APEX - Airborne Prism EXperiment Walter Debruyn Vito/TAP Boeretang 200 B-2400 Mol [email protected] .

APEX - Airborne Prism EXperiment

Walter Debruyn

Vito/TAP

Boeretang 200

B-2400 Mol

[email protected]

http://www.apex-esa.org

Scope of APEX

APEX is a hyperspectral airborne simulator for the support and development of future hyperspectral spaceborne missions.

APEX will be able to Simulate, Calibrate, and Validate

the planned European imaging spectrometer missions (ESA Land Mission, CHRIS/PROBA, MERIS/ENVISAT).

APEX will foster the use of imaging spectrometer data in Europe and will support the application development of imaging spectroscopy products.

APEX is the first European perspective of an imaging spectrometer covering the full solar reflected range.

APEX in the Context of ESA

Partial Simulation Capabilities Only

Earth ExplorerMission(s)

LSPIM (Phase A)

TechnologyDemonstrator

Science Demonstrator& Data Simulator

CHRIS on PROBA

Further advancementof the Land Mission

New Land Mission Radiometric Transfer Standard(MERIS, CHRIS, etc.)

Co–Investigator

APEX Setup (Phase B)

Belgian PRODEXOffice

Swiss PRODEXOffice

TechnicalDirectorate

Earth Observation

PRODEXOffice

Principal Investigator

Scientific ConsultancyGroup (SCG)

Swiss PRODEXCommittee (PPK)

Industrial Prime

IndustrialSubcontr.

IndustrialConsultant

IndustrialSubcontr.

Industrial Con-sultant

National Entities Institutes Industry

Alcatel Space

France

DSS–OIP

Belgium

Alcatel Space

Switzerland

SF

Switzerland

DLR / DFD

Germany

APEX Timeline

Pre–Phase A

Phase A

Phase B

Phase C/D

Phase E

Post–Phase E

Feasibility Studyof APIS and

AMIRIS

1/96 7/96 8/96 2/98 10/98 3/00 4/01(?) 6/03(?) 6/03 6/08 6/13

Feasibility Studyof APEX and

Critical DesignReview (CCN2) Detail Specifica-

tions andBreadboards

HardwareConstruction

and Implementation ESA Operation

and Exploitation

APEX Optimization Scheme

Optimization Priorities Signal to noise,

Transmission of optical design Pushbroom principle Minimizing noise of detectors and electronics

Spectral uniformity, Coregistration of spectral channels and bands Minimizing geometric abberation (‘frown’ and ‘smile’)

Stability, and Pressure/temperature controlled environment Pre and post flight on board calibration

Repeatability. Laboratory and vicarious calibration Navigational system (Positional and attitude recording system)

APEX Specifications (1 of 2)

Parameter Requirement

Field of View (FOV) ± 14 deg

Instantaneous Field of View (IFOV) 0.5 mrad

Flight altitude 4,000 - 10,000 m.a.s.l. (7,500 m nominal)

Spectral channels VIS/NIR: 124; SWIR: 176

Spectral range 400 – 2500 nm

Spectral sampling interval 600 – 780 nm: < 5 nm400 – 600 nm and 780 – 1050 nm: < 10 nm; optimized for SNR

1050 – 2500 nm: < 10 nm

Spectral sampling width < 1.5 * Spectral sampling interval

Center wavelength accuracy < 0.2 nm

Spectral sampling width accuracy < 0.02 * Spectral sampling width

PSF (Point Spread Function) PSF 1.75 * IFOV

Smile < 0.1 pixel

Frown < 0.1 pixel

APEX Specifications (2 of 2)

Parameter Requirement

Bad pixels None (requirement after electronics)

Scanning mechanism Pushbroom

Absolute radiometric calibration accuracy 2%

Storage capacity on board (online) > 50 GByte

Dynamic Range 16 bit

Positional knowledge 20% of the ground pixel size (DGPS required)

Attitude knowledge 20% of IFOV (accelerometers, gyros, inertial navigation system required)

Navigation system, flight line repeatability ± 5% of FOV

Positional and attitude data Recording of data onto a housekeeping channel

Reliability 99 % successful data acquisitions for all flights during each year of operation

Optical head dimensions Must fit in standard mount

Signal To Noise Levels

Simulated APEX Spectral Response

APEX - Airborne Prism Experiment

APEX BlockdiagramAircraft

Processing and Archiving Facility

Data Storage Preprocessing

Processing Data Distribution

Stabilized Platform

Laboratory Calibration

Detector / FEE

Video Electronic Unit

SW

IR

De

tecto

r / F

EEVIS

Op

tom

ech

an

. Pa

rt

Data Recording System: Framegrabber Unit User Interface Unit

Monitoring Unit Power Supply

DGPS

INS

Calibration Means

Protective Window

Net- work

FOV

Gro

un

d

Ima

ge

r

Processing and Archiving Facility

Data storagePre-processing

ProcessingData Distribution

APEX raw data simulation

Simulated raw sensor data as acquired by the APEX system, including dark current and internal integrating sphere measurements. This cube contains all data acquired for one imaging section (simulation based on HYMAP measurements).

The PAF Processing Levels

data download and segregation

Level 2B/C

orthorectification

system correctioncalibration

linking parameters: view angle, view distance, terrain height

atmospheric andradiometric correction

Level 1D

Level 2A

Level 0B

Level 3

laboratory and in-flightcalibration data

in-flight auxiliary data

DEM, flightpath

meteorological measurements

application processing

APEX (near) future

Phase C/D operational organization- Scientific Team : RSL- Operations Team : Vito

2000 : Calibration test site studied :

HYMAP and CASI flight campaigns

2001: AVIRIS flight campaigns throughout Europe

(ESA initiative, Vito operations)

APEX Outlook

Completing the - instrument

- processing and archiving facility

- calibration home base

in Spring 2003 is achievable

Additional ESA study (detectors, calibration) [institutes]and breadboarding of critical components [industry]are ongoing

Hardware construction and implementation (phase C/D) will start ASAP