CHRIS (Compact High Resolution Imaging Spectrometer) sira group sira electro-optics Dr Mike Cutter...

CHRIS (Compact High Resolution

Imaging Spectrometer)

siragroup

siraelectro-optics

Dr Mike Cutter

EO & Technology Business Manager

siragroup siraelectro-optics

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


Scene Radiance Information

The radiance field is at least 7 dimensional

( v, s ,, , x, y, t )

Angular(BRDF)

SpatialInformation

TemporalInformation

SpectralInformation


MVA Data from CHRIS/PROBA

PROBA: Along-track: five angles

per overpass: 0°36, 55 @ ground

MVA = Multi-View Angle


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


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.


Instrument Design


CHRIS


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


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


Platform Aspects


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


Observation Plan


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


Location of CHRIS Test Sites


Sample Images


Antwerpen


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


New York


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


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


The End

WWW.PROBA-CHRIS.ORG.UK

CHRIS (Compact High Resolution Imaging Spectrometer) sira group sira electro-optics Dr Mike Cutter...

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