eMAS (enhanced MODIS Airborne Simulator)

Earth Science Technology ForumPasadena, CA 22 June 2101

Jeff MyersAirborne Sensor Facility

UCSC/Ames Research Center

Steve PlatnickEOS Project Science Office

Goddard Space Flight Center

Outline

• eMAS Rationale • System Description & Design Criteria• LW/MWIR Spectrometer for eMAS Line-Scanner• V/SWIR Pushbroom Imaging Spectrometer• Implementation Schedule

The eMAS project rationalePurpose:

To provide the next generation of an airborne MODIS-like instrument with:

1. High spatial resolution

2. Broad range multi-spectral coverage (VNIR/SWIR-MWIR-LWIR)

3. Co-registered bands

4. A wide FOV for large area coverage

5. Repeatable spectral and radiometric calibration

6. Robustness for sustained operations

7. Mechanical cooling for long missions (e.g., Global Hawk)

… to support current and future satellite programs (e.g. HyspIRI and JPSS) as well as multi-disciplinary process studies.

The MODIS and ASTER Airborne Simulators (MAS & MASTER) are the only sensors of this type in the world, but have been heavily utilized and are nearing the end of their service life.

70

40

60

50

30

20

10

’95 ‘96 ’97 ‘98 ’99 ’00 ‘01 ’02 ‘03 ’04 ‘05 ’06 ‘07 ‘98 ’99 ’00 ‘01 ’02 ‘03 ’04 ‘05 ’06 ’07 ’08 ’09 ‘10

Reimbursable

Collaborative

Other NASA

RA

EOS

Historical MAS & MASTER Utilization(Not including test and calibration flights)

MASTER469 Flts

MAS535 Flts

Level-2 “Quick-Look” Image Products(MASTER TC-4)

Typical Level-2 geophysical products

(As Produced by the MODIS/MAS Cloud Team)

eMAS Project Overview

eMAS-HSI Imaging Spectrometer

New Stirling-Cooled MW/LWIR Spectrometer

Re-Built MAS Fore-Optics

ARRA Elements:1. Upgrades to the existing MAS line-scanner (“eMAS-Scanner”)2. New stand-alone VNIR/SWIR Imaging Spectrometer (“eMAS-IS”)

EOS/R&A Elements:1. New digitizer & data system2. New scanning fore-optics

eMAS will be a suite of two bore-sighted, synchronized, instruments:eMAS Scanner

(Dual-Offner V/SWIR Pushbroom)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

tran

smitt

ance

wavelength (nanometers)

Atmospheric Transmittance

transmittance

eMAS

eMAS HSI

HYSPIRI

VIIRS

VNIR-MWIR Spectral Band Positions:eMAS-Scanner and eMAS–Imaging Spectrometer

HypsIRI

VIIRS

Existing MAS Port 1 & 2

Single eMAS MWIR Band

De-scoped eMAS-Scanner MWIR Bands

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000 13500 14000

tran

smitt

ance

wavelength (nanometers)

Atmospheric Transmittancetransmittance

eMAS

HYSPIRI

VIIRS

LWIR Spectral Band Positions:eMAS-Scanner

HypsIRI

VIIRS

eMAS-IR Spectrometer (Space Dynamics Laboratory)

• Cryogenic Optical Bench – reduced background noise– Increased stability from environmental isolation – eMAS scanner in unpressurized compartment of superpod

• Distortion-Correcting FPA design – Reduced spectral crosstalk– Increased signal to detectors

Cryo-Cooled Spectrometer

Section

eMAS-Scanner MW/LWIR Band Comparison

EMAS Similar Bands in other instruments

Channel CWL µm FWHM µm VIIRS MODIS MAS

MW1 3.65 0.18 M12 20 30

LW1 6.72 0.25 -- 27 --

LW2 7.33 0.26 -- 28 --

LW3 8.28 0.26 -- -- --

LW4 8.55 0.26 M14 29 42

LW5 9.73 0.26 -- 30 43

LW6 10.2 0.26 -- -- 44

LW7 11.03 0.26 M15 31 45

LW8 12.02 0.26 M16 32 46

LW9 12.6 0.26 -- -- --

LW10 13.34 0.26 -- 33 48

LW11 13.64 0.26 -- 34 --

LW12 13.94 0.26 -- 35 49

MAS SWIR Spectrometer MAS VNIR Spectrometer

New eMAS-IR Spectrometer installed on optical bench

Cryogenic Optics Enclosure

Cryocooler

Vacuum Housing

Preamp Electronics Box

Vacuum Gage

Getter

Vacuum Port/Valve

P2 Beamsplitter50pin Connector

(x3)

Rad Shield and Cryogenic Optics Bench

LN2 Heat Exchanger

Radiation Shield (gold plated on outside, black on inside)

Optical BenchThermal Links

G10 Mounts

Internal Optics Bench Subassembly

15

Gut Ray

Dichroic Beamsplitter(MWIR reflected, LWIR transmitted)

LWIR Lens

Cold Entrance Aperture

Fold Mirror

MWIR Lens

Fold Mirrors

Thermal Isolator Mount

LWIR FPA

Fold Mirror(MWIR Grating Replacement)

LWIR Grating

LWIR Images of Field Stop at LWIR Detector Focal Plane

Apert ure Ful l X Wi dt h : 16. 4000Apert ure Ful l Y Hei ght : 0. 5580

Scale: 0.5800 Millimeters

6. 7150 7. 3250 8. 2800 8. 5500 9. 7300 10. 2000 11. 0300 12. 0200 12. 6000 13. 3350 13. 6350 13. 9350

EMAS_Port 4_V5f _Col d. ZMXConf i gurat i on 1 of 1

Foot pr i nt Di agramMAS Model11/ 13/ 2010Surf ace 50: DETECTORRay X Mi n = -8. 3810 Ray X Max = 8. 3492Ray Y Mi n = -0. 2875 Ray Y Max = 0. 6379Max Radi us= 8. 3811 Wavel engt h= Al l

% rays t hrough = 63. 65%

BandCENTER

WAVELENGTHlabel (µm)

L1 6.715L2 7.325L3 8.280L4 8.550L5 9.730L6 10.200L7 11.030L8 12.020L9 12.600

L10 13.335L11 13.635L12 13.935

Distortion corrected FPA

Distortion corrected FPA

Field Stop images land precisely on FPA detectors

eMAS-HS Spectrometer (Brandywine Photonics)

• Dichroic split dual Offner system, sharing one slit and fore optic• Fore-optic is a 4 mirror anastigmat, 50 degree FOV, low distortion • SWIR Spectrometer uses a cryogenic MCT FPA from Sofradir

– Variable gain capability on a row by row basis (rows = spectral bins)• System enclosed in 0.8 atm. pressurized box

– Contained in the pressurized ER-2 superpod section– Increased confidence in ground based calibrations during flight

• Radiometric Stability Monitor– Flip mirror to feed broadband light source to illuminate the slit – Periodic check of system stability during flight

SWIR Spectrometer

VNIR Spectrometer

Telescope

EMAS-HS Radiance requirements

L-max

L-typ

Desired NEdL

Required NEdL

EMASHSI SNR RequirementsL-max

First Order Propertyf/# f/2.8Slit size 32 µm X 26.56 mmField of View +/-25° FFOV, 2.1mRad IFOVGround projection distortion <8 µm cross-track, <12 um along trackSpatial resolution 832 spatial samples cross trackVNIR Spectral Bands 256 X 2.5 nm resolution (2 x 1 binning)SWIR Spectral Bands 140 x 10 nm resolution VNIR Slit Magnification 1:1SWIR Slit Magnification 32:30

EMAS-HS First Order Properties

Focal Plan Arrays

Sarnoff CCD160-250-SFT VNIR Detector Array• 16 μm pitch, 2048 x 256 pixels• Binning 2x1 on-chip, storing 830 x 256 pixels per frame• Corresponds to 1.05 mRad IFOV• Spatial binning to 2.1 mRad in post-processing• Spectral sampling at 2.5 nm/band, post-processing to 10 nm

Sofradir Saturn HgCdTe SWIR Detector Array• 30 μm pitch, 1000 x 256 pixels• Storing 830 x 150 pixels• Spectral sampling 10nm/band• Programmable gain settings, by row

Ground Sample Distortion

• Requirement to have a flat cross track ground sample

– across a 50 degree wide field of view – in order to closely match eMAS

scanner system

• Requirement flows down to demanding telescope design

– Four un-obscured aspheric mirror design

0.34 pixel

25 Deg.

Along-Track Distortion

0 Deg.

Schedule

• IR Spectrometer Delivery: 10/1/2011• Integration into ER-2 Super-Pod: 1Q CY2012

• V/SWIR Imaging Spectrometer Delivery: 1/30/2012• Integration into ER-2 Super-Pod: 2Q CY2012 (TBD)

Requires major mid-body hatch modification

• Engineering Test Flights ~ July 2012eMAS IR Line-scanner may fly first