The LEISA Atmospheric Corrector (LAC) on Earth Observer 1 (EO1)
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The LEISA Atmospheric Corrector (AC) on EO1 was selected in 1993 for a planned Pluto mission and later chosen for the Earth Observing-1 (EO-1) mission in 1996. It is a hyperspectral imager that collects moderate spatial and spectral resolution data to correct atmospheric effects in high spatial resolution multispectral images. It has contributed to EO-1 through atmospheric correction of ALI and Landsat-7 images and studies of spatial resolution degradation by comparing to Hyperion.
![Spectra
Cuprite, NV
March 1, 2001
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1.6](https://image.slidesharecdn.com/15c-laconeo1-140221104333-phpapp01/85/The-LEISA-Atmospheric-Corrector-LAC-on-Earth-Observer-1-EO1-26-320.jpg)
The LEISA Atmospheric Corrector (LAC) on Earth Observer 1 (EO1)
- 1. LEISA Atmospheric Corrector (AC) on EO1 George McCabe NASA/Goddard Space Flight Center Code 693 Greenbelt, MD 20771
- 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. 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
- 6. Sample Image (Arid Lands Ecological Reserve)
- 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. 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. 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. AC Linewidths
- 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
- 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. Atmospheric Corrector Calibration System ACCS EO1 Level-0 Data EXTRACT REDUCE VERIFY Temporary Storage ARCHIVE DELIVER Permanent Database Level-1 Products
- 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. Session Logs • goACCS_EO1###.log • LAC_Extract/Reduce0/Deliver/ArchiveYYYYMonDD@HHMMSS.log • goClean.log • dat3/dlt4_ACCS###.lst • Scenes_Processed.lst
- 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. 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. 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. 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. 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. Band Alignment Scan of Cuprite, NV 1200 frames
- 25. Color Composite Image Cuprite, NV Mar. 1, 2001 red=1.32, green=1.03, blue=0.98 (µm)
- 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. 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