On-Orbit Absolute Radiance Standard for the Next Generation of IR Remote Sensing Instruments

Transcription

1 8 January 2011 On-Orbit Absolute Radiance Standard for the Next Generation of IR Remote Sensing Instruments Work Conducted Under a NASA IIP Fred A. Best, Henry E. Revercomb (PI), Douglas P. Adler, Claire Pettersen, P. Jonathan Gero, Joseph K. Taylor, Robert O. Knuteson University of Wisconsin Space Science and Engineering Center 2011 Workshop on Far-Infrared Remote Sensing 8-9 November 2011 Madison, WI

2 Topics On-Orbit Verification and Testing Motivation Required / Expected Performance OARS (On-orbit Absolute Radiance Standard) Temperature Calibration: Miniature Phase Change Cells Emissivity Measurement: Heated Halo Jon Gero Miniature Phase Change Cells Concept Focus of NASA IIP Accelerated Life Test Demonstration in Microgravity Integration to OARS and System-Level Testing with Absolute Radiance Interferometer

3 Introduction In the Infrared, decades of progress in calibrated FTIR brought us to this step Ground-based NIST Traceable Testing and Characterization Calibrated FTIR On-orbit Starting with Hanel IRIS, 1969 Groundbased/ Airborne Validation EOS: New Emphasis Slide 3

4 Introduction New developments for CLARREO under a NASA IIP provide a strong foundation for this step (TRL-6) Ground-based NIST Traceable Testing and Characterization CLARREO On-orbit Calibrated Verification FTIR and Testing On-orbit Groundbased/ Airborne Validation Slide 4

5 On-Orbit Verification and Test System OARS On-orbit Absolute Radiance Standard Includes Multiple Miniature Phase Change Cells for absolute temperature calibration and Heated Halo OCEM for spectral reflectance measurement Space View 2 Calibration Reference: Deep Space OSRM OSRM On-orbit Spectral Response Module Measures Instrument Lineshape OARS Calibration Reference: Ambient Blackbody Used in conjunction with Space View for instrument calibration Halo OCEM OCEM On-orbit Cavity Emissivity Module Heated Halo QCL Beamsplitter Polarization Axis Earth QCL used for QCL-OCEM and OSRM Slide 5

6 On-Orbit Verification and Test System OARS On-orbit Absolute Radiance Standard Includes Multiple Miniature Phase Change Cells for absolute temperature calibration and Heated Halo OCEM for spectral reflectance measurement Space View 2 Calibration Reference: Deep Space OSRM OSRM On-orbit Spectral Response Module Measures Instrument Lineshape OARS OARS Calibration Reference: Ambient Blackbody Used in conjunction with Space View for instrument calibration Halo OCEM OCEM On-orbit Cavity Emissivity Module Heated Halo QCL Beamsplitter Polarization Axis Earth QCL used for QCL-OCEM and OSRM Slide 6

7 Brightness T Error [k, 3 sigma] Brightness T 0.04 CLARREO Radiometric Performance Scene Temperature [K] cm cm cm cm K 3 measurement accuracy requirement Value Uncertainty Temperatures Calibrated FTS 290 K K ABB 295 K K OARS 220 to 320 K K ABB Emissivity Scene Temperature [K] OARS cm cm cm cm Calibrated FTS OARS 200 cm cm cm cm-1 The OARS emissivity is determined from T/V testing with a very high emissivity source. The independent uncertainties are root-sum-squared and the CFTS uncertainty includes a nonlinearity of 0.03% (after correction).

8 Cold Plate Outer Enclosure (MLI not shown) OARS Design Concept Based on GIFTS Blackbody Phase Change Cells (Ga, H 2 O, & Hg) Temperature Controlled Shroud (MLI not shown) Conductive Bridge Conductive Bridge Thermal Isolator Thermistors Temperature Controlled Cavity Heated Halo (Jon Gero Talk)

9 Temperature Calibration Using Miniature Phase Change Cells Miniature Phase Change Cell Concept Summary of IIP Work Slide 9

10 SSEC Engineering Test Cavity (GIFTS Style Blackbody configured for melt tests) Blackbody Cavity (aft view) 1 cm GIFTS Blackbody 1 Cavity Aperture Three or more will characterize the thermistor sensors Melt Material Thermistor Thermofoil Heater Cavity Surface Aeroglaze Z306 Aluminum Enclosure Aluminum Cavity Glass-filled Noryl Cavity Support Tube / Thermal Isolator Glass-filled Noryl Base view at top-left Thermistor Assemblies (5) Mechanical Support for Enclosure Base Thermistor Phase Change Material Implementation

11 Temperature Temperature (deg C) Anatomy of a Melt Signature Gallium - Ramp38 Match Ga Melt melt plateau No melt material present M N When Ga melt material is present, the added power goes into changing the phase to liquid - no cavity temperature rise. Cavity held at constant temperature Time Constant Power Applied Time (seconds) Slide 11

12 Signature Dependence on Melt Length Signatures are very repeatable 0.1K 0.01K Melt curves that are flatter and approach the theoretical melt temperature are obtained with longer melt times. Mid-melt temperature vs melt length relationship is stable and can be very well characterized. This was the technology brought into the NASA IIP for refinement Slide 12

13 Temperature [ C] Measured Melt Signatures (using GIFTS BB Configuration) -40 C -20 C 0 C 20 C 40 C C Mercury 0.00 C Water Ga-In C Gallium Mercury Melt (test data) Water Melt (test data) Gallium Melt (test data) Approach Exponential Fit Thermistor Temperature Mercury Melt = C Thermistor Temperature Water Melt = 0 C Thermistor Temperature Gallium Melt = C ,000 30,000 35,000 40,000 45,000 50, ,000 25,000 30,000 35,000 40,000 45,000 Time [s] ,000 10,000 15,000 20,000 25,000 Melt Signatures Provide Absolute Temperature Calibration Accuracies Better Than 10 mk Slide 13

14 End-to-end System Calibration Steinhart-Hart Relationship Traditional Steinhart-Hart Relationship T = 1 A + B ln(r) + C (ln(r)) 3 Establishing A, B, & C with three melt points: A B C = 1 ln R Ga (ln R Ga ) 3 1 ln R H2 O (ln R H 2 O) 3 1 ln R Hg (ln R Hg ) T Ga -1 T H 2 O -1 T Hg Slide 14

15 Benefits of This Novel Approach Absolute temperature calibration is provided on-orbit on-demand. 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. 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. Slide 15

16 Aluminum Areas of Focus For NASA IIP What do we have to do to make this technology more Flight-Ready? Material Compatibility The containment material must be inert to the (Ga, H 2 O, and Hg) phase change materials so that there will be no dissolution that can alter the melt temperature. In addition, the containment material must not be susceptible to Liquid Metal Embrittlement. Phase Change Material Sealing Techniques The phase change materials must be sealed in their housings with an inert gas. The seal must be designed for a differential pressures of one atmosphere, and for a temperature range from 180 to 330 K. Seal integrity must last 5 to 10 years. Zero-G Affects Aluminum Mechanical Stress Confinement geometry must allow Surface Tension forces to dominate Gravitational forces, in order for the characterizations and calibrations conducted under 1-G to transfer to the Zero-G environment. Stainless 1 cm Issues related to freezing expansion of Ga and H 2 O must be accounted for. Slide 16

17 Sealing Technology Welded Cap Laser Beam Laser Beam Tapered Plug (Stainless Steel) Fillet Weld Housing (Stainless Steel) Melt Material (Ga, H20, or Hg) Preco, Inc. precision laser welding 60 Watts 20 per minute* 20 off rotation axis µm level accuracy *0.9 seconds of power applied 0.15 sec. into weld 3.0 sec. into weld Thermal Model shows max water temp. during weld is <45 C, 3 sec. after initiation of weld. Slide 17

18 Full Accelerated Life Test Flow 900 full cycles (~-80 to +60 C) 12 days at +80 C Witness Sample Test Sample Melt Signature Tests Melt Signature Tests Rapid Full-Temperature Cycling Accelerated Life At Elevated Temperature Melt Signature Tests Housing Analysis SEM/EDS Melt Analysis TXRF Slide 18

19 SEM Inspection Methods Below Left Below Center Below Right Findings for Gallium No Gallium/LME present in the polished cross-section. No evidence of diffusion of Gallium microstructure. Small spots on inner surface are Gallium. Backscattered Electrons / EDS Secondary Electrons Inner Housing Cut Through Housing Circumferential*

20 SEM Investigation of Weld Zone Cap Cap Weld Zone Weld Zone Housing Housing Housing Cap Weld Zone

21 Summary of Phase Change Material Status Blackbody Configuration TEC Configuration Accelerated Life Configuration

22 Signatures in Blackbody Melt Approach Exponential Departure Exponential Linear Ramp Fit Miniature Phase Change Cells Integrated Into Blackbody and Signatures Obtained

23 Temp (C) Gallium Mid-Melt Temperature for Various Melt Lengths Pre FALT Post FALT Curve Fit 10 mk Melt Length (sec) Data is comprised of six different housings Pre and post-falt, and multiple orientations are included Two housings were run upside-down

24 Temp (C) Water Mid-Melt Temperature for Various Melt Lengths Pre FALT Post FALT Curve Fit Water MP (0.000) mk Melt Length (sec) Data is comprised of three different housings Pre and post-falt, and multiple orientations are included Housings were run in normal configuration and upside down

25 Temp (C) Mercury Mid-Melt Temperature for Various Melt Lengths Pre FALT Post FALT Curve Fit Hg MP ( ) 10 mk Melt Length (sec) Data is comprised of four different housings Pre and post-falt and multiple orientations are included Two housings were run on their sides

26 Demonstration in Microgravity Slide 26

27 UW-SSEC Phase Change Cell Demo on ISS Martin Mlynczak, PI; Shane Topham, SDL Lead UW-SSEC Multiple Phase Change Experiment SDL Experiment Support Package UW Lab Testing Utah State Space Dynamics Lab (SDL) has developed an ISS experiment for their single phase change cell demonstration. UW is developing a multiple phase change cell with three different phase change materials compatible with SDL hardware (Ga, GaSn, H 2 O) This will allow validation of this calibration approach in microgravity.

28 Temperature (C) Temperature (C) Temperature (C) Temperature (C) UW-SSEC Phase Change Cell Demo on ISS Melt Cycle Gallium-Tin Gallium Gallium Melt Gallium Water Time (sec) GaSn Melt Gallium-Tin Time (sec) Completed development of hardware optimized for low temperatures to ensure freezing of supercooling melt materials improved from -5C to -15C Obtained signatures with Water, Ga-In Eutectic, and Ga using UW electronics Tested and calibrated using SDL electronics End-to-end testing using SDL electronics Time (sec) Melt 0.4 Water Time (sec)

29 Temperature (C) Supercooling Statistics Samples were cycled from ~50C to -30C Freezes were recorded Cycles are post warm-soak 0-2 Water Freezes Water 1 Water 2 Water 3 TEC Limit Cycle Number Water with AgI froze above the TEC limits Did not seem to drift over time to lower freezes Slide 29

30 OARS Assembly and Integration to Absolute Radiance Interferometer Slide 30

31 OARS Design Based on GIFTS Blackbody (designed for operation in lab environment) Outer Enclosure Phase Change Cells (Ga, H 2 O, & Hg) Temperature Controlled Shroud Temperature Controlled Fluid For Shroud Fluid Thermal Isolator Thermistors Temperature Controlled Cavity Heated Halo (Jon Gero Talk)

32 OARS Cavity, Isolator, and Heated Halo Heated Halo Cavity 30 mm Phase Change Cell Thermal Isolator

33 OARS Cavity, Isolator, and Heated Halo Cavity Thermal Isolator Heated Halo Phase Change Cell

34 Thermistor Calibration

35 Phase Change Cell Thermistor

36 OARS Cavity and Thermal Isolator Thermistor Phase Change Cell Cavity Thermal Isolator Looking into Aft Of Cavity

37 OARS Assembly Heated Halo & Halo Insulator Cavity Inner Shield & Isolator Outer Case

38 ARI Breadboard Sky View HBB OARS ABB

39 ARI Breadboard Interferometer Modulator Wishbone Fore Optics Aft Optics Assembly

40 Conclusions Significant progress has been made toward the development of an Absolute Radiance Source that can be used on future IR Remote Sensing Instruments. The demanding performance parameters required for a CLARREO type mission are being demonstrated in a relevant environment. An upcoming demonstration in the microgravity environment of the ISS will be the last hurdle needed to qualify the design for a flight mission.

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