The LEISA Atmospheric Corrector (LAC) on Earth Observer 1 (EO1)

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The LEISA Atmospheric Corrector (LAC) on Earth Observer 1 (EO1)

  1. 1. LEISA Atmospheric Corrector (AC) on EO1 George McCabe NASA/Goddard Space Flight Center Code 693 Greenbelt, MD 20771
  2. 2. LEISA Development History • 1993 Selected for Pluto Express (PE) Mission under Advanced Technology Insertion Program • 1993 Baseline IR spectral imager for Highly Integrated Pluto Payload System (HIPPS) • 1994 Chosen for Small Satellite Technology Initiative (SSTI) Lewis Mission • 1996 Chosen for New Millennium Program Earth Observing-1 (EO-1) Mission • 1997 Space Act Agreement, participation in Field Studies with Boeing Commercial Space Company, Resource21 • 2001 Phase B development New Horizons for NASA Pluto-Kuiper Belt Mission
  3. 3. Instrument Characteristics • Correct Atmospheric Effects in High Spatial Resolution Multispectral Imager Data – Hyperspectral Imager – Moderate Spectral Resolution (<10 nm) – Moderate Spatial Resolution (<300 meter) – Maximum Sampling Flexibility – Minimum Impact on Spacecraft Resources
  4. 4. Wedged Filter Operation
  5. 5. LEISA Data Cube
  6. 6. Sample Image (Arid Lands Ecological Reserve)
  7. 7. Contribution to EO-1 • Validation of Wedged Filter Approach for Spacecraft Instrumentation • Atmospheric Correction for ALI Multispectral Images. • Atmospheric Correction for Landsat-7 Images (Formation Flying). • Direct Study of Spatial Resolution Degradation (CrossComparison with Hyperion). • Retrieved Atmospheric Parameters. • Cross-Comparisons with MODIS.
  8. 8. EO-1 Landsat-7 Less Than 1 Minute Hyperspectral Atmospheric Correction (185 km @ 125 / 250 m) Multispectral Images (36 km @ 30 m) TRWIS Underflight (Variable) 705 km Altitude AVIRIS Underflight (10 km @ 20 m) 36 km Landsat Multispectral Images (185 km @ 30 m) Grating-based Hyperspectral Images (7.5 km @ 30 m) 7.7 km 185 km
  9. 9. AC Instrument Specifications • • • • • • • • • Spectral Coverage: 0.89 - 1.58 _m; 256 Bands Selected for Optimal Correction of High Spatial Resolution Images Spectral Resolution 2 Filter Sections: Section 1 ~35 cm-1 (__: 5 nm @ 1.2 _m, 9 nm @ 1.6 _m) Section 2 ~55 cm-1 (__ : 4 nm @ 0.9 _m, 8 nm @ 1.2 _m) Swath Width: ~185 km; Matches Landsat Spatial Resolution (pixel): 356 _radian (250 meter @ 705 km) Three 256 x 256 Element InGaAs Arrays; TEC Stabilized (<285 K) Three 15 Degree FOV 3 Element Lenses Two Modules: “Bolt-on”Optics Module and Electronics Module Mass: 10.5 kg (EM, 4.4 kg; OM 3.9 kg; Cable 2.2 kg) Power: 48 W (Peak); <15 W (Orbit Average)
  10. 10. AC Linewidths
  11. 11. Optics Module Detail
  12. 12. In-Flight Calibration • • • • Solar Calibration – Radiometric Calibration (Relative and Absolute) – Radiometric Stability – Variable Light Level Response – “Fixed Pattern” Noise Correction Lunar Calibration – Radiometric Calibration – Image Quality – Extended Duration Dark Current Stability Surface Targets – Radiometric/ Spectral Calibration (Ground Campaigns) Dark Earth Looks – Dark Current Stability
  13. 13. ‘Fixed Pattern’ Signal
  14. 14. Extended Calibration “Fixed Pattern” Signal Apparent After Launch – Predominantly Additive Contribution – Constant in Position and Time – Reduced Accuracy in Low Illumination Modified Radiometric Correction Procedure – Requires Measurements Unaffected by Atmospheric Absorption, Use Scanning Solar Data – Scale Calculation Replaced by Calibration Lookup Table
  15. 15. Atmospheric Corrector Calibration System ACCS EO1 Level-0 Data EXTRACT REDUCE VERIFY Temporary Storage ARCHIVE DELIVER Permanent Database Level-1 Products
  16. 16. ./rsi/idl_5.3 ./ncsa/HDF4.1r3 ./ncsa/4.1r3_irix64-64 ./idldev/L0 ./idldev/ACCS ./idldev/ACCS/bin ./idldev/ACCS/dev ./idldev/ACCS/doc ./idldev/ACCS/lib ./idldev/ACCS/data ./idldev/ACCS/install ./idldev/varosi ./idldev/astron ./idldev/freudenreich ./idldev/sterner_98apr ./gdaac/hdfeos Calibration System Software •150+ program modules
  17. 17. Processing Options accs@fastie-bin-2 LAC_Option -l to_level 1R keepall_prod yes eo1q_execute standard null_calibration no offset_source local_dark scale_source default replace_bad yes force_cal no cal_matchkey preset2 enhance_qlook yes deliver_to lacsend archive_file lacstor post_cleanup yes do_tapels both mail_report yes getsome_sleep yes lookforward2_vacation yes # # # # # # # # # # # # # # # # # 1R, 1G no (highest only), yes none, standard, extended no, yes default, local_dark default, extended, local_cal no, yes no, yes preset2, facist3, preset1, anarchist0 yes, no lacsend, tarsend, tape, null lacstor, tape, null no, yes both, tape, eo1tape, none no, yes yes, no yes, no
  18. 18. Session Logs • goACCS_EO1###.log • LAC_Extract/Reduce0/Deliver/ArchiveYYYYMonDD@HHMMSS.log • goClean.log • dat3/dlt4_ACCS###.lst • Scenes_Processed.lst
  19. 19. ACCS Performance • • • > 1500 scenes processed 8.5 Gb of data per session 1.5 hrs/Gb total processing time* ( Extract + Reduce + Archive ) * excepting extended calibration
  20. 20. HDF File Creation Example L0 = LACDATA+‘/lac/20013010839_AKS/EO11520372001301112K0/’+ $ ‘AC2001301054952_AKS_01.L0’ GENICAL, L0, /VERBOSE, /OFFSET, $ MATCH={TYPE:1,TIME:1.0,ARRAY1T:10,ARRAY2T:10,ARRAY3T:10,STAT:'0111'} GENHDF, L0, RUN_LABEL='2002Jan23@064222', /VERBOSE, /NON_INTERACTIVE L1 = VERYGEN1R( L0 ) TIMEUPDT, L1 GEN1RSDS, L1 RDUPDT, L1, /NON_INTERACTIVE
  21. 21. Associated Files • YYYY_DDD_lac/gps/acs.hdf • 00indexEO1### • ACYYYYDDDHHMMSS_RRR_##.L0_calcoef.b4 • " .L0_calpnotes.txt • • • • • • " " " " " " .L0_stats .L0_stats-M/S.bmp .L0_trace0/C .L0/1R_wint .L0_update .L1R_q-bands/frames.jpg • " .L1R_geo
  22. 22. Level-1 HDF Products Level-1R Level-1G Type HDF v4 Grid HDF-EOS v2.4 Swath Processing Inputs L0 Science, L0 Dark, scale coefficients, lac / gps / acs metadata L1R Science, lac / gps / acs metadata, pointing map, wavelength map, corrected frame times Key Attributes Data Start Time, Level 1R: Dataset Type, Response SD: Filenames, Scale Factor Spectra: Scale Factor SD Structures Offset, Response, Pixel_Map, Wavelength_Map, Level 1R (radiometrically calibrated, 768 x Nframes x 256) Latitude, Longitude, Wavelength, Spectra (geo-located and band rectified, NY x NX x 256) Associated Products Raw frame/pixel statistics, quicklook images, ENVI header Geo-location info Usage Modified ENVI input procedures (BSQ) ENVI Generic HDF (BIP)
  23. 23. Science Data Formats • instrument clock, header data • pixel pointing map, filter frequency map • spacecraft meta data (YYYY_DDD_lac/gps/acs.hdf) Ii,j,t ⇒ Ix,y,ν ν Level-1R Level-1G
  24. 24. Band Alignment Scan of Cuprite, NV 1200 frames
  25. 25. Color Composite Image Cuprite, NV Mar. 1, 2001 red=1.32, green=1.03, blue=0.98 (µm)
  26. 26. Spectra Cuprite, NV March 1, 2001 3000 2500 2000 1500 1000 500 0 0.9 1 1.1 1.2 1.3 1.4 1.5 -500 [298,600] [299,599] [299,600] [299,601] [546,584] [546,585] [546,586] [547,585] 1.6
  27. 27. Cuprite, NV Scene-ID: EO10410342001060111PP Lake Frome Scene-ID: EO10970812001021111PP Rochester, NY Scene-ID: EO10160302001125111PP Snake River Scene-ID: EO10410302001140111PP Suez Canal Scene-ID: EO11760392001046111PP Venice Scene-ID: EO11920282001158112PP

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