esa's activities in space-borne imaging spectroscopy...
TRANSCRIPT
CHII, 15-16 June 2016, Graz, Austria
Michael Rast, ESA
ESA's activities in space-borne
Imaging Spectroscopy for Earth
Observation
Observation Principle of Imaging Spectrometer
• The telescope images the ground scene on
the entrance slit
• The slit projection on ground defines the
swath width in across-track (ACT) direction
• The light is spectrally dispersed by a
diffraction grating and imaged onto a 2D
array detector
• Detector pixels represent image elements
sampled spatially in the ACT and spectrally
in the ALT
• Satellite motion during integration time
provides spatial sampling in along-track
(ALT) direction
Telescope
Slit
Collimator
Grating
Imager
2D detector
x
Spectral radiance
l
l
Spectral channels
Three-dimensional
hypercube
• Three-dimensional hypercube is assembled
by “stacking” two-dimensional spatial images,
each corresponding to a particular narrow
spectra channel
Courtesy R.Green, JPL
Future spaceborne imaging spectroscopy EO
missions – Launch and life time
ESA
28 29 30
EnMAP
PRISMA
HISUI / ISS
GISAT
FLORIS
Sentinel-3A
Shalom
CCRSS
Resurs-P No.4
Resurs-P No.5
ECOSTRESS
HySpecIQ
CartoSat-3
HYPXIM-P
2000 01 02
University of Hawaii, USA
Roscosmos, Russia
Sentinel-2A
… 14 15 16 17 18 19 20
HiakaSat
Resurs-P No.3
21 22 23 24 25 26 27
China
Roscosmos, Russia
ASI, Italy
ISRO, India
Roscosmos, Russia
JPL, USA
HySpecIQ/ Boeing, USA
ISRO, India
DLR, Germany
JAXA, Japan
ASI, Italy/ISA, Israel
ESA, UK
CNES, France
NASA/JPL, USA
DLR, Germany/ Teledyne, USA DESIS
HyspIRI
ESA Earth Observation Programmes
1980
1990
2000
2010
2020
sentinel-1
sentinel-2
sentinel-3
sentinel-5p
sentinel-4
sentinel-5
sentinel-6 jason-cs
envisat
earthcare
ers-1 ers-2
goce smos
cryosat swarm
biomass
flex
adm-aeolus
msg-1
meteosat-1
meteosat-2
meteosat-4
meteosat-3
meteosat-5
meteosat-6
msg-2 metop-a
metop-c
metop-b
msg-4
msg-3
metop-sg mtg-i
mtg-s
meteosat-7
Imaging spectrometer
Slide 5 IPD-HO-ESA-516 FLEX - J.-L. Bézy - ESA Space Technology Workshop, 14 APR 2016
Imaging Spectrometers in ESA E.O. Missions
dl:1.5-10 nm Radiom. Error ≈1 %
dl:0.1-0.5 nm Radiom. Error ≈ 0.1 %
(2021 -)
Earth Explorer 8: FLEX Mission Objectives
by direct measurements of vegetation fluorescence at
relevant spatial scales
FLEX will quantify actual photosynthetic activity of terrestrial ecosystems
FLEX will provide physiological indicators for vegetation health status
O2A O2B
Fluorescence Signal
The FLEX mission will accommodate an imaging spectrometer with a very high spectral-resolution (0.1 nm), to measure fluorescence within two oxygen bands, a second spectrometer to derive additional atmosphere and vegetation parameters
FLEX Mission: provide fluorescence emitted with 10% accuracy
FLEX: Low and High Resolution Spectrometers
FLEX/Sentinel-3 Formation Flying for Vegetation Health
/ FLEX FLEX: Global estimates of the actual
photosynthetic activity at the field scale
Pests
Elevated CO2
Salinity
Insecticides
Herbicides
Nutrient deficit
Pollutants
Acid rain
UV
Ozone
High light
Heat
Freezing Chilling Water deficit
Photosynthetic Strain
Weeds
Heavy metal
toxicity
FLEX Driving Observation Requirements
Requirement Specification Comment
Swath width 150 km Optical design
Spatial Sampling Distance 300 m Same as OLCI
Spectral band coverage 500 nm – 780 nm
Spectral Resolution 0.3 nm (HR) – 2 nm (LR) HR: High Resolution
LR: Low Resolution
Spectral Sampling 0.1 nm (HR) – 0.65 nm (LR)
ISRF knowledge 1% Stable opto/mechanical concept
On ground characterisation
Signal to noise ratio > 115 at 761 nm
Pupil size (80 mm), mass and
volume
Efficient detector & gratings
Straylight sensitivity 1% (Level 0)
Low roughness of optical surface
Low level of PAC Contamination
On ground characterisation
Spectral co-registration <0.1 SSI Good optical design with low smile
and keystone
Accurate alignment of detector Spatial co-registration <0.1 SSD
Absolute radiometric
accuracy 5 %
On board calibration device
On ground characterisation
Polarisation sensitivity < 1% Polarisation Scrambler
Enabling “Technology” for Imaging spectrometer
• Large 2D detectors
• Gratings with high efficiency, low sensitivity to
polarisation and low straylight level
• Optics with low level of straylight
Low surface roughness
Low PAC contamination level
• Spectrometer slit (planar or 1D homogenizer)
• Efficient polarisation scrambler
• Accurate on ground calibration (straylight, spectral
response function)
Imaging Spectrometers in Future EO Programme
Operational European carbon
dioxide (CO2) mission
Earth Explorer 9
• 31 letters of intent received
• 9 missions proposed with
imaging spectrometer
International Cooperation
EnMAP Flight Model on Ground Support Equipment Sept. 2015
NASA CWIS F/1.8 VSWIR Imaging Spectrometer
Technology development – way forward
Imaging spectrometers for future E.O. missions are relying on cutting-
edge technology
Technology development shall not only address key instrument components (detectors, gratings, ..) but also efficient OGSE for on-ground calibration
Enabling technology for future imaging spectrometers have been well
captured in the TRP 2016-2017 Work Plan
Straylight characterisation
Straylight characterisation
ISRF characterisation
Straylight mitigation
Straylight mitigation
Large format detector for (e.g.) CO2 mission
Images can raise many questions spectra can answer them -Rob Green
Conclusion
Thank you for your attention