IASI-NG : CNES phase 0 study presentation...2nd IASI conference; Annecy, January 2010 3 IASI-NG performance objective Improve the IASI demonstrated performances : Spectral Resolution

IASI-NG :

CNES phase 0 study presentation

2nd IASI conference

Annecy, January 2010

M. Albinet, B. Belon, F. Bernard, D. Blumstein, L. Buffet, C. Buil, L. Cadiergues,

P. Guay, P. Hebert, T. Maciaszek, E. Pequignot, C. Pierangelo, M. Saccoccio,

C. Serieys, T. Phulpin, T. Tirolien

2nd IASI conference; Annecy, January 2010 2

Content

1- IASI-NG performance objective and compliance with the EUMETSAT

POST-EPS IRS Mission Requirement Doc

2- IASI-NG CNES phase 0 technical synthesis

3- IASI-NG CNES phase 0 expected performances and budgets

4- IASI lessons learned from technical point of view

5- IASI-NG activities in 2010


IASI-NG performance objective

■ Improve the IASI demonstrated performances :

Spectral Resolution by factor 2

Radiometric noise by factor 2

==> comparable to Post-EPS MRD 2.E breakthrough data

■ Keep the same spatial resolution as IASI (25km in average on ground at nadir) and the same IASI pixel size (12km)

■ Compliance of the IASI-NG specification to Post-EPS IRS requirements presented to PMET end of 2009.Main non compliances with MRD 2.E:

Viewing angle and coverage (will be the IASI one for IASI-NG)

Pointing knowledge (will be just a bit better than the IASI one)

Radiometric noise below 645cm-1 and above 2400cm-1

Accepted by PMET : MRD to be updated


IASI-NG performance objective versus Post EPS MRD

Spectral resolution (level 1b)

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

500 700 900 1100 1300 1500 1700 1900 2100 2300 2500 2700 (cm-1)

Sp

ectr

al

reso

luti

on

(cm

-1)

IASI-NG SPEC level 0

MRD NWP breakthrough V2.E

MRD CHEM breakthrough V2.E

IRS1 :

Temp

Profile

IRS2 :

Temp & Water

vapour profiles,

surf & cloud

IRS

3 :

O3

co

lIR

S3

a :

O

3 p

rof

IRS

4 :

su

rf &

clo

ud

IRS5 :

Water vapour profile

IRS6 :


NO2 Column

IRS

8 :

T p

rofile

,

N2O

& C

O2

co

l

IRS9 :

Temp

profile

IRS10 :

SST, surfaces and

cloud properties

IRS

5b

:

T p

rofile

, N

2O

& C

H4

co

l

IRS

2a

:

C2

H6

IRS

2b

:

HN

O3

, C

FC

IRS

4a

:

SO

2IR

S4

b :

PA

N

IRS0 :

Water

vap

Prof IRS

7 : C

O c

ol

IRS

7a

: C

O p

rofile

IRS11

CH4

col

NWP

Pri 1

MWP or

Chem

Pri >=2

Chem

Pri 1

Priority

SPEC IASI-NG With Self-

Apodisation

OPD CHEM=4cm OPD CHEM=4cm SPEC CHEM without Self-

apodisation (0,6/OPD)

SPEC NWP With Self-

Apodisation


IASI-NG performance objective versus Post EPS MRD

RADIOMETRIC NOISE @280K (Level 1b)

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

500 700 900 1100 1300 1500 1700 1900 2100 2300 2500 2700 (cm-1)

Ned

T @

280K

(K

)

IASI / 2 (sample 0.25cm-1)

IASI-NG SPEC (sample 0.125cm-1)

MRD CHEM Breakthrough V2.E

MRD NWP Breakthrough V2.E

IRS1 :

Temp

Profile

IRS2 :

Temp & Water

vapour profiles,

surf & cloud

IRS

3 :

O3 c

ol

IRS

3a :

O

3 p

rof

IRS

4 :

surf

& c

loud

IRS5 :


IRS6 :


NO2 Column

IRS

8 :

T p

rofile

,

N2O

& C

O2 c

ol

IRS9 :

Temp

profile

IRS10 :

SST, surfaces and

cloud properties

IRS

5b :

T p

rofile

, N

2O

& C

H4 c

ol

IRS

2a :

C

2H

2,

HC

N,

PA

N

IRS

2b :

H

NO

3,

CF

C

IRS

4a :

S

O2

IRS

4b :

PA

N

IRS0 :

Water

vap

Prof IRS

7 : C

O c

ol

IRS

7a :

CO

pro

file

IRS11

CH4

col

NWP

Pri 1

MWP or

Chem

Pri >=2

Chem

Pri 1

Priority


IASI-NG : radiometric and spectral improvements

•Entrance pupil diameter Increase (flux):

IASI-NG = 120mm versus IASI = 80 mm

•Instrument Field of view Increase (integration time):

IASI-NG = 75*75km (9 pixels) versus

IASI = 50*50km (4 pixels) acquisition duration

for each interferogram = 450ms versus 150ms for

IASI

•Detectors temperature reduction (active cooling)

IASI-NG T detector < 65K versus IASI = 92K

Radiometry

Optical Path difference increase by factor 2:

• single sided interferometer

• one mobile cube having the same IASI stroke

• TWO mobile cubes having the IASI stroke / 2

• double sided interferometer

• one mobile cubes having the IASI stroke x 2

• TWO mobile cubes having the same IASI stroke

Spectral resolution

50 km

17 km

BUT: «self-apodisation»

For the spectral resolution, both the

Optical Path Difference AND the self-

apodisation must be improved.50 km

17 km

IASI

33 km

25 k

m

Different trade off’s done only for dynamic FTS

IASI-NG


IASI-NG : the self-apodisation issue

Sounder pixel

• For each of the 9 sounding pixel, acquisition of sub-

pixels interferograms (typically 5x5 sub-pixels), then

combination of the interferograms by resampling at

“constant” OPD + filtering to generate one sounding pixel

interferogram

•Final Self-apodisation for the corner pixels = IASI one

Huge Data Processing (1Gbit/s of

data at the matrix output)

IASI-NG: Optical signal in the

detectors plane for n=2760cm-1

and OPDmax=4cm

Need a very GOOD focal

plane image quality

complex focal plane

Split the sounder pixel into many smaller pixels

Matrix detectorsSuppress/mitigate the self-apodisation effect

self-apodisation compensation

•Introduce, in the interferometer, a specific

mechanism that works in synchronization with

the Corner Cube Mechanism and that corrects,

for each sounding pixel (but the center one),

the Optical Path Difference by :

dO (1 – cos q), where dO is the OPD for a zero

field ALL the pixels should have a

similar behavior than the central pixel

q

IASI-NG CNES Phase 0

Reference option

The use of IASI like pixel acquisition concept is not possible. Two options has been studied.


IASI-NG : Self-Apodisation compensation option

Direct acquisition of one interferogram by

sounder pixel using monoelement pixel

detectors (IASI like) or by matrix detectors with

hardware binning of the elementary pixels

New Genzel concept

Evolution of a corner pixel

optical signal for

monochromatic ray at

4mm, for OPD variation of

1mm, (between max and

min signal (l/4)) at OPD of

4cm

Without compensation

With compensation

OP

D e

volu

tio

n

Without compensation

With compensation

Optical simulation with and without active optical field compensation

Advantages

Drawbacks

New mechanism

OPD (cm)

CO

NTR

AST

Data processing IASI like (excepted for the

single sided processing)

IASI like cold optical focal plane

Reduction of the different defaults sensitivity

with regard to IASI (CCM, microvib’s)

Complexification of the

Laser Reference

accommodation


Ground Pixel diameter of 12km (=IASI)

Ground sampling of 25km (both axis)

Number of sounder pixels per acquisition = 9 (IASI=4)

Number of earth view per line = 20 (30 IASI)

Interferogram acquisition duration = 450ms (IASI=150ms)

Inlet PUPIL = 120mm (IASI=80mm)

Focal plane :

4 bands (IASI=3)

9 sounder pixels per band (IASI=4)

PV detectors for all bands

(IASI PC for B1; PV for B2/B3)

detectors cooled at 65K with

one active cooler (LPTC)

(IASI=92K passive)

IASI like cold optic concept

IASI-NG : Baseline characteristics (CNES phase 0)


IASI like SCAN with slight increase of

the motorization

One afocal telescope

One GENZEL interferometer

1 ZnSe Beam Splitter (80mm typical)

Single sided configuration

(to be justified more deeply)

2 Corner Cubes are linked together

and are activated by a single

mechanism (CCM) with a stroke of

11mm (IASI=20mm for one CC)

1 field compensation mechanism

One laser beam for OPD sampling

for each pixel



Genzel interferometer :

Mechanism for field compensation

9 individual independent flat mirrors. 8

mirrors are mobile. The central one is not

moving.

Each individual mirror is activated in

rotation by one independent piezzo in

coordination with the Corner Cube

Mechanism (the mirror on the center is

not moving) :

– OPD=0 No rotation; all the mirrors are in

the same plane

– OPD max maximum rotation of typically

1.5mrad

A breadboard is under development at

CNES

Rotationaxis


OPD=0 OPD=4cm OPD=0


Data processing :

Earth precalibrated spectra are downloaded + IR image

DPS with high heritage of IASI for the algorithms excepted for the single sided

interferogram processing

LEON’s processor + FFT coprocessors (FFT of 65536 samples is done in 1ms)

Spacewire bus

IR integrated Imager :

IASI like with increased field of view

Instrument Management :

Classical with 1553 bus

Mechanical & thermal:

IASI-NG accommodation on the

satellite velocity face with access to

a second deep space calibration view



Mechanical & thermal:

Interferometer equipments are mounted on a stiff

CFRP optical bench

ALL the others panels are aluminum honeycomb

panels

ALL equipments, panels and baffles are controlled

at 293K (excepted the detectors at 65K)

No Launch Locking and microvibrations Filtering

Device



MASS

IASI-NG : 260Kg (best estimate without margin)

IASI = 235Kg

VOLUME

IASI-NG : 1700mm x 1400mm x 800mm in a single box (1,9m3)

Optimization can be envisaged

IASI : one sensor module + deported IMS/DPS inside the satellite ==>

total = 1,7m3

■POWER (EOL):

IASI-NG : 370W (best estimate without margin) (active cooling

main contributor)

IASI = 240W

■TM DATA RATE:

IASI-NG : 3.1Mbit/s

IASI : 1.5Mbit/s



IRS2 End of phase 0 CNES budget estimation; IRS2 SPECIFICATION

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

1,1

1,2

600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800

Sigma (cm-1)

Ned

T @

280K

(K

)

IRS2 SPEC IRS2 phase 0

IRS1 :

Temp

Profile

NedT @ 280K

IRS2 :

Temp & Water

vapour profiles,

surf & cloud

IRS

3 :

O3 c

ol

IRS

3a :

O

3 p

rof

IRS

4 :

surf

& c

loud

IRS5 :


IRS6 :


NO2 Column

IRS

8 :

T p

rofile

,

N2O

& C

O2 c

ol

IRS9 :

Temp

profile

IRS10 :

SST, surfaces and

cloud properties

IRS

5b :

T p

rofile

, N

2O

& C

H4 c

ol

IRS

2a :

C

2H

2,

HC

N,

PA

N

IRS

2b :

H

NO

3,

CF

C

IRS

4a :

S

O2

IRS

4b :

PA

N

IRS0 :

Water

vap

Prof IRS

7 : C

O c

ol

IRS

7a :

CO

pro

file

IRS11

CH4

col

NWP

Pri 1

MWP or

Chem

Pri >=2

Chem

Pri 1

Priority

IASI-NG Phase 0 instrument

Performance estimate

IASI-NG Phase A Requirement

Spectral resolution at level 1b = 0.15cm-1 almost constant all over the

spectral bandwidth. =0.25cm-1 at level 1c (after numerical apodisation)

Radiometric noise (level 0 for samples of 0.125cm-1):



IASI lessons learned applicable for IASI-NG

■ Engineering & AIT constraints improvements / IASI

Thanks to a very stiff interferometer :

The instrument performances should not be sensitive to gravity

The instrument performances should be much less sensitive to microvibrations

The corner cube compensation mechanism (<10Hz) should be

avoided (one main source of microvibration for IASI)

Thanks to an active cryocooler and a sealed cold box/focal plane:

the instrument should be able to cool the detectors by itself at ambient

cleanroom condition (Possibility to do representative EMC tests at ambient, ...)

No need of the quite complex IASI test jig and cryopannel for the satellite TV

tests

The ice contamination of the cold optics should be minimized

Can fly on any sun-synchronous orbit <10h30 and >13h30 with minor

modification on the warm thermal radiators


IASI configuration for TV test !!

IASI flight configuration



■ Engineering & AIT constraints improvements / IASI

Should avoid Locking and Filtering device no storage and

transportation constraints

The CCM locking/unlocking mechanism should be simplified

The instrument shall be able to be fully functional with the satellite in

vertical position and for one horizontal position

No deported equipments (IMS/DPS for IASI) inside the satellite

Easy accessibility to all of the equipments including the cold focal

plane should be possible

■ Operational improvements / IASI

The unavailability period due to ice decontamination should be

significantly reduced

Following an anomaly, the recovery time should be significantly

reduced



IASI-NG Phase A in 2010

A competitive industrial IASI-NG instrument phase A has

started with ASTRIUM and THALES beginning of 2010.

Both industries will evaluate the CNES phase 0 concept

AND some others ones. A concept selection will be done

before mid 2010 for more deep analysis studies.

The end of this IASI-NG phase A is expected for

beginning of 2011.

Discussion start with EUMETSAT about IASI-NG ground

segment

Documents

IASI-NG : CNES phase 0 study presentation...2nd IASI conference; Annecy, January 2010 3 IASI-NG performance objective Improve the IASI demonstrated performances : Spectral Resolution