1.0 INTRODUCTION/BACKGROUND: THE CORSAIR PROJECT HAS BEEN ESTABLISHED TO PROVIDE FAR-INFRARED BLACKBODY CAL…

Public award description

1.0 INTRODUCTION/BACKGROUND: THE CORSAIR PROJECT HAS BEEN ESTABLISHED TO PROVIDE FAR-INFRARED BLACKBODY CALIBRATION SOURCE STANDARDS BEYOND 15 MICROMETERS IN WAVELENGTH (I.E., THE SPECTRAL REGION REFERRED TO AS THE FAR INFRARED) FOR THE FUTURE NATIONAL AERONAUTICS AND SPACE ADMINISTRATION (NASA) CLIMATE ABSOLUTE RADIANCE AND REFRACTIVITY OBSERVATORY (CLARREO) MISSION DEFINED BY THE RECENT DECADAL SURVEY FOR EARTH SCIENCE. THE CLARREO MISSION WILL MAKE MEASUREMENTS OF EARTH'S EMITTED SPECTRAL INFRARED RADIANCE (W CM-2 SR CM-1) AT UNPRECEDENTED ACCURACY FOR THE PURPOSES OF DETECTING AND ATTRIBUTING CLIMATE CHANGE. TO ACHIEVE THE REQUIRED ACCURACY ON CLARREO, NEW TECHNOLOGIES MUST BE DEVELOPED AND DEMONSTRATED THAT WILL ENABLE ACCURATE AND CONTINUOUS ON-BOARD CALIBRATION OF THE CLARREO INFRARED SPECTROMETERS. UNDER THE CORSAIR PROJECT NEW RADIOMETRIC STANDARDS WILL BE DEVELOPED USING TECHNIQUES TO ACCURATELY DETERMINE THE TEMPERATURE OF THE CALIBRATION SOURCES THAT ARE TIED TO THE INTERNATIONAL SYSTEM (SYST ME INTERNATIONAL OR SI) OF STANDARDS. THESE STANDARDS AND TECHNIQUES WILL BE USED IN THE CORSAIR PROJECT TO DEVELOP A PROTOTYPE A CALIBRATION STANDARD BLACKBODY APPLICABLE TO USE IN ORBITING INFRARED SENSORS. INFRARED ORBITING SENSORS ARE CALIBRATED IN PART BY MEANS OF OBSERVING ON-BOARD RADIANCE SOURCES CALLED BLACKBODIES. THE RADIANCE EMITTED FROM A PERFECT BLACKBODY IS A FUNCTION ONLY OF ITS TEMPERATURE. THE RADIANCE EMITTED BY A REAL BLACKBODY IS A FUNCTION OF BOTH ITS TEMPERATURE AND EMISSIVITY. FOR ACCURATE CALIBRATION OF AN ORBITING SENSOR BOTH THE TEMPERATURE AND THE EMISSIVITY OF THE CALIBRATION BLACKBODY MUST BE KNOWN EXCEPTIONALLY WELL. A STANDARD APPROACH TO MEASURING THE TEMPERATURE OF A BLACKBODY IS TO RELY ON CALIBRATED TEMPERATURE SENSORS (PLATINUM RESISTANCE THERMOMETERS AND THERMISTORS) TO MEASURE THE BLACKBODY CAVITY TEMPERATURE. THESE TEMPERATURE SENSORS CAN BE CALIBRATED TO THE ~12 MK (2σ) (1 MK = 0.001 KELVIN) LEVEL IN THE LABORATORY, BUT THE CALIBRATION CAN CHANGE DUE TO HANDLING OR USE. IN LABORATORY USE, THESE TEMPERATURE SENSORS ARE GENERALLY RECALIBRATED WITHIN A YEAR, BUT THERE IS CURRENTLY NO WAY TO RECALIBRATE TEMPERATURE SENSORS ON ORBIT. THE CAVITY THERMISTOR APPROACH IS NOT SUFFICIENT TO ASSURE THE CLARREO CALIBRATION REQUIREMENTS. TECHNIQUES TO ACCURATELY MEASURE THE BLACKBODY TEMPERATURE, TRACEABLE TO INTERNATIONAL STANDARDS, WILL BE DEVELOPED AS PART OF THE CORSAIR EFFORT. THE EMISSIVITY OF A BLACKBODY IS MADE AS CLOSE TO UNITY (1.0) AS POSSIBLE THROUGH THE SELECTION OF PAINT FOR THE BLACKBODY CAVITY THAT IS HIGHLY ABSORPTIVE OVER ALL WAVELENGTHS. HIGHLY EMISSIVE BLACKBODIES FOR MID-INFRARED SENSORS GENERALLY USE A DESIGN BASED ON A DIFFUSELY SCATTERING SURFACE. IN THE FAR-INFRARED MOST MATERIALS BECOME SPECULAR, REDUCING THE EFFECTIVENESS OF THESE DESIGNS. UNDER PRIOR NASA FUNDING, A TEAM COMPOSED OF NASA, SPACE DYNAMICS LABORATORY (SDL), AND THE HARVARD-SMITHSONIAN CENTER FOR ASTROPHYSICS DEVELOPED THE FAR-INFRARED SPECTROSCOPY OF THE TROPOSPHERE (FIRST) INSTRUMENT [MLYNCZAK ET AL., 2006]. FOR FIRST, SDL DEVELOPED BLACKBODIES THAT USED A SPECULAR DESIGN WITH SPECULAR PAINT. BASED ON THE MEASURED PAINT EMISSIVITY AND A CAVITY MODEL, THESE BLACKBODIES HAVE AN EMISSIVITY OF 0.999 OR BETTER OVER THE 10 TO 100 MICROMETERS RANGE. THERE IS AT PRESENT NO WAY TO MONITOR THE EMISSIVITY IN A BLACKBODY ON ORBIT. EMISSIVITY CHANGES IN ON THE ORDER OF 3 PARTS IN 10,000 WILL ADD SIGNIFICANTLY TO THE ERROR BUDGET. TECHNIQUES TO MONITOR CHANGES IN THE BLACKBODY EMISSIVITY THAT CAN BE USED WHILE IN ORBIT ARE REQUIRED AND WILL BE DEVELOPED AS PART OF THE CORSAIR EFFORT. THIS STATEMENT OF WORK (SOW) DETAILS A 3-YEAR PROGRAM FOR DEVELOPING AND DEMONSTRATING TECHNOLOGIES WITH A GOAL OF REALIZING A PROTOTYPE BLACKBODY WHOSE TEMPERATURE IS TRACEABLE TO INTERNATIONAL STANDARDS ON ORBIT AND WHOSE EMISSIVITY CAN BE ACCURATELY MONITORED ON ORBIT. THE PROTOTYPE SHALL BE DIRECTLY A