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CLARREO UW & Harvard Team Proposed IIP Activities (with description of underlying research)

CLARREO UW & Harvard Team Proposed IIP Activities (with description of underlying research). Fred Best. University of Wisconsin. CLARREO Meeting at NIST 12 June, 2008. Topics. CLARREO IIP Scope Proposed IIP Technologies with Background Development Summary

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CLARREO UW & Harvard Team Proposed IIP Activities (with description of underlying research)

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  1. CLARREOUW & Harvard TeamProposed IIP Activities(with description of underlying research) Fred Best University of Wisconsin CLARREO Meeting at NIST 12 June, 2008

  2. Topics • CLARREO IIP Scope • Proposed IIP Technologies with Background Development Summary • On-orbit Absolute Radiance Standard (OARS) • On-orbit Cavity Emissivity Module (OCEM) • On-orbit Spectral Response Module (OSRM) • Dual Absolute Radiance Interferometers (DARI) • TRL Progressions and Program Milestones CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  3. A New Class of Advanced Accuracy Satellite Instrumentation (AASI) for the CLARREO Mission • The objective of the proposed IIP work is to develop and demonstrate the technologies necessary to measure IR spectrally resolved radiances with ultra high accuracy (< 0.1 K 3-sigma brightness temperature at scene temperature) for the CLARREO benchmark climate mission. CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  4. CLARREO Radiometric Performance • Estimated 3-sigma calibrated brightness temperature uncertainty shown as a function of scene brightness temperature, based on use of the AASI. The uncertainty of the blackbody radiating temperature (45 mK, 3-sigma) dominates, except for large wavenumbers at cold temperatures where the assumed telescope temperature change of 20 mK between earth and calibration views becomes important. We assumed an emissivity of 0.999 with 0.0006 uncertainty and a blackbody temperature of 300 K, while the instrument is at 285 K. CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  5. CLARREO Viewing Configuration Developed under this IIP • Viewing configuration providing immunity to polarization effects. CLARREO FTS Scene Mirror Provides Earth and Space Views as well as Views to Targets Involving Technologies Developed Under this IIP, That Give Unprecedented Absolute Calibration Accuracy on-orbit. CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  6. Proposed Technologies (OARS) • On-orbit Absolute Radiance Standard (OARS) that uses multiple phase change material signatures to establish absolute temperature knowledge to 10 mK throughout the lifetime of the satellite. The OARS is a source that will be used to maintain SI traceability of the radiance spectra measured by separately calibrated dual interferometer sensors. CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  7. UW-SSEC Developed GIFTS EDU BlackbodyPerformance Significantly Exceeds Specifications GIFTS Engineering Development Unit Blackbody Controller Card Blackbody (2) 1” Cavity Aperture Specification As Delivered Key Parameter Thermofoil Heater Aluminum Enclosure Aluminum Cavity Thermistor Temperature Sensors Support Tube/ Thermal Isolator CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  8. GIFTS Blackbody 1” Cavity Aperture Aluminum Enclosure Aluminum Cavity Thermofoil Heater Cavity Surface Aeroglaze Z306 Thermistor Assemblies (5) Glass-filled Noryl Cavity Support Tube / Thermal Isolator Mechanical Support for Enclosure Glass-filled Noryl Base Base Thermistor CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  9. A new approachcompared to the traditional laboratory approach Blackbody Cavity A Temperature Probe A Heater • View AA - • (expanded) Blackbody Cavity Melt Materials (3 different) Outer insulation not shown Fixed Point Reference Material Melt Material Temperature Sensors (3) Temperature Controlled Bath Traditional Laboratory Calibration Scheme Melt Signature Configuration (based on long-term thermal stability at melt temperatuere) (based on temperature signature while transitioning through melt temperature) CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  10. Question • Can a melt material mass of < 1/1000th of the cavity mass give the accuracy needed for CLARREO? • YES! CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  11. Anatomy of a Melt Signature Cavity response if no melt material present With melt complete, cavity temperature rises Temperature melt plateau When Ga melt material is present, the added power goes into changing the phase to liquid - no cavity temperature rise. Time Cavity held at constant temperature Constant ∆Power Applied Ga Melt CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  12. SSEC Engineering Test Cavity(configured for melt tests) 1 cm Thermistor Melt Material Thermistor potted into custom housing then threaded into aluminum cavity. 0.38 g of Ga melt material placed into thermistor housing modified with stainless steel sleeve and nylon plug. Blackbody Cavity CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  13. Gallium Melt Repeatability 20 mK Zoom view • Ramps with similar melt times match very closely • Ramp 66 was 8 months after other ramps • Ramps 38 and 41 were done inside the chamber; the rest outside CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  14. Melt Time Comparisons CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  15. Longer Melt Time = Better Accuracy 20 mK * * Asymptote of Model Fit is within 1mK of Ga Melt Point Ga Melt CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  16. Cavity Gradient Very Low During Melt Circumferential Heater Aluminum Blackbody Cavity - (HBB-B HBB-A) Thermistor HBB-B Ga Melt Material Thermistor HBB-A 1.2 mK ∆ Temp. ( C) Temperature gradient between spatially separated temperature sensors only ~1.2mK, even during “fast” 4800 sec. melt. CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  17. Thermal Modeling A thermal model was developed and tuned to agree with test data, and then used to: • Explore relationships between important system parameters and melt behavior. • Heat leak effects due to cabling. • Mass and aspect ratio of melt material. • Ramp Power. • Thermal Resistance between melt material and cavity. • Thermal Resistance between thermistor and melt material. • Explore and predict the impact of variations in the external temperature environment on Melt Signatures. • Predict and optimize melt signature behavior of different materials. Axisymmetric Thermal Model CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  18. Measured Melt Signatures(using GIFTS BB Configuration) -40 °C -20 °C 0 °C 20 °C 40 °C -38.87 °C Mercury 0.00 °C Water 29.77 °C Gallium Mercury Melt (test data) Water Melt (test data) Gallium Melt (test data) Approach Exponential Fit Mercury Melt = -38.87 °C Temperature [°C] Water Melt = 0 °C Gallium Melt = 29.765 °C Thermistor Temperature Thermistor Temperature Thermistor Temperature Time [s] Melt Signatures Provide Absolute Temperature Calibration Accuracies Better Than 10 mK CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  19. Implementation for CLARREO(GIFTS Blackbody Embodiment) • Small quantities of Water, Gallium, Mercury, and possibly more materials are imbedded in the blackbody cavity, providing three or more known temperature reference points. • The thermistors will be interleaved in the cavity between these reference materials. • Temperature calibration points are established by sequentially passing through the melt plateaus of the reference materials. • During the melt plateaus, the thermistor resistances corresponding to the phase change points are measured. • The thermistors are fully characterized over the entire range of temperatures represented by the three (or more) reference materials, by using the traditionally obtained Steinhart & Hart Coefficients. CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  20. Benefits of This Novel Approach • Absolute temperature calibration is provided on-orbit on-demand. • Scheme provides temperature calibration of all the blackbody cavity thermistor sensors, over a significant temperature range – allowing normal blackbody operation at any temperature within this range. • Concept is simple and requires very little mass. • Implementation requires straight-forward modification of an existing flight hardware design (GIFTS). • Very high accuracy is obtained – each temperature calibration point associated with a melt material can be established to well within 10 mK, and more accuracy is obtainable with longer melt times. CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  21. IIP Focus for OARS • Optimize Containment System used for the Miniature Phase Change Cells. • Surface Tension dominating Gravitational effects. • Melt signature enhancement. • Containment and Melt Material Compatibility. • Melt contamination from Dissolution • Liquid Metal Embrittlement of containment system • Demonstrate performance after accelerated life testing to simulating full mission lifetime. • Optimize melt algorithm refinements. • Refine thermal modeling. CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  22. Proposed Technologies (OCEM) • On-orbit Cavity Emissivity Module (OCEM) that directly determines the on-axis emissivity of the OARS throughout the instrument lifetime on-orbit. Two versions will be developed: • one using a quantum cascade laser source (Harvard), and • one based on a heated halo source (Wisconsin). Harvard QCL Approach UW Heated Halo Approach CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  23. IIP Focus for OCEM • Quantum Cascade Laser Source OCEM (Harvard) • Optimize power coupling of the QCL to the infrared optical fiber. • Embed detectors directly into the blackbody cavity wall allowing a direct measurement of surface emissivity. • Conduct end-to-end Interferometer tests to determine cavity emissivity. • Heated Halo Source OCEM (Wisconsin) • Configure system to be integrated into the 1” OARS Blackbody. • Conduct end-to-end interferometer tests with OCEM to verify required noise performance and stability. CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  24. Proposed Technologies (OSRM) • On-orbit Spectral Response Module (OSRM) that uniquely determines the spectral instrument line shape of the interferometers over the lifetime of the instrument on-orbit. Signature of the instrument lineshape superimposed on a blackbody spectrum. The baseline spectrum is that of a room temperature blackbody. The monochromatic radiation from a QCL at 1263 cm-1 is directed into the cavity and the resulting spectrum resolved at 0.5 cm-1 reveals the spectrometer lineshape. CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  25. IIP Focus for OSRM • Develop OSRM Cavity with optimized diffuse reflectivity. • Develop appropriate stable QCL power driver allowing the long integration times needed to determine the ILS to the desired level of precision. • Conduct end-to-end interferometer testing to verify performance and stability. CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  26. Proposed Technologies (DARI) • Dual Absolute Radiance Interferometers (DARI) for measuring spectrally-resolved radiances over a major part of the thermal infrared spectral domain. Fourier Transform Spectrometer (FTS) systems with strong flight heritage will be configured for detailed performance testing and design trades as part of this IIP. • UW Focus - High Performance FTS • Harvard Focus - Far IR CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  27. DARI IIP Configurations & Focus CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  28. CLARREO IIP High Performance FTS Absolute Radiance Interferometer CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  29. CLARREO IIP Far IR FTS Absolute Radiance Interferometer CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  30. IIP High Performance FTS Subsystem - Key Elements The High Performance FTS subsystem to be developed by UW-SSEC will include an interferometer with diode laser-based metrology and multiple beamsplitter options (at least ZnSe and Si), a detector/dewar subassembly, and a small pulse-tube mechanical cooler, all chosen for their strong spaceflight heritage such that detailed performance testing can be conducted on a subsystem with a clear path to space. • FTS: GOSAT/TANSO ACE-FTS Hybrid adapted for Far IR • representative of flight model interferometer requirements • commercial ABB electronics. • Cooler: NGST Pulse Tube Microcooler • To minimize cost and schedule NGST will provide, on a temporary basis, a micro-compressor and tactical electronics while fabricating a coaxial cold head, reservoir tank and inertance line as part of the program. These subassemblies will be assembled and performance testing conducted to validate the cooler system operation. • Low power, low mass, low vibration, long life • Detector/Dewar Assembly • Single dewar • Cold-finger/bellows interface to cooler • Similar to existing UW-SSEC S-HIS detector/dewar subassembly • single cold field stop, refractive elements to focus the aperture stop onto the detectors • at least two semi-conductor detectors chosen for high linearity. CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  31. IIP Technology Advancement CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

  32. TRL Progression and Program Milestones CLARREO Meeting at NIST 12 June 2008 Proposed IIP Activities & Required NIST Capabilities for CLARREO

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