Réunion de présentation des besoins 10 Nov. 2006 1 Joël MICHAUD French expertise in SiC for large telescopes

Réunion de présentation des besoins 10 Nov. 2006 1Joël MICHAUD

French expertise in SiC for large telescopes


SiC technology

• Technology promoted and developped by French industry for more

than 10 years for space applications.

• Technology renowned in the whole world.

• All developments in europe including a large telescope are currently

manufactured with SiC technology.

– Herschel telescope, diameter 3.5 m, mass 300 kg

– Aladin lidar (wind), diameter 1.5 m, mass 72 kg

– Primary GAIA mirror, off axis aspherical, 1.45 x 0.55 m, 36 kg


Key advantages of SiC technology

• Very high weight reduction thanks to an exceptional stiffness of the material (~5 times

higher than aluminium or Zerodur)

• Optical material, very good specularity of SiC CVD (Chemical Vapor Deposition)

• Homogeneous material with a cristalline structure, low CTE (Coefficient of Thermal

Expansion) and high thermal conductivity, usable on a large thermal range (0K –

1800K)

• High mechanical stiffness permitting to manufacture the structure in SiC

• The material is insensitive to radiation and humidity

• Existing industrial facilities and mature technology to manufacture large parts.

Assembling technology controled

high eigen frequencies possible, robust thermal control, stability, robustness of

manufacturing and modelisation, all SiC telescope performance preserved at cryogenic

temperatures


Achievements examples, all SiC design

ROCSAT2 Telescope, launched in 2004600 mm diameterTelescope mass 70 kg

Osiris telescope (Rosetta mission launched in 2004)150 mm diameterOperational temperature -100/+70°C

Herschel telescope (ESA program)3.5 m diameter, 80 µm to 670 µm, no CVD)Cryogenic temperature (~80 K)Primary mirror mass 210 kg (22 kg/m²)


Achievements examples

AEOLUS/ALADIN (ESA program, Wind Lidar 360 nm)Telescope delivery 2005, launch 20081.5 m diameter, no CVDPrimary mirror mass 50 kg (28 kg/m²)

GAIA (ESA program)M1 mirror delivery 20051.45 x 0.55 mirror off axis CVDPrimary mirror mass 36 kg


Proposal for aSNAP PASO Study


Plannification of PASO Studies

• PASO Studies are decided on an annual basis

• A preselection of studies have been proposed, including SNAP Study

• Resources for preselected studies are being evaluated (human CNES resources and/or cost)

• A final choice will be done before end of year considering availability of CNES technical services and financial allocations

Next slides describe a proposition for this SNAP study


Purpose of the SNAP PASO Study

• Assess a possible french participation to SNAP mission

– Spectrometer supply

– Optical Telescope Assembly (OTA) supply

– Other supply

– ROM cost

• Better understand Weak Lensing (WL) problematic through an

iteration between scientific requirements and induced outcomes on

second level requirements and telescope design

– Work has still to be done to clearly establish relations between Weak Lensing

requirements and design features at all levels (mission, system, spacecraft,

instrument, optics, etc …), as it is not straighforward

– To make a good proposal means to clearly understand the requirements.


Expectations

• A possible proposal for a french participation to SNAP mission

– Technical outline

– Technical solution

– ROM cost

• A french expertise on Weak Lensing problematic

• An enhance french scientific contribution to SNAP team

• A PASO report including

– Proposal for enhanced Weak Lensing requirements

– A scenario for a telescope design consistent with Weal Lensing and

Supernovae requirements

– PSF models to allow iterations between technicians and scientists

– A detailed cost estimate for the telescope supply.

• An expertise for the spectrometer development in LAM


Study schedule

• Phase 0.1: Requirements and design options, required interface SNAP

data

– Study kick off (French scientific group, CNES/partners)

– Progress meetings

– Phase 0.1 Key Point (French scientific group, CNES/partners, SNAP team

invited)

• Phase 0.2: Telescope design options studies, PSF modelisation, ROM

cost

– Progress meetings

– Phase 0.2 and final Key Point (French scientific group, CNES/partners, SNAP

team invited)


Phase 0.1

• Tasks– Analyse current SN and WL requirements

– Analyse SNAP current design

– Analyse current telescope requirements

– Confirm or complete WL requirements (with scientists)

– Update telescope requirements if necessary

– Define or complete SNAP/OTA interface (ICD)

– Define relations between WL requirements and design options

– Propose telescope design options

– Elaborate scenarios for WL requirements versus design options

– Define the outline of a PSF modelisation• List effects to be taken into account• Define PSF modelisation depth• Define the SNAP/OTA interface data needed for the PSF modelisation

– Define the PSF calibration process outline


Phase 0.1

• Outputs– Options for the telescope design

– PSF modelisation method

– Calibration process outline

– Exchange data format between scientists and technical team (for PSF for instance)

– Preliminary SNAP/OTA Interface (ICD)

– Needed data from SNAP US team (SNAP/OTA interface data), specificaly for PSF modelisation

• General mission data (scanning laws, orbit simplified model …)• Spacecraft simplified general thermal model• Focal plane detailed thermal/thermoelastic model• Detectors characteristics (charge diffusion, ….)• Attitude control characteristics and features (jitter amplitudes, frequencies and

orientation, …)• Etc…

– Phase 0.1 Key Point presentation


Phase 0.2

• Tasks

– Study telescope design options

– Elaborate a PSF modelisation including OTA effects and external effects

– Analyse the sensitivity of Weak Lensing performances to telescope design

features and PSF shape (iterative process between engineers and scientists)

– Define the PSF calibration process

– Confirm WL requirements at all levels

– Make recommandations on the design (confirmations or alternatives)

• At system level (scanning, WL/SN observation sequences, etc ….)

• At spacecraft level (thermal, attitude control, instrument,…)

• At instrument level (Focal Plane/Optics interface, …)

• At telescope and spectrometer level (proposed design options)

– Define needed Research and Technology anticipating program

– Estimate the cost for a french participation to SNAP


Phase 0.2

• Outputs– PSF models

– A Weak Lensing sensitivity analysis (from french scientific group)

– A PASO report including

• A proposal for a telescope and spectrometer design for SNAP, with the

justification of chosen technical options

• The definition of a calibration process and the associated requirements

• Telescope and spectrometer performances budgets

• Risk analysis

• Costs

• TRL level for telescope and spectrometer items and needed Research and

Technology actions

– A phase 0.2 Key Point presentation


Organisation

French scientific group

CNES team (Statement of work

study follow upInterface)

Technical team

SNAP team

•Statement of work/Follow up•Key point organisation•SNAP/OTA interface data supply

•Study Proposal•Needed SNAP/OTA inteface data•Progress meetings•Final technical report

•PSF models•Telescope design definition•Spectrometer expertise

•Scientific requirements•Calibration process design (WL)•WL sensitivity analysis

•Scientific requirements•Calibration process design (WL)

•Final PASO report

•Scientific requirements

•SNAP/OTA interface data supply

•SNAP/OTA interface data

CNES Program and strategy department

(study client)

•Final PASO report•SNAP study request

•Proposal for a french participation to SNAP


Tentative Schedule

Feb AugJulJunMayAprMar Sept Oct

Phase 0.1

Phase 0.2

CENA Ph01 KP

PASO Report

Ph02 KP

KO Ph0.1

2007

CENA : Commission d’Engagement des Nouvelles AffairesKO : Kick-OffKP : Key Point

Dec JanNov

Instruction/Statement of work

Présentation

2006


About this proposal

• Activities, organisation, schedule in these slides are only

suggestions for a statement of work preparation

• They are subject to changes due to– SNAP team comments

– LAM and French scientific group comments

– PASO activities and funding

– Availability of CNES technical teams

Documents

Réunion de présentation des besoins 10 Nov. 2006 1 Joël MICHAUD French expertise in SiC for large telescopes