1 COROT Science Week, Marseille, 3-6 June 2003 COROT mission Agenda ðSystem progress report §Scenario of observations §Satellite engineering Confirmation

1COROT Science Week, Marseille, 3-6 June 2003

COROT missionCOROT mission

Agenda System progress report

Scenario of observations Satellite engineering

Confirmation of the flight domain System engineering

Satellite-to-ground link

Telemetry budget Launch of COROT

Picture of SOYUZ in Kourou


Instrument progress reportInstrument progress report

COROTCASE

COROTEL

COROTLOG

COROTCAM

PROTEUS


System progress reportSystem progress report

Satellite engineering overview Many activities

Spacecraft mathematical modelfor coupled load analysis with the launcher

SED-16 star tracker accommodation AOCS specific command & control Mechanical and electrical interfaces

AOCS performances To be estimated after coupled simulation with payload ecartometry Results available for the next Corotweek (Marseille, spring 2003)

Spacecraft roll domain Power budget improved by Li-Ion battery Beginning of life : simulations show that the ± 20° requirement will be met End of Life (low electrical efficiency, broken cells) : performance TBC

Last step of the contract negotiation with Alcatel Contract to be signed in the first quarter of 2003



Orbit parameters The orbit will not be kept phased after commissioning

risk of sun glare in case of semi-major axis correction maneuver semi-major axis drift over 5 years : - 7 km (atmospheric drag) orbit period stability over 6 months : better than 1 s

Eclipse

Xs+

Thruster along Xs

Sun direction



Orientation of the satellite - flight domain

South

North

Orbit plane

Perpendicular to the orbit plane

boresightRoll angle

Sun



The sky observed by COROT

0°

30°

60°

90°

120°

150°

180°

210°

240°

270°

300°

330°

0h2h4h6h8h10h12h14h16h18h20h22h

SummerZone of observationcentered at 18h50

WinterZone of observationcentered at 6h50

Galaxy



Satellite design / axes

Zs+

Xs+

Ys+

Equipment bayUpper compartment with sensitive equipmentFine thermal regulation subsystem



Platform design “PROTEUS Evolution” family

series of 5 platforms upgraded electrical and AOCS chains

Li-Ion battery higher capacity (80 A h)

no more problem of power supply in Safe Hold Mode lower thermal dissipation

the battery sidewall can withstand any solar incidenceno need to rotate on the boresight axis after 5 months

New Magneto Torquer Bars higher capacity (180 A m2)

better convergence of the Safe Hold Mode equipment driven by a proportional control law

no more pointing disturbances due to MTB activations

Other features : new star trackers (SODERN), 2-antenna GPS



New mission schedule Thermal constraints shrunk to payload constraints

the Ys+ satellite wall (focal unit radiator) must be in the shadeas much as possible

No more 180° rotation on Xs between CP and EP No more EP2 critical thermal configuration for payload design Several possibilities for the scheduling

Exploratory Programs can be carried out either at the beginningor at the end of a 6-month period

an alternate schedule CP1, EP1, CP2, EP2 is operationally recommended

Focal unit radiator temperature worst cases in 1b and 2b 1b and 2b zones crossed by the Line of Equinoxes temperature depending on direction of observation and roll angle



Straylight Thermal constraints

polar caps lightened under small angles see the Corotweek n°3 (Liège) - presentation by Annie Baglin « scattered light from Earth »

the maximum is reached when the satellite flies over the day part of the Earth



Eclipses (over the year) max : 0.34 Torb

Eclipses à 826 km

0

500

1000

1500

2000

2500

0 1000 2000 3000 4000 5000 6000

numéro d'orbite

du

rée

to

tale

(s

ec

)

19/01 19/06 22/07 19/12

Favorable period of timeLow-level perturbations



Previous schedule“Peace and Love”

Line of nodes

Summer

Winter

Autumn

Solar declinationup to +23°

Ys+

Solar declinationdown to –23°

Central Program 2

Exploratory Programs 1 & 2

180° rotation on Zs

180° rotation on Xs

180° rotation on Xs


Satellite axesin a fixed orbital reference frame ROF

XJ2000

YJ2000

XOF

ZOF

Equatorial plane

12.5°

Earth orbit

Central Program 1

Line of Equinoxes

Spring

S

Xs+

Zs-

Xs+

Zs-

Ys+

Xs+

Zs-

Ys+

Zs-

Xs+ Ys+

Anticenter (6h50)Center (18h50)



Updated schedule“Piece of cake”

Line of nodes

Summer

Winter

Autumn



Central Program 2

Exploratory Programs 1 & 2




XJ2000

YJ2000

XOF

ZOF

Equatorial plane

12.5°

Earth orbit

Central Program 1

Line of Equinoxes

Spring

S

Xs+

Zs-

Ys+

Zs-

Xs+ Ys+

1b

1a 2b

2a

Center (18h50) Anticenter (6h50)



Line of nodes

Summer

Autumn


EP 1




XJ2000

YJ2000

Equatorial plane

12.5°

Earth orbit

CP 1

Line of Equinoxes

Spring

Zs-

Xs+ Ys+

1b

1a

18h50

Favorable directionin the observation cone

RA +

S



Line of nodes

Winter

Autumn


CP 2EP 2




XJ2000

YJ2000

Equatorial plane

12.5°

Earth orbit

Line of Equinoxes

Spring

Xs+

Zs-

Ys+

2b

2a

6h50

Favorable directionin the observation cone

RA +

S



Straylight maximum level (on the orbit) as a function of time

case of winter

-12° RA +12° RA

-12° dec

+12° dec



Performance management Performance management consists in choosing the most favorable edge for

each observing run a slight drop in periodic performances (compatible with the requirements) can be tolerated

for the EP observing runs white noise bphot = f(1/ Tobs) in Fourier space

spectrum analysis less sensitive to periodicperturbations (hidden lines) in EP runs

i 2 Ai / ( bphot (T)) 1 / Qi < 100 Hz

To define a scenario, the users shall have a series of criteria direction of observation roll angle to optimize the projection of the targets onto the CCD criticity of the thermal regulation (level, variability) function of the roll angle criticity of the straylight intensity if any


Spacecraft overviewSpacecraft overview

Spacecraft overview (-Zs sidewall)

Antenne patch GPS -Xs

Antenne patch GPS -Zs

Proteus Corotcase Corotel



Spacecraft overview (+Zs sidewall)

Corotel Corotcase Proteus






Ys+

Xs+Zs+

S

RSF cover

dec < 0

Sidewall in the shade

WINTER - Sun in the back of the satellite



Ys+

Xs+Zs+

SRSF cover dec < 0

Sidewall lightened if roll < 0

WINTER - First days

roll < 0



Ys+

Xs+

Zs+S

RSF cover

dec > 0

Sidewall lightened even if roll = 0increasing flux when roll > 0

WINTER - Last days (round J91)

roll > 0






Equipment bay (COROTCASE) scientific data processing electronics

BCC camera controlBEX extraction units DPU processor

instrument housekeeping electronicsBCV power distribution BS1 analogical payload telemetry BS2 synchronization and thermal regulation

On-board software (COROTLOG) aperture photometry algorithms angle error measurements for AOCS satellite-to-ground link : 900 Mbits/jour



Spacecraft roll domainwinter

Ys+

Zs+

S E

CP and EP n°2

Objective : ± 20°

angle for optimum power budget : = arctan (-tan sin) = 5.25°

Confirmed

for

Beginning of Life


Spacecraft roll domain summer

Ys+

Zs+

CP and EP n°1

E S

Objective : ± 20°

angle for optimum power budget : = arctan (-tan sin) = 5.25°


Confirmed

for

Beginning of Life



System engineering overview System engineering activity currently focused on

instrument modes and in-flight operations all command & control interfaces ground segment architecture use of ground stations system tools for Corotsky light curve corrections level 0/1 products

CCC

PLTMHKTM

Network

CMC

TC

TTCET

TTCET

CDC



Instrument modes

VEILLE

SAFEOFF

VALIDATION ECARTOMETRIE GROSSIERE

VALIDATIONECARTOMETRIE FINE

VALIDATION IMAGE EXOPLANETES

VALIDATION IMAGE ASTERO

VALIDATIONPLAN DE MASQUES

OBSERVATION

Phase de Mise en station

CALIBRATION PERIODIQUE

Modes dédiés aux CALIBRATIONS DEBUT DE VIE



Satellite-to-ground link capacity Station Acquisition Phase Preparation of an observing run

(7 days) VFA + NTL + KRN for many TC/TM operations useful scientific telemetry up to 2.2 Gbits / day



Satellite-to-ground link capacity Observation Phase Observing run (20, 150 days)

VFA + NTL useful scientific telemetry up to 1.4 Gbits / day


Satellite-to-ground link capacity The nominal scientific mission is performed with VFA station

Seismology 12 windows by CCD– 5 star windows, with 2 mask images (over 32 s)

– 5 background windows

– 2 offset windows

Exoplanets 6000 windows by CCD– 4 964 chromatic star windows

– 36 oversampled chromatic star windows

– 949 monochromatic star windows

– 42 oversampled monochromatic windows (including offset)

– 9 imagettes

Total for 2 photometric chains : 958 300 kbits / day




Satellite-to-ground link capacity How the additional telemetry with NTL station can be used ?

More seismology mask images

1 mask image over 32 s --> 45.6 Mbits / day1 mask image over 16 s --> 91.6 Mbits / day1 mask image over 8 s --> 182.4 Mbits / day (mask size = 25 x 25)

More exoplanet imagettes

1 imagette over 32 s --> 6.5 Mbits / day

Examples of scenario Spreadsheet program 5 seismology mask images (over 32 s) + 25 exoplanet imagettes x 2 3 seismology mask images (over 16 s) + 15 exoplanet imagettes x 2 2 seimology mask images (over 8 s) + 20 exoplanet imagettes

+ 2 seismology mask images (over 32 s) + 20 exoplanet imagettes

Total for 2 photometric chains : < 1 400 000 kbits / day


Project statusProject status

Launch of COROT in June 2006 Launch of COROT by SOYUZ/ST from the Guiana Space Center

Choice made by CNES headquartersin July 2002

Maiden flight from Kourou Contract to be signed with Arianespace

before end of 2003, after next ESA Council Civil engineering in Malmanury River

expected before July 2003

If any inacceptable delayon the launch pad work,back-up by ROCKOT from Plesetsk



Documents

1 COROT Science Week, Marseille, 3-6 June 2003 COROT mission Agenda ðSystem progress report §Scenario of observations §Satellite engineering Confirmation