CHRIS (Compact High Resolution Imaging Spectrometer) sira group sira electro-optics Dr Mike Cutter...
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Transcript of CHRIS (Compact High Resolution Imaging Spectrometer) sira group sira electro-optics Dr Mike Cutter...
CHRIS (Compact High Resolution
Imaging Spectrometer)
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Dr Mike Cutter
EO & Technology Business Manager
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CHRIS/PROBA – low cost mission CHRIS
Design concept - programmable hyperspectral Spectral range - VNIR Spatial sampling - 17 m @ perigee
PROBA Platform Small satellite (100kg) – launched October 2001 Agile 3-axis stabilised platform - roll, pitch & yaw Provides multi-angle observations & motion compensation
Mission Objectives Obtain selected land and littoral images Obtain multi-view angle measurements (aerosols, BRDF) Evaluate in-orbit performance - precursor mission
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Scene Radiance Information
The radiance field is at least 7 dimensional
( v, s ,, , x, y, t )
Angular(BRDF)
SpatialInformation
TemporalInformation
SpectralInformation
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MVA Data from CHRIS/PROBA
PROBA: Along-track: five angles
per overpass: 0°36, 55 @ ground
MVA = Multi-View Angle
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Day n+y
MVA data from CHRIS/PROBA
Day n+x
Day n
By rolling the satellite ± 25º in the across-track direction it is possible to image a fixed point on the Earth surface at different sensor view angles.
MVA = Multi-View Angle
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Information from MVA ImageLeft: Nadir-view, multispectral composite (0.5µm, 0.65 µm and 0.85 µm) showing wheat (red), bare soil (blue) and oil seed rape (white).
Right: Multi-angle composites (nadir + two oblique angles) at recorded 0.5 µm, 0.65 µm and 0.85 µm, respectively.
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Instrument Design
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CHRIS
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Specification
Image area 13 km square @ perigee
Spatial sampling interval 17 m @ perigee
Spectral range (nominal) 415nm to 1050nm
Spectral resolution 1.25 to 11nm
Spectral/Spatial registration +/- 0.05 pixel
Gain stage 4 levels (albedo 0.5,1,2,4 levels)
Digitisation 12 bits
Signal-to-noise ratio 200 (@ 0.2 albedo, 17m, 10nm)
Data per (13x13 km2) image 16.4Mbytes
Mass/power < 14 kg/ 10 W primary power
Volume 790 x 260 x 200 mm3
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GSD/band number options
Description Across-track
GSD Along-track
GSD Spectral bands
Full swath 17x17m 17m 17m 18 + 1 Full swath 34x17m 34m 17m 27 + 1 Full swath 34x34m 34m 34m 61 + 1 Half swath 17x17m 17m 17m 38 + 1 Half swath 34x17m 34m 17m 52 + 1 Half swath 34x34m 34m 34m 117 + 1
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Platform Aspects
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Platform Aspects Platform - ESA PROBA (Verhaert, Belgium)
Orbit 570- 730 km, sun-synch. (10.30am node) Inclination 97.97º, Repeat period 11 days Dimensions 800mm x 600mm x 600mm Power/mass < 100 W/100 kg
Pointing Along-track 0 º, +/- 36º, +/-55º (@ ground) Across-track +/-25º (@ ground) Absolute pitch/roll/yaw < +/- 0.1º Control of pitch/roll/yaw < +/- 0.015º/s (11% of imaging pitch rate) Maximum pitch rate 0.7º/s
Down-link S-band: 1 Mbit/s (5 images/day)
Ground Station Redu, Belgium
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Observation Plan
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Observation Programme Programme defined by CHRIS Steering Group (UK, ESA) AO issued by ESA in 2000 for first year mission. Observations
21 Core sites, 31 additional sites, 12 reserve sites Approx. 60 PIs world wide
Observation modes (5 off) excluding calibration Mode 1: Low resolution – aerosols, 62 bands Mode 2: High resolution – water, 18 bands Mode 3: High resolution – land, 18 bands Mode 4: High resolution – chlorophyll, 18 bands Mode 5: Half swath/high resolution – land, 37 bands
Observation logistics Apply 48 hour cloud predictions to aid target selection
Details: WWW.PROBA-CHRIS.ORG.UK
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Location of CHRIS Test Sites
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Sample Images
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Antwerpen
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Satellite Pitch Rates
Spectral0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 2500.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0.1
0.2
0.3
0.4
pitch rateroll rate x 10
seconds
degrees/s and 10 x degrees/s
.4
.9
.Pt
Pt 1
57.3
.Rt
Rt 1
573
2500 t
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New York
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Current Status
Platform Commissioning Platform undergoing fine tuning wrt pointing Platform processor intermittent issue being investigated Reviewing options for improving operational approach
Instrument Commissioning Instrument performance assessment on-going Data processing being validated for each imaging mode Wavelength calibration (O2 line) results being evaluated
Downlink Platform commanding approach being refined. Reviewing options for utilising a Kiruna (polar) downlink.
Data sets Plan to issue sample data sets to PIs in August 2002
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Acknowledgements BNSC for partial funding of CHRIS
ESA for the launch opportunity, support for calibration activities, data processing, the planning tool and website.
Redu, ESOC (Belgium) for operational support
Verhaert (Belgium) for platform support
RSAC (UK) for preparation of the planning tool & jointly with ESSC the CHRIS website.
UK PIs: Prof. Mike Barnsley (BRDF), Swansea University
Dr Jeff Settle (Aerosols), ESSC, Reading University
Dr Samantha Lavender (Coastal), Plymouth University
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The End
WWW.PROBA-CHRIS.ORG.UK