EarthCARE Optical Instruments In Orbit
Characterisation, Calibration and Verification
2nd ESA EarthCARE Validation Workshop
Kotska Wallace, Mission and Optical Payload Manager
25-May-2021 (online)
ESA UNCLASSIFIED – For ESA Official Use Only

1

ContentOverview of in orbit commissioning activities
BBR calibration concept
BBR IOCVMSI calibration concept
MSI IOCV[ ATLID → See following presentation from Georgios Tzeremes.]

EarthCARE optical instruments in-orbit characterisation, calibration and verification - 2nd ESA EarthCARE Validation Workshop– Webex | 25 May 2021 | Slide 2Overview of in-orbit commissioning activities
EarthCARE commissioning phase 6 months, ending with In-Orbit Commissioning Review (IOCR):•

Achieve final reference orbit.

•

Complete platform functional verification, health checks, instruments switch-on & decontamination.

•

Verification of ground segment (interfaces, data flow, processing, archiving, mission planning).

•Instruments in-orbit characterisation, calibration and in-orbit performance verification.
•

Instrument health, function, calibrations, optimisation of settings and verification of expected performance.
••(Limited to nominal instrument side, i.e. no redundancy check out.)•Check of instrument co-registration using land marks or terrain elevations.

•Product verification (i.e. consistency checks etc., not using external correlative data.)•L1 algorithms by industry and any processor updates implemented by ESA.

•

L2 algorithms by L2 expert teams.

Teams at ESA (Project, Flight Operations Segment, Payload and Data Ground Segment), JAXA
Ground Segment, Industry Satellite and Instrument Teams, Validation Teams, ECMWF
EarthCARE optical instruments in-orbit characterisation, calibration and verification - 2nd ESA EarthCARE Validation Workshop– Webex | 25 May 2021 | Slide 3

Overview of IOCV activities - indicative timeline•

Validation of data products and processing algorithms is initiated during the commissioning phase•

1st product releases for each of the 4 instruments in coordination with ESA project, mission
management & JAXA (individual products, followed later by multiple products view of same scene)
EarthCARE optical instruments in-orbit characterisation, calibration and verification - 2nd ESA EarthCARE Validation Workshop– Webex | 25 May 2021 | Slide 4

Overview of IOCV activities - instruments timeline

EarthCARE optical instruments in-orbit characterisation, calibration and verification - 2nd ESA EarthCARE Validation Workshop– Webex | 25 May 2021 | Slide 5

BBR calibration concept
LW and SW data from 3 telescopes; LW data retrieved via subtraction of SW from TW channel.
•Requires knowledge of the instrument and scene spectral response.
•Unfiltering can be enhanced with use of MSI data to improved the scene spectral correction factor

BBR calibration approach:• TW: Two point calibration using hot & cold blackbodies•Performed on-board automatically, every 90 s, for removal ofsignals offset (instrument self emission) & gain determination.

• SW: SW aging data from solar illuminated diffusor.
•Collected over 30 orbits, every 2 months.

•Monitor Photo Diodes in the telescope baffles assess aging of thediffuser and filter.

•L1B products used to plot SW gain ratio, LW spectral correction
factor and filter transmission for expert assessment of any need
to update CCDB parameters (review every 6 months)
EarthCARE optical instruments in-orbit characterisation, calibration and verification - 2nd ESA EarthCARE Validation Workshop– Webex | 25 May 2021 | Slide 6

BBR IOCV concept
During Commissioning:•

Switch on, decontamination (12 hr), health status check (telemetry in limits), functional check (modechanges, mechanism movements etc.)•

Detector raw data check (comparison of raw mode and processed output in the instrument ISP toverify on-board DSP.)•LW performance check from standard L1b data product (gain, LW radiance noise, gain stability).
••

SW calibration collects data for in-flight reference and any update of calibration parameters••

Possible updates to blackbody power, calibration interval.
Performance check compares data against Visible Calibration (VisCal) system on-ground reference
characterization and calibration 2 months later (MPD noise and collection of in-flight aging reference SW
gain ratio, LW spectral correction factor and filter transmission)

Detector linearity check via swap of powers to hot and cold BBs over several hours with instrument
continuous operation•

Repeated 6 monthly, although no linearity change is expected
EarthCARE optical instruments in-orbit characterisation, calibration and verification - 2nd ESA EarthCARE Validation Workshop– Webex | 25 May 2021 | Slide 7

BBR key calibration parameters
measuredpre-flightmeasuredin-flightapplied in-flight

Data frequency

SW gain ratio, BüDerived from
BBR_SOL_1B

ü CCDB

Collect 2 mo,assess 6 mo

LW spectral correction factor, Aü

Derived from
BBR_SOL_1B

ü CCDB

Collect 2 mo,assess 6 mo

SW filter transmission, <! > #$ü

Derived from
BBR_SOL_1B

ü CCDB

Collect 2 mo,assess 6 mo

BBR_LIN_1B

ü CCDB

6 mo

Detector linearity

ü

Detector gain, GLWüDerived from
BBR_LIN_1B

ü CCDB

90 s

TW calibration intervalüDerived from
BBR_LIN_1BOn-board

90 sOffset and gain stability

üDerived from
BBR_LIN_1B

ü CCDB

90 s

MPD noiseü

BBR_SOL_1B

ü CCDBCollect 2 mo,assess 6 moEarthCARE optical instruments in-orbit characterisation, calibration and verification - 2nd ESA EarthCARE Validation Workshop– Webex | 25 May 2021 | Slide 8

MSI calibration concept – VNS camera
Pushbroom onto 4 detectors, calibration of data to radiance units.
••

One SWIR-2 aperture and a second aperture for Visible, NIR and SWIR-1 channels.

Daily two point calibration against a solar illuminated diffusor and the closed shutter.
•Closed shutter to collect dark signal, in order to characterise detector fixed pattern offset & noise; generated
flat field will be activated and subsequently applied automatically on-board.

•Daily bright scene calibration using one pair of solar
illuminated diffusors in front of the two camera apertures(data monitored to track performance degradation.)•Monthly diffusor pair used to monitor degradation of thediffusors (data to correct long term drift in diffusorperformance.)•Specific L1b calibration data products generated formonitoring.
EarthCARE optical instruments in-orbit characterisation, calibration and verification - 2nd ESA EarthCARE Validation Workshop– Webex | 25 May 2021 | Slide 9

MSI calibration concept – TIR camera
Pushbroom with 3 channels dispersed onto a single detector, calibration of data to brightness
temperature.
•Increases sensitivity using 19 rows of Time Delay Integration, applied automatically on-board.

•A 4th reference channel collects data from a detector view of theinternal optics, which the ground processor averages & subtracts
from scene channel signals to correct for thermal drift & detector
noise.

• Daily two point calibration against the cold scene and aninternal blackbody.
•TIR views the cold space port to characterise the detector fixedpattern offset and noise; flat field generated will be activated andsubsequently applied automatically on-board.

•TIR views the internal blackbody to monitor sensitivity changes.

• Specific L1b calibration data products generated for monitoring.
EarthCARE optical instruments in-orbit characterisation, calibration and verification - 2nd ESA EarthCARE Validation Workshop– Webex | 25 May 2021 | Slide 10

MSI IOCV concept
During Commissioning:•

Switch on, decontamination (30 days), health status check (telemetry in limits), functional check(mode changes, Active Thermal Control, mechanism movements etc.)•Calibrations collect and apply VNS and TIR flat fields.

•TIR raw mode operation to collect reference in-flight TIR detector pixel map (no TDI.)•VNS performance check from standard L1b data products and collection of in-flight reference(detector characteristics, diffusor references).

•TIR performance check from standard L1b data products and collection of in-flight reference data(detector characteristics, checks for sensitivity to detector temperature and bias voltages, relay lenstemperature, bench and case temperature, cold space mirror self emission)

EarthCARE optical instruments in-orbit characterisation, calibration and verification - 2nd ESA EarthCARE Validation Workshop– Webex | 25 May 2021 | Slide 11

MSI key calibration parametersmeasured
pre-flightmeasured
in-flight

applied inflight

Datafrequency

üStored in ICU

On-board
via TCdaily

ü

MSI_SD2_1B, MSI_SD1_1B

ü CCDBdaily,monthly

ü

MSI_DRK_1B

ü CCDBdaily

ü

MSI_BBS_1B

ü CCDBdaily

ü

MSI_TRF_1B

ü CCDBdaily

TIR cold space mirror offset

ü

TIR_CSM_OFFSETü CCDB

daily

Gain corrections; TIR, VNSü

TIR_GAIN_CORR,
VNS_RAD_CORR

ü CCDBdaily

Flat fields; TIR, VNS
VNS diffusor datasets daily, monthly;
detector noise, responsivity

VNS closed shutter datasets; flat field, image
statistics

TIR calibration products BB & CS views;
detector noise, responsivity, flat field

TIR sensitivity; detector bias V, detector temp.,
relay lens temp., bench temp., case temp.

EarthCARE optical instruments in-orbit characterisation, calibration and verification - 2nd ESA EarthCARE Validation Workshop– Webex | 25 May 2021 | Slide 12

ATLID calibration concept and IOCVà See presentation of Georgios Tzeremes
Thank you for your attention.

MSI TIR BBQuestions?

EarthCARE optical instruments in-orbit characterisation, calibration and verification - 2nd ESA EarthCARE Validation Workshop– Webex | 25 May 2021 | Slide 13