Instrument Suite Concept meets the science objectives and is feasible –Instrument –Calibration (preflight and on orbit) Instrument design concept is viable –Uncertainty budget is defined and continually being updated –Key trade studies have been completed; Others defined for Phase A Plans to mature technologies are in place –IIPs –Breadboard under development Engaged fully with NIST Fully experienced team is (pending IPT and SDT selection) in place and ready to begin Phase A Ready to proceed into Phase A IR Summary & Status

CLARREO Science Meeting July 2010 MGM: 5a- 55 Backup Material

CLARREO Science Meeting July 2010 MGM: 5a- 56 Verification System Overview Check systematic errors on-orbit  Calibrated Earth spectra L(ν) and total systematic uncertainty are derived from observed spectra S E using calibration equation, Ambient BB (L HBB ; S H ) and Deep Space (L CBB ; S C )  Total Systematic Uncertainty estimate validated with Verification System: Verification Blackbody Integrating sphere with monochromatic (QCL) source  Verification blackbody checked with: Phase change cells to recalibrate temperature sensors Emissivity monitor and QCL to check cavity emissivity Off-zenith view to check for polarization effects  Vary temperature of verification BB to check nonlinearity

57 Grating Monochromater from Optronics Lab Spectral Range: 250 nm to 30-  m Calibrated Detectors: InGaAs (1- to 2.6-  m), PbS (1- to 3.2-  m), and Pyroelectric Detector (1- to 30-  m) Fourier Transform Spectrometer Nicolet 6700 FT-IR Spectrometer from Thermo Fisher Scientific Spectral Range: UV – Far IR (0.25- to 200-  m, or 40,000 to 50 cm-1) Beam Splitters: CaF2, KBr, and Polyethylene (Solid Substrate) Detectors: DTGS (CaF2 and KBr) and DTGS (Polyethylene-Solid Substrate) Sample Compartment: Internal Beam-splitter and Filter Characterization TOM (Tabletop Optical Module) Box: External Detector Charaterization Detector Characterization at Langley