# Presentation: 004591

## Section 7

_***Section 7***_
***Atmospheric Corrector***

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

## LEISA Atmospheric Corrector (LAC) Contribution to EO-1

***LEISA Atmospheric Corrector (LAC) 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-comparison with MODIS***

## LAC BLOCK DIAGRAM

***LAC BLOCK DIAGRAM***

- 3 Wedged Filter/ Array Assemblies

- 

-  Lenses

**OPTICS MODULE**

- digital

- power

- bias

- clock

- TEC

**ELECTRONICS**

**     ****MODULE**

- Power Conversion

- 28 V

- RS 422

- Digital Buffers and

-   Formatting

- 1773 Interface, Array

- Control and TEC Control

- 1773

**SPACECRAFT**

## LAC Characteristics

***LAC Characteristics***

***High Spectral - Moderate Spatial Resolution Hyperspectral Imager using Wedged Filter Technology (LVE).***
***Spectral Coverage:  ~0.9 - 1.6 mm; 256 Bands Selected for optimal correction of High Spatial Resolution Images. ***
***Spectral Resolution:  35 cm-1 (Dl: 3 nm @ 0.9 mm, 9 nm @ 1.6 mm)***
***Swath Width:  ~185 km; Matches Landsat.***
***Spatial Resolution (pixel):  356 mradian (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).***

## Performance Testing

***Performance Testing***

***Box Level***
***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   ***

## 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, XBPAA, etc.)

***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, XBPAA, etc.)***

***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 

***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 ***

***LAC Test Descriptions***

## LAC Test Results / Actions

***LAC Test Results / Actions***

***Vibration (Proto-flight, Module Level): ***
***OM: Arrays contacted by LVE; some damage to arrays and LVEs; wire bonds broken on one array***
- Incorrect assembly of LVE mount
- Wire bonds repaired on array
- One LVE replaced with flight spare
- LVE mount re-assembled correctly
- Module re-vibrated with no damage
***EM: 1773 Fiber Alignment Cylinder Cracked***
- Failure mode observed in other 1773 interface applications
- Cylinder replaced
- Module re-tested with no damage
***Vibration (Satellite, Instrument Level): No damage ***

## LAC Test Results /Actions

***LAC Test Results /Actions***

***EMI/EMC:***
***Excessive radiated / conducted Emissions (20 - 30 dB in some places)***
- Interpoint Power Supply filtering
- Additional Filter Assembly mounted on EM
- Filter reduces excess emissions to at most 5 dB - waiver granted
***Components destroyed during conducted Susceptibility Test***
- Incorrect test conditions
- Components replaced
- Test was not repeated - waiver granted

## Thermal Vacuum (before Spacecraft integration):
Instrument operated for approximately 10 hours
Mount temperatures < 25° C, continuous operation for 1 hour  
Mount temperature 30° C, Digital Board overheated in ~ 40 minutes
No modification: Maximum operating time in-flight 20 minutes  
Thermal Vacuum (Spacecraft):
Instrument operated for approximately 20 hours
Dark current consistent with previous results
Mount 40° C: Power Board reached Red-Limit temp in < 5 minutes
Power board Red-Limit set for mount temperature at < 30° C: Models indicate Red-Limit can be increased ~ 20° C
Excellent TEC control 

***Thermal Vacuum (before Spacecraft integration):***
***Instrument operated for approximately 10 hours***
- Mount temperatures < 25*° *C, continuous operation for 1 hour* *
- Mount temperature 30*°* C, Digital Board overheated in ~ 40 minutes
- No modification: Maximum operating time in-flight 20 minutes
***Thermal Vacuum (Spacecraft):***
***Instrument operated for approximately 20 hours***
- Dark current consistent with previous results
- Mount 40*° *C: Power Board reached Red-Limit temp in < 5 minutes
- Power board Red-Limit set for mount temperature at < 30*° *C: Models indicate Red-Limit can be increased ~ 20*° *C
- Excellent TEC control

***LAC Test Results /Actions***

## LAC Test Results /Actions

***LAC Test Results /Actions***

***Optical Calibration***
***Radiometric ***
- Initial results consistent with models
- Offset error limits dynamic range to 11 bits. Difficult to differentiate High Albedo from Specular Reflection
- Unexpected temperature dependence of Quantum Efficiency
***Spectral***
- Filters have excellent spectral characteristics
***Alignment: Within 2 arc-min of ALI Track -- achieved 1***
***Flat Field: Solar Calibrators consistent with Diffuse Illumination***

## Modifications

***Modifications***

***Software***
***Red-Limits on currents eliminated ***
***TEC set-points lowered to reflect improved thermal results on Spacecraft***
***Hardware***
***No additional hardware modifications required ***
***NO SIGNIFICANT OPEN ISSUES: INSTRUMENT HAS RUN SEVERAL HUNDRED HOURS *****~ 50 *****TROUBLE-FREE ***
***REQUIRED ORBITAL OPERATION ~ 50 HOURS***

## Waivers and NCRs

***Waivers and NCRs***

***5 waivers***
***3 EMI / EMC***
***Parts tracability***
***Degraded performance of TEC #3 during instrument T/V***
*Not apparent in Spacecraft T/V tests*
***9 NCRs***
***Waivers and NCRs available in GSFC system***