DLR Earth Sensing Imaging Spectrometer (DESIS)

Status and Calibration Update

• Coverage of ~90% of populated Earth

• Coverage of ~100% of ocean shipping lanes and major navigational ports

• Coverage of 100% of tropics and equatorial region

• Sophisticated spacecraft bus with required resources

• Upgrade and exchange of instruments as technology and/or markets evolve

• Traditional barriers to entry minimized

Earth Observation From the ISS – Why It Works

Remote Sensing Platform

Designed, built, owned & operated

by Teledyne

Facility Class Payload on ISS

• Up to 4 attached instruments

• Installed and removed robotically

Launched on June 3, 2017

• Full Operational Capability

Multi-User System for Earth Sensing (MUSES)

MUSES Platform Capabilities

Characteristic MUSES Performance Target

Field of Regard

Outboard Cross-Track: 5°

Inboard Cross-Track: 45°

Along-Track: +/- 25°

Thermal Control Passive

Star Tracker Sodern SED26

Inertial Measurement

Unit

Honeywell Miniature Inertial Measurement Unit

(MIMU)

Precision TimeSourced from the ISS GPS,

≤ ± 250 μsec to MUSES instruments

Pointing Accuracy ≤ ± 60 arc seconds

Pointing Knowledge≤ ± 30 arc seconds

(~ 60 m on ground from 400 km altitude)

Location knowledge Sourced from the ISS GPS, ± 50 meters, RMS

Orbit 51.6° Inclination, 400 km altitude ± 5% (nominal)

Data ProcessingLinux Server on-board ISS with redundant 6 TB

storage

Daily Downlink Capacity 225 GB

Miniature Inertial

Measurement Unit

External Wireless

Adapter

Power Control Unit

Star Tracker

MUSES Client

Computer

Inner Gimbal /

Pointing Platform

Electronic Control

Unit

Outer Gimbal

Ethernet Wireless

Controller

MUSES is located on ExPRESS Logistics Carrier 4(ELC 4) aboard the International Space Station

MUSES Location on the ISS

Payload Options

Secondary Payload Accommodations (2)

Maximum Mass: 50 kg

Maximum Height: 35”(92 cm)

Maximum Width: ~10” (~25 cm) dia Core

Maximum Power: 112W @ 28 Vdc

Primary Payload Accommodations (2)

Maximum Mass: 100 kg

Maximum Height: 35“(92 cm)

Maximum Width: ~18” (~46 cm) dia Core

Maximum Power: 224W @ 28 Vdc

Ride-Share Accommodations

Size / Mass: 6U-27U

Multiple payloads in a single canister enable a cost-

effective alternative to Cube-Sat free flyers.

Imaging and space qualification options with payload

return.

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DESIS-30: MUSES First Payload

• Teledyne and DLR partnered to build and operate the DESIS-30 instrument from the MUSES Platform on the ISS.

• Teledyne has commercial rights to imagery while DLR retains rights for scientific use.

• Launched on June 29, 2018.

• Installed on August 27, 2018.

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Instrument Specification

Characteristic DESIS Features

F# / Focal Length 2.8 / 320 mm, telecentric

FOV / IFOV 4.1° / 0.004°

Ground Sampling Distance 30 m @ 400 km altitude

Ground Swath 30 km @ 400 km altitude

Spectral Range 400 nm – 1000 nm

Spectral SamplingMeasured: 235 @ 2.55 nm

Programmable binning factor (1 to 4)

Quantization 13 bits + 1 gain bit

Spatial Pixels 1024

Radiometric Linearity 95% (10% - 90% FWC)

MTF @ Nyquist (no smearing) > 20%

FWHM < 3 nm

On-board CalibrationDark Field for DSNU

LED Array for PRNU

Independent Pointing Pointing Unit, ±15° Along Track

Independent Time and Position On-board GPS Figures courtesy of DLR.

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First Images

Image courtesy of DLR.

• Processed successfully to level 1C (georeferenced and resampled to UTM grid

using bilinear interpolation).

• Accuracy (linear in each principal direction –

north east was below one pixel size w.r.t.

Landsat ETM+ panchromatic worldwide

reference).

• The image is composed by the bands at 463

nm, 553 nm und 639 nm wavelength

mapped to BGR.

• Full Width Half Maximum (FWHM) of ~ 3.5 nm

for all bands.

DLR responsibility▪ Prelaunch calibration

▪ Initial instrument on-orbit checkout

▪ Calibration throughout system life

Onboard calibration

Vicarious calibration

TBE responsibility▪ Image quality validation

Automated tools and methods

▪ Support DLR calibration

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SpaceX CRS-15 Launch June 29, 2018

DESIS/MUSES Integration August 27, 2018

First Image w/in 48 hrs.

On-Orbit Checkout Aug-Sept 2018 Timeframe

On-Orbit Cal/Val Initiated Sept 2018

Early Data Available TBD as early as Oct 2018

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Summary of Activities:

▪ Integration of detector and optics (Alignment)

▪ Measurement of spatial and spectral mapping (interior geometry) MTF

FWHM

▪ Measurement of Smile/Keystone

▪ Absolute radiometric calibration

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Test equipment: gimbal with collimator, monochromator and integration sphere

The DESIS optical on-ground Calibration and Verification was performed in DLR’s calibration lab for two DESIS configuration levels:

▪ Sub-system: optics + sensor assembly + EGSE stand-alone on gimbal

▪ Full system: full instrument at container level (with CAL and POI unit)

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DESIS optics + sensor assembly level mounted on gimbal facing the collimator illuminated by monochromatic light from monochromator

DESIS optics + sensor assembly level mounted on gimbal and facing the absolute calibrated integrating sphere

Focusing and focus fixation Optics Wavefront Spectral mapping of center wavelengths and FWHM per pixel Spectral calibration using pen-ray lamps Flat-fielding and absolute calibration in spectral radiance Dark signal, linearity and saturation, hot pixels Photon Transfer Curve PTC Geometric calibration System /detector spatial MTF in spatial and in spectral direction Spectral calibration of the LED‘s of CAL unit Spectral calibration of CAL unit – in-flight spectral calibration procedure Radiometric calibration of CAL unit – in-flight radiometric calibration procedure POI unit performance, POI axis vs. Slit Polarization Focus, CAL unit vs. temperature @ TV test

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Covering full spectral range of DESIS (400 nm –1000 nm) with 9 different types of LEDs

IMOS lenses are used for collimating the light to a cone of ± 16°

Temperature stabilized

Calibration Unit used for PRNU cross-calibration and DSNU calibration

Total Dose Test (30 MeV) shows high stability of peak and dominant wavelength and spectralbandwidth

Most LEDs showed a 1% increase in intensity, but two LED types showed a decrease by 4%; this effect can be used to compensate LED degradation during in-flight

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Changes sight ±15° in the along-track direction

Earth Sensing Mode

▪ 11 measurement positions ±15° (every 3°)

▪ Repeatability / accuracy 0.004° (14 arc seconds)

▪ Target replacement time ≤ 0.5 seconds

BRDF Mode

▪ Collection of up 5 image tiles at different angles(30 km x 30 km tiles at nadir)

▪ Used for BRDF & altitude extraction

Forward Motion Compensation Mode (experimental)

▪ Used to increase SNR for specific targets

▪ Programmable speed between0.6 °/sec and 1.5 °/sec

▪ Accuracy better than 0.001° (1/4 pixel)

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A list of potential land acquisition targets for the DESIS sensor in support of:▪ Calibration (radiometric, spatial, geometric)

▪ Atmospheric Correction

▪ Validation

▪ Underflights and Coincident Satellites

Over 100 land target sites have been identified for inclusion

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Potential land targets selected for the collection deck are typically used by various groups, and may be instrumented▪ CEOS LandNet Sites

▪ CEOS Pseudoinvariant Calibration Site

▪ RadCalNet

▪ AERONET Sites

▪ NEON-Core Terrestrial Sites

▪ Ameriflux (DOE) and other flux networks

▪ LTER (Long Term Ecological Research)

▪ ARM (Atmospheric Radiation Measurement)

▪ NEON AOP (Airborne Observation Platform)

▪ DLR Calibration Sites

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A list of potential water acquisition targets for the DESIS sensor in support of:▪ Radiometric Calibration

▪ Validation

▪ Coincident Satellites

40 water target sites have been identified for inclusion

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Potential water targets selected for the collection deck are typically used by various groups, and may be instrumented

▪ MOBY (Marine Optical Buoy)

▪ BOUSSOLE (Buoy for the acquisition of long-term optical series)

▪ Pseudoinvariant Water Sites

▪ AERONET Ocean Color Sites

▪ NEON-Core Aquatic Sites

▪ LTER (Long Term Ecological Research)

▪ Research Cruises

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Information is being collected for each potential target site▪ Location and size

▪ Acquisition requirement (cloud fraction, solar angle)

▪ Time of operation or Season

▪ Instrumentation

▪ Additional Users

Users in the land and water calibration/ validation communities are being asked to review and refine the calibration sites▪ Providing additional information and prioritizing targets

Jack.Ickes@Teledyne.com mpagnutti@i2rcorp.com

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Jack Ickes Mary Pagnutti