Cross Track Infrared Sounder (CrIS) Flight Model 1 Test Results

Transcription

1 May 6, 2009 Ronald Glumb, Joseph P. Predina, Robert Hookman, Chris Ellsworth, John Bobilya, Steve Wells, Lawrence Suwinski, Rebecca Frain, and Larry Crawford For Publication at the ASS-FTS14 Conference Cross Track Infrared Sounder (CrIS) Flight Model 1 Test Results

2 CrIS Mission: Provide Vertical Soundings of Temperature, Moisture and Pressure for NPOESS NPOESS National Polar-orbiting Operational Environmental Satellite System Convergence of POES and DMSP CrIS One of the Mission-Critical Payloads on NPOESS Part of the Crosstrack Infrared and Microwave Sensor Suite (CrIMSS) with ATMS Interferometric collection of highresolution infrared spectra Produces vertical profiles of temperature, moisture and pressure on a global basis NPOESS C1 Possible Addition to NPOESS C2 NPP May 6,

3 CrIS is Manifested on NPP and NPOESS NPOESS Spacecraft NPP Spacecraft May 6,

4 CrIS Mission: Construct Vertical Profiles of Temperature, Moisture, and Pressure (EDRs) CrIS ±50 Cross track Scans 1.25-Orbit Data Dump RDRs RDR = Raw Data Record SDR = Sensor Data Record EDR = Environmental Data Record 30 Earth Scenes 2,200 km Swath Central or Regional Ground Stations Decode Spacecraft Data Sensor Calibration Algorithms RDRs SDRs 3x3 Array of CrIS FOVs (Each at 14-km Diameter) EDR Algorithms Pressure (mb) EDRs Temperature (K) May 6,

5 CrIS Possesses 9 Instantaneous Fields of View Stepped Over 30 Earth Locations Every 8 Seconds 3.33 degree steps Single CrIS Scan Line (full sweep, 30 FORs) Nadir CrIS Field of Regard (FOR) Definition 1 FOR = 9 FOVs 1 FOV = 3 IR bands degree 1.1 degree (14.0 km) (16.0 km) degree 1100 km Anti-sun degree (16 km) S/C Velocity degree (14.0 km) Three Successive CrIS Scan Lines (nadir to edge sweep) May 6,

6 CrIS Is A Fourier Transform Spectrometer Covering 3 IR Bands With 1305 Spectral Channels Two Sided Interferograms LW MW SW OPD [cm] Wavenumber Range cm -1 Maximum OPD ±0.8 ±0.4 ±0.2 cm Spectral Resolution cm -1 Spectral Channels # May 6,

7 CrIS Instrument Physical Layout Electronics Scanner Instrument Structure and Optical Assemblies (Interferometer, Telescope, etc.) Passive Cooler for IR FPAs Vibration Isolation System May 6,

8 Partially Unfolded CrIS Optical System Shows Flow of Signal Radiance to Detectors Extremely Compact Large Aperture Excellent Image Quality Fully Wedged / Tilted Athermalized Design Pupil Imaging System FPA Detector Optics Interferometer Cooler Telescope Scene Radiance SSM May 6,

9 Eleven Modules Assemble To Form CrIS Sensor PCE & SSM: CrIS Super-Module: SSM DCM Processing Control Electronics (PCE less CCAs) Mechanical Subsystems: CrIS Earth Shield Telescope Aft Optics Optical Bench Instrument Frame Cover Isolation System ICT Interferometer May 6,

10 Comprehensive Test Facilities Supported Tests Precision Radiometric Targets TVAC Radiators ILS Gas Handling Active Cooler for Bench Tests Collimator / Gas Cell Data Acquisition Systems May 6,

11 CrIS Flight Model 1 (FM1) Testing Overview CrIS FM1 has successfully completed a comprehensive qualification and performance test program Vibration tests EMI tests Electrical Performance Field of View (FOV) Shape / Coregistration Instrument Line Shape (ILS) / Spectral Accuracy Noise Equivalent Spectral Radiance (NEdN) Long Term Repeatability Radiometric Uncertainty This presentation will focus on the Mission Nominal Thermal Vacuum Test results that best represent on orbit system performance May 6,

12 Overall FM1 Performance Is Outstanding Excellent NEdN performance, especially for expected on-orbit thermal conditions Radiometric trending data indicates a very stable instrument No statistically significant changes in coregistration alignment or FOV shapes throughout vibe and TVAC temperature range NEdN trending is very solid Excellent spectral accuracy performance Near-flawless electrical performance during tests No Can-Not-Duplicates or unexplained instrument resets Over 1 TB of FM1 data has been collected and analyzed All planned tests were successfully accomplished May 6,

13 Vibration Tests Highlight Exceptional Structural Stability No Shifts in Any Instrument Modes (Pre-Vibe to Post-Vibe) Structure is Extremely Stable May 6,

14 EMI Testing Successful EMI testing covered a large range of frequencies while carefully examining instrument data >5000 Excitation Frequencies / Conditions >1300 Spectral Channels and Other Telemetry Points Monitored Testing was very successful Nearly all conditions fully compliant Less than 20 minor discrete outages out of over 64 million test conditions and/or telemetry points tested All were carefully reviewed by spacecraft / user communities and found to be acceptable for flight e.g., minor outages identified for frequencies that are not used by NPP spacecraft May 6,

15 FOV Profiles/Shapes Are Well Within Spec Limits Well Defined FOV Shapes Measured; Very Stable Over Temperature May 6,

16 Superb Optical Stability Coregistration Requirement Maximum coregistration error is well below requirements Subsequent shifts over temperature during TVAC testing were small Maximum shift during vibe was below measurement uncertainty level Shifts were not statistically significant Coregistration PQH MN PQL Coregistration Spec Limit is <0.196 km at Nadir FOV1 FOV2 FOV3 FOV4 FOV5 FOV6 FOV7 FOV8 FOV9 May 6,

17 ILS And Spectral Accuracy Tests Thorough test program conducted to characterize ILS shape and spectral accuracy performance Tests utilized a combination of gas cell absorption lines and laser measurements CO 2, CH 4, and HBr gases used for absorption line measurements at all TVAC plateaus CO 2 laser measurements at ~10 um used for LWIR ILS shape measurements Performance has been outstanding under all conditions May 6,

18 LWIR Absorption Lines Overlay Very Well After Spectral Correction 1.2 Full Band PQH LWIR Side 1 Full Band 1.0 Transmittance When Absorption Lines Absent 1 Range of Interest LWIR CO2 SDR and LBL Transmission Line Centers Match Almost Perfectly transmittance Some Transmittance Peaks Slightly Above 1.0 Due to Sinc ILS Sidelobe Overshoots FOV1 FOV2 FOV3 FOV4 FOV5 FOV6 FOV7 FOV8 FOV9 LBLRTM wavenumber Transmittance Line Depth Matches Very Well FOV1 FOV2 FOV3 FOV4 FOV5 FOV6 FOV7 FOV8 FOV9 LBL Wavenumber (cm -1 ) May 6,

19 Spectral Accuracy Results Are Excellent All spectral accuracies are well within spec limit of <10 ppm FOV-to-FOV values in TVAC range from about one-fourth of spec to about two-thirds of spec Results are stable over a wide PQL-to-PQH temperature range Changes in spectral accuracy over temperature are relatively small May 6,

20 Noise Equivalent Spectral Radiance (NEdN) NEdN is an excellent indicator of overall instrument performance Numerous design elements must be functioning well in order to achieve specified NEdN levels High optical throughput with low wavefront errors High detector D* High interferometer modulation efficiency with low optical tilts Low noise levels from electronic signal processing NEdN is measured over TVAC temperature range, and over multiple scene temperatures (minimum to maximum expected) May 6,

21 Mission Nominal: Measured NEdN Performance Spec Limit = 0.118* at 855 cm -1 LWIR Spec FOV1 FOV2 FOV3 FOV4 FOV5 FOV6 FOV7 FOV8 FOV9 Spec Limit = * at 1510 cm -1 MWIR Spec FOV1 FOV2 FOV3 FOV4 FOV5 FOV6 FOV7 FOV8 FOV Wavenumber (cm -1 ) Wavenumber (cm -1 ) SWIR Spec Limit = * at 2355 cm -1 Spec FOV1 FOV2 FOV3 FOV4 FOV5 FOV6 FOV7 FOV8 FOV9 Measured MN NEdN Performance is Significantly Better Than Requirements in All Spectral Channels Some Minor Exceedances Observed at PQH Condition, But This Condition Never Occurs for FM1 On-Orbit Wavenumber (cm -1 ) *mw / (m 2 sr cm -1 ) May 6,

22 Long-Term Repeatability (LTR) Test Purpose of Test: Verify that the drift in the absolute radiometric calibration of the instrument is within spec limits over a 30-day period Test is performed by processing operational data sets, and measuring the standard deviations of the data sets LTR combines data sets which span ~45 days for Side 1 and ~43 days for Side 2 Each data set has >900 samples Data for all bands and both instrument sides is compliant with significant margin May 6,

23 FM1 Measured Long-Term Repeatability Spec: <0.3% Spec: <0.25% Spec: <0.22% Long-Term Repeatability Measured LTR Performance is Significantly Better Than Requirements in All Spectral Channels LTR Spec FOV1 FOV2 FOV3 FOV4 FOV5 FOV6 FOV7 FOV8 FOV Wavenumber (cm -1 ) May 6,

24 Absolute Radiometric Uncertainty Test Purpose of Test Compare output radiance of External Calibration Target (as measured by FM1) to the ECT s calculated output radiance (using the ECT s measured temperature) The ECT is a high-emissivity calibration target used for ground test purposes only Goal is for the two values to agree to within the combined uncertainties of FM1 and the ECT ECT spec error is added to the CrIS Radiometric Uncertainty specs In the following results, all corrections are applied, including non-linearity correction, and an improved ICT environmental model correction Results show that FM1 calibration accuracy is excellent May 6,

25 Radiometric Uncertainty Test Results: MN, 233K ECT LWIR and MWIR Non-Linearity Corrections Are Excellent (All FOVs Collapse Together) Errors Are Well Within Combined Spec Limits Radiometric Error Relative to ECT Overall Errors Are Very Small FM1 Spec FM1 Spec Limits are 0.45% (LWIR), 0.58% (MWIR), and 0.77% (SWIR) FM1 Spec + ECT Spec Wavenumber (cm -1 ) May 6,

26 Radiometric Uncertainty Test Results: MN, 287K ECT LWIR and MWIR Non-Linearity Corrections Are Excellent (All FOVs Collapse Together) Radiometric Error Relative to ECT ICT Environmental Correction is Very Effective (Minimal Spectral Structure) Residual Slope in Data Suggests a Small Residual ECT or ICT Temperature Error FM1 Spec FM1 Spec Limits are 0.45% (LWIR), 0.58% (MWIR), and 0.77% (SWIR) FM1 Spec + ECT Spec Wavenumber (cm -1 ) May 6,

27 CrIS EDU3 Used As Pathfinder For NPP CrIS EDU3 is very similar to flight unit, especially in regards to interfaces and software Integration tests at BATC with NPP spacecraft have been performed Very few issues found Extensive experience gained with operating the CrIS instrument May 6,

28 Summary Of CrIS FM1 Testing The CrIS FM1 instrument has successfully completed comprehensive performance testing, and is now in the process of being delivered for spacecraft integration CrIS instrument performance is outstanding and will meet the mission needs for the NPP and NPOESS missions The CrIS Sensor will provide the user community with significant new capabilities for atmospheric soundings CrIS FM1 Meets the NPOESS Mission Requirements with Margin May 6,