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cw4 boisnard

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Published on January 17, 2008

Author: Vittoria

Source: authorstream.com

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COROT mission:  COROT 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 report:  Instrument progress report COROTCASE COROTEL COROTLOG COROTCAM PROTEUS System progress report:  System progress report Satellite engineering overview Many activities Spacecraft mathematical model for 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 COROT mission:  COROT mission 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 COROT mission:  COROT mission Orientation of the satellite - flight domain Sun COROT mission:  COROT mission The sky observed by COROT COROT mission:  COROT mission Satellite design / axes Equipment bay Upper compartment with sensitive equipment Fine thermal regulation subsystem COROT mission:  COROT mission 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 incidence no 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 COROT mission:  COROT mission New mission schedule Thermal constraints shrunk to payload constraints the Ys+ satellite wall (focal unit radiator) must be in the shade as 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 beginning or 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 COROT mission:  COROT mission 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 COROT mission:  COROT mission Eclipses (over the year) max : 0.34 Torb COROT mission:  COROT mission Previous schedule “Peace and Love” Line of nodes Summer Winter Autumn Solar declination up to +23° Ys+ Solar declination down to –23° Central Program 2 Exploratory Programs 1 & 2 180° rotation on Zs 180° rotation on Xs 180° rotation on Xs 180° rotation on Zs Satellite axes in a fixed orbital reference frame ROF XJ2000 YJ2000 XOF ZOF Equatorial plane 12.5° Earth orbit Central Program 1 Line of Equinoxes Spring S Anticenter (6h50) Center (18h50) COROT mission:  COROT mission Updated schedule “Piece of cake” Line of nodes Summer Winter Autumn Solar declination up to +23° Solar declination down to –23° Central Program 2 Exploratory Programs 1 & 2 180° rotation on Zs 180° rotation on Zs Satellite axes in a fixed orbital reference frame ROF XJ2000 YJ2000 XOF ZOF Equatorial plane 12.5° Earth orbit Central Program 1 Line of Equinoxes Spring S 1b 1a 2b 2a Center (18h50) Anticenter (6h50) COROT mission:  COROT mission Line of nodes Summer Autumn Solar declination up to +23° EP 1 180° rotation on Zs 180° rotation on Zs Satellite axes in a fixed orbital reference frame ROF XJ2000 YJ2000 Equatorial plane 12.5° Earth orbit CP 1 Line of Equinoxes Spring 1b 1a 18h50 Favorable direction in the observation cone RA + S COROT mission:  COROT mission Line of nodes Winter Autumn Solar declination down to –23° CP 2 EP 2 180° rotation on Zs 180° rotation on Zs Satellite axes in a fixed orbital reference frame ROF XJ2000 YJ2000 Equatorial plane 12.5° Earth orbit Line of Equinoxes Spring Xs+ Zs- Ys+ 2b 2a 6h50 Favorable direction in the observation cone RA + S COROT mission:  COROT mission Straylight maximum level (on the orbit) as a function of time case of winter COROT mission:  COROT mission 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 periodic perturbations (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 overview:  Spacecraft overview Spacecraft overview (-Zs sidewall) Antenne patch GPS -Xs Antenne patch GPS -Zs Proteus Corotcase Corotel Spacecraft overview:  Spacecraft overview Spacecraft overview (+Zs sidewall) Corotel Corotcase Proteus Spacecraft overview:  Spacecraft overview Spacecraft overview (+Zs sidewall) Spacecraft overview:  Spacecraft overview Ys+ Xs+ Zs+ S RSF cover dec < 0 Sidewall in the shade WINTER - Sun in the back of the satellite Spacecraft overview:  Spacecraft overview Ys+ Xs+ Zs+ RSF cover dec < 0 Sidewall lightened if roll < 0 WINTER - First days roll < 0 Spacecraft overview:  Spacecraft overview Ys+ Xs+ Zs+ RSF cover dec > 0 Sidewall lightened even if roll = 0 increasing flux when roll > 0 WINTER - Last days (round J91) roll > 0 Spacecraft overview:  Spacecraft overview Spacecraft overview (+Zs sidewall) Spacecraft overview:  Spacecraft overview Equipment bay (COROTCASE) scientific data processing electronics BCC camera control BEX extraction units DPU processor instrument housekeeping electronics BCV 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 System progress report:  System progress report Spacecraft roll domain winter CP and EP n°2 Objective : ± 20° angle for optimum power budget :  = arctan (-tan sin) = 5.25° Confirmed for Beginning of Life System progress report:  Spacecraft roll domain summer CP and EP n°1 Objective : ± 20° angle for optimum power budget :  = arctan (-tan sin) = 5.25° System progress report Confirmed for Beginning of Life System progress report:  System progress report 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 System progress report:  System progress report Instrument modes System progress report:  System progress report 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 System progress report:  System progress report Satellite-to-ground link capacity Observation Phase Observing run (20, 150 days) VFA + NTL useful scientific telemetry up to 1.4 Gbits / day System progress report:  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 System progress report System progress report:  System progress report 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 / day 1 mask image over 16 s --> 91.6 Mbits / day 1 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 status:  Project status Launch of COROT in June 2006 Launch of COROT by SOYUZ/ST from the Guiana Space Center Choice made by CNES headquarters in 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 delay on the launch pad work, back-up by ROCKOT from Plesetsk System progress report:  System progress report

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