# Presentation: 307259

## Section 7

***LEISA Atmospheric Corrector (LAC)***

*** ******. . . Dennis Reuter***
*EO-1 LEISA Atmospheric Corrector*

## Requirements

***Requirements***

***Correct High Spatial Resolution Multispectral Imager Data for Atmospheric Effects***
***Hyperspectral Imager***
***Moderate Spectral Resolution (<10 nm)***
***Moderate Spatial Resolution (<300 meter)      ***
***Minimize Impact on Spacecraft Resources***
***Maximize Flexibility***

## Contribution to EO-1

***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 (Cross-Comparison with Hyperion).***
***Retrieved Atmospheric Parameters.***
***Cross-Comparisons with MODIS.***

## LAC Block Diagram

## Wedged Filter Operation

***Wedged Filter Operation***

## Wedged Filter Schematic

## Filter Layer Composite Detail

## Optics Module Detail

## LAC Internal Detail

## LAC Performance

***LAC Performance***

***Spectral Coverage:  ~0.9 - 1.6************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 (Orbital Average)***

## LAC Line Widths

***LAC Line Widths***

## LAC Half-Width Summary

***LAC Half-Width Summary***

## LAC System Trades

***LAC System Trades***

***Spatial Resolution vs. Spatial Coverage***
***250 meter spatial resolution near maximum required for atmospheric correction  ***
***185 km Matches Landsat7 ***
***Requires three 256 x 256 arrays ***
***Thermo-Electric Coolers (TEC) vs. Passive Radiators***
***TECs require more power, but significantly simplify integration and operations***
***Wedged Filter vs. Conventional Technologies***
***Wedged filter data Analysis systems not as developed but instrument has less mass and complexity than conventional ***
***No moving parts***

## LAC System Trades

***LAC System Trades***

***IR vs. Visible Spectral Coverage***
***IR gives better water vapor and cirrus cloud information at the expense of aerosol information   ***
***InGaAs arrays now can cover 0.5 to 1.7 micron  ***
***1.6 vs. 2.5 micron Longwave Cutoff***
***Cryogenic cooling not required***
***Two Module vs. 1 Module Design***
***Gain in system flexibility and platform independence compensates for increased mass and additional integration  ***

## LAC Performance Testing

***LAC Performance Testing***

***Box Level***
***All Cards Simulated on an Individual Basis ***
***TECs Tested with Engineering Backplane (Focal Plane)***
***Focal Plane Timing Tested with Multiplexers   ***
***Subsystem Level***
***OM: Limited Set of Images Obtained with EM Simulator***
*  **Engineering Model Vibration Tested *
***EM: Operation Tested by Interface to OM Simulator***
***Instrument Level***
***Vibration and Thermal-Vacuum***
***Radiometric/ Spectral Calibration and Alignment***
***EMI/EMC   ***

## LAC Test Descriptions

***LAC Test Descriptions***

***Vibration: ***
***Individual Modules Tested to Proto-flight Level (1.25 X Expected Maximum Flight Loads)***
***Instrument Mounted on Spacecraft and Tested to Flight Level***
***Thermal Vacuum (Pre-spacecraft Integration): ***
***Four Cycles to Survival Levels (-10° C to + 50° C; Range Expected on Orbit 20° C ± 10° C )***
***Operation from 0° C to 30° C (Orbital Predict 20° C, 30° C Worst Case) ***
***Images Obtained Using LAC GSE***
***Thermal Vacuum (Integrated with Spacecraft): ***
***Four Cycles***
***Operation from 0° C to 30° C (No Operation at 40° C) ***
***Images Using Spacecraft System (WARP, XPAA, etc.)***

## LAC Test Descriptions

***LAC Test Descriptions***

***EMI/EMC: ***
***Instrument Level Tests: Conducted and Radiated Emissions, and Radiated Susceptibility ***
***Alignment:***
***Orientation of Arrays with respect to Alignment Cube Using Theodolites ***
***LAC Alignment to ALI on Spacecraft Using Theodolites ***
***Optical Calibration: ***
***Wavelength and Instrumental Shape: Grating Monochrometer 1 to 100 nm Steps***
***Radiometric: Calibrated Black-body (all 4 TEC Settings) ***
***Flat Field: Diffuse Source Illuminating Lenses and Solar Calibrators ***

## Data Flow

***Data Flow***

## LAC on Spacecraft

***Atmospheric Corrector on EO-1 ***
***Three lenses are nadir facing  ***
***Solar Calibrators are facing forward  ***
***Alignment cube on right***

## LAC Pre-Launch

## LAC Comparative Size

## LAC Technology Transfer

***LAC Technology Transfer***

***Compact design adaptable to many moderate Spatial Resolution Hyperspectral applications ***
***Optics Module adaptable to redesign for differing spatial resolutions***
***Electronics Module adaptable to redesign for differing spacecraft interfaces ***
***Spectral coverage/spectral resolution selectable by choice of Wedged Filter***
***0.5 to 1.7 ************m InGaAs Arrays Available***
***GSFC owns this design and is willing to infuse it into any U.S. commercial or academic institution***

## LAC Image of Niger3 (1.243 m)

## Landsat Image of Niger3

## LAC Image of Niger3 (1.383 m)

## LAC Image of Panorama (1.243 m)

## Landsat Image of Panorama