Advanced Studies and Technology Preparation Division 1 SPICA Mission profile M class presentation...

Advanced Studies and Technology Preparation Division

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SPICA Mission profile

M class presentation

Paris, 1 December 2009


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Overview of SPICA mission

• SPICA is a JAXA led mission scheduled for launch by 2018 (Phase A).• Medium and far IR observatory (5 – 210 um), with sky background limited

sensitivity via a cryogenically cooled telescope (3.5 m diameter, T < 6K).• Launcher vehicle is JAXA’s HII-B. Large halo orbit at SE-L2 (P ~ 180 days).• Nominal mission lifetime: 3 yr (5 yr goal).


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Overview of SPICA mission

• SPICA is a JAXA led mission scheduled for launch by 2018 (Phase A).• Medium and far IR observatory (5 – 210 um), with sky background limited

sensitivity via a cryogenically cooled telescope (3.5 m diameter, T < 6K).• Launcher vehicle is JAXA’s HII-B. Large halo orbit at SE-L2 (P ~ 180 days).• Nominal mission lifetime: 3 yr (5 yr goal).

• Cryogenic model payload (cryogens free): - Cryogenically cooled telescope assembly.- MIRACLE (MIR camera & spectro-photometer).- SAFARI (FIR imaging spectrometer).- MIRHES (MIR High Resolution Spectrometer)- MIRMES (MIR medium resolution spectrometer).- SCI (MIR coronagraph).- FPC (Focal Plane Camera dedicated to guidance).- BLISS (FIR and sub-mm spectrometer – optional).


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The SPICA spacecraft

Configuration: Cryogenic PLM supported by an octagonal SVM via truss structure. ~ 4.4 m diameter, 7.5 m high.

Mass & power: Total mass ~ 4 ton; total peak power ~ 2.4kW (EOL).

Attitude Control: 3-axis stabilised. RW’s. Focal Plane Camera (FPC) in AOCS loop (to meet RPE < 7.5 mas/200s).

Thermal Control Passive cooling via coaxial Sun and thermal shields, System: (reaching ~11K). Active cooling via 2-stage Stirling

and JT units (4.5 and 1.7 K stage).

Propulsion: Monopropellant (blow down), propellant: 220 kg.

Data Handling: Centralised DPU, MM > 48 Gbyte. Science data: 24h * 4 Mb/s = 350 Gbit/day.

TT&C: X-Band (HGA, MGA for down-link), S-band (2 LGAfor up and down-link).

Ground segment: Usuda (JAXA), Cebreros or DS3 (4 hr/day).


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Inner Shield

Middle Shield

Outer Shield


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European contribution to SPICA1. SPICA Telescope Assembly:

ESA (Industrial assessment study, TAS-France and EADS Astrium France)- M1, M2 and associated internal baffles. - M2 supporting structure, M2 mechanism and associated drive electronics.- Telescope Optical Bench.- Thermal HW (S/MLI, T sensors, heaters).

2. SAFARI instrument: SPICA FIR Imaging Spectrometer (assessment study carried out by the instrument consortium). ESA acting as official interface to JAXA.

3. GND segment contribution: provision of a ground station for 4hr/day (subject of an internal ESA assessment).

4. European Science Centre: supporting the European scientists in accessing the SPICA observatory (subject of an internal ESA assessment).


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SPICA Telescope Assembly (STA)


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SPICA Telescope Assembly (STA)


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Telescope assessment studyMain requirements:• Diffraction limited performance at = 5 um. • Optical surfaces at T< 6K.• Total mass (including design margins) < 700 kg.• M2 structure based on 4-leg design (Coronagr. requirements).• Interface to SVM via Telescope Optical Bench.

ASF

TAS


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Telescope assessment studyMain requirements:• Diffraction limited performance at = 5 um. • Optical surfaces at T< 6K.• Total mass (including design margins) < 700 kg.• M2 structure based on 4-leg design (COR requirements).• Interface to SVM via Telescope Optical Bench.

Baseline design:• Ritchey-Chretien design (confirmed by both contractors). • All ceramic design (mirrors and support structure) selected by

Astrium (SiC100) & TAS (HB-Cesic).• Dedicated Instrument Optical Bench confirmed.• Focus and tip/tilt mechanism (at M2).• Detailed thermal and mechanical analysis performed.• Optical surfaces at T < 6K; heat load ~ 20 mW at 4.5K.• Thermo-elastic analysis shows compliance with WFE req.t.• Overall feasibility confirmed by assessment study.• STM + PFM. PFM delivery to JAXA by Q1-Q2/17.

ASF

TAS


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European contribution: SAFARIMain requirements:• Imaging and spectroscopy (continuous wavelength coverage

in the range 34 – 210 um).• Photometric camera mode with R ~ 2 to 5.• Spectroscopic mode with R = 2000 at 100 um.• FOV = 2 x 2 arcmin2. Line sensitivity ~3E-19 W/m2 (48 um).• Mass of cold assembly < 50 kg. Warm electronics < 30 kg.• Flight Model delivery to JAXA required by end 2015.


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European contribution: SAFARIMain requirements:• Imaging and spectroscopy (continuous wavelength coverage

in the range 34 – 210 um).• Photometric camera mode with R ~ 2 to 5.• Spectroscopic mode with R = 2000 at 100 um.• FOV = 2 x 2 arcmin2. Line sensitivity ~3E-19 W/m2 (48 um).• Mass of cold assembly < 50 kg. Warm electronics < 30 kg.• Flight Model delivery to JAXA required by end 2015.

Baseline design:• Imaging Fourier Transform Spectrometer (34 - 210 um).• 3x Focal Plane Arrays – Modified Mach-Zehnder interferom.• ~ 6000 px. Selection of detector technology impacts design

(TES, KID, Si bolometers, Photo-cond. planned by mid 2010).• Phase A study conducted assuming adoption of TES (design

stressing case approach).• Additional internal cooler required by TES, KID and Si-

Bolometer (Sorption Cooler + ADR ~ 100 mK).

• Key role within SPICA payload complement (FIR coverage).• Herschel class instrument (c.f. SPIRE, PACS).


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SPICA ground segment

Mission Operations Centre:• Located in Japan linked to JAXA’s SOC.• Primary station Usuda (64m), additional

ESOC station (Cebreros / DS3).• JAXA SOC interfaced to ESA’s SOC.

European SPICA Science Centre:• ESA SPICA Science Centre (ESSC) located at ESAC.• SAFARI Instrument Control Centre, distributed in several European

countries, contact via PI (SRON).• ESSC to act as interface for the European community to the SPICA

observatory and interface between SAFARI ICC and JAXA’s SOC/MOC,


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ESA review: risk items

STA:• Further consolidation of interface requirements.• Focusing mechanism development (dedicated TDA planned).• Schedule driven by M1 polishing (dedicated TDA planned).


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ESA review: risk items

STA:• Further consolidation of interface requirements.• Focusing mechanism development (dedicated TDA planned).• Schedule driven by M1 polishing (dedicated TDA planned).

SAFARI:• Further consolidation of interface requirements.• Early selection of focal plane detector technology required.• FTS scanning mechanism, internal cooler and FEE development (TDAs).• Revision of development plan, in view of meeting PFM delivery date.


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Conclusions of assessment activities

The European industry and scientific community are very well placed to contribute effectively to the SPICA mission:

• Large heritage from Herschel programme allows to exploit expertise and to minimise the development risk.

• The Telescope Assembly is feasible and can be developed by the European industry with an acceptable level of risk.

• The SAFARI instrument can rely on significant heritage and expertise with the consortium (e.g. SPIRE, PACS).

• The provision of MOC and SOC services by ESA does not present any critical issues.


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Conclusions of assessment activities

The European industry and scientific community are very well placed to contribute effectively to the SPICA mission:

• Large heritage from Herschel programme allows to exploit expertise and to minimise the development risk.

• The Telescope Assembly is feasible and can be developed by the European industry with an acceptable level of risk.

• The SAFARI instrument can rely on significant heritage and expertise with the consortium (e.g. SPIRE, PACS).

• The provision of MOC and SOC services by ESA does not present any critical issues.

The European contribution to SPICA is a real ‘mission of opportunity’, with the potential of a large scientific return

at a fraction of an M class mission cost.


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END


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Main telescope requirements

Main SPICA Telescope Assembly (STA) requirements applicable to the study:

Optical design: Ritchey-Chretien, axi-symmetric, EFL=20m, M1 dia = 3.5 m

Operating temperature: Nominal < 6K, operating range 4-10 K

Wavelength range: 5 to 210 um (goal 3.5 to 210 um)

Collecting aperture: 3.5 m diameter (maximum allowed by HII-B fairing)

Total obscuration: < 12.5 % on axis (goal < 10%)

Total transmission: > 90% at 5 um, > 95% at 15 um, > 99% at 110 um

Image quality: Diffraction limited at 5 um over a FOV of 5 arcmin (WFE < 350 nm RMS, over 5’ radius)

Field Of View: > 12 arcmin (unvignetted)

Launch environment: JAXA launcher HII-B, cool down after launch (passive + active cooling).

STA mass allocation: < 700 kg (including margins, excluding mass of IOB)

Stray-light rejection: Total background from out-of-field stray sources (artificial and natural) < 20% of in-field background (zodiacal light and self emission from telescope).

Lifetime: > 5yr in orbit (and > 5 yr on ground)

Functional requirements: -M2 refocusing at nominal operating temperature.-In-flight decontamination capability.

Advanced Studies and Technology Preparation Division 1 SPICA Mission profile M class presentation...

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