San Diego, SPIE August, 26 th 2007
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ASPIICSASPIICS on PROBA-3 on PROBA-3Association de Satellites Pour Association de Satellites Pour
l’Imagerie et l’Interférométrie de l’Imagerie et l’Interférométrie de la Couronne Solairela Couronne Solaire
San Diego, SPIEAugust, 26th 2007
Sébastien Vives, Philippe LamyLaboratoire d’Astrophysique de MarseilleFrance: P. Levacher (LAM), M. Marcellin (LAM), S. Koutchmy (IAP), J. Arnaud (LUAN), E. Quemerais (SA), L. Damé (SA), R. Lallement (SA), J. C. Vial (IAS) UK: R. Harrisson (RAL), N.R. Waltham (RAL)Belgium: P. Rochus (CSL), J. M. Defise (CSL), D. Berghmans (ORB), J. F. Hochedez (ORB) Spain: J. Pacheco (ASRG/UAH), J. Blanco (ASRG/UAH) Portugal: J. M. Rebordao (INETI/LAER), D. Maia (INETI/LAER) Switzerland: W. Schmutz (PMOD/WRC), A. Benz (PMOD/WRC) Italy: G. Naletto
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2Proposed scientific Payload for PROBA-3
The proposed scientific payload for the PROBA-3 mission is composed of:
ASPIICS: Association de Satellite Pour l’Imagerie et l’Interferometrie de la Couronne Solaire
• a giant solar coronagraph to observe the middle corona with high spatial resolution and diagnostic (spectral) capability.
ARaSS: New generation Absolute Radiometer and Sun Sensor
• ARaSS will contribute to the long-term measurement of the solar constant, and could possibly be operated beyond the nominal lifetime of the FF mission at very little cost.
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Current observational status of the inner corona
After 40 years of space coronagraphy the lower corona (<2.5Rsol) remains practically unobserved
STEREO/COR-1 is also affected by large amounts of stray light and it needs an elaborated image reduction process to reveal bright structures from 1.4 Rsol.
SOHO/LASCO-C2
R > 2.5 Rsol
SOHO/LASCO-C1
High level of straylight
and operated at solar minimum only
Ground-based coronagraph:
Low spatial resolution and atmospheric noise
Total solar Eclipses:
Ideal but very rare and only a snapshot!
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Ground-based coronagraphSOHO/LASCO-C1 coronagraph
ASPIICS objectives
SOHO/LASCO-C2 coronagraphGround-based image obtained during a total solar eclipse
ASPIICS aims at achieving conditions close to total eclipses
ASPIICS Field Of View
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5Scientific objectives
ASPIICS will offer a unique perspective to study processes occuring above 1.02 Rsun in both W-L and monochromatic ionic emissions.
ASPIICS will allow characterizing the main magnetic, dynamical and thermo-dynamical processes in the inner corona
ASPIICS will adress the following questions: How is the corona heated? What is the role of waves? How are the different components of the solar wind, slow and
fast, accelerated? To what degree do coronal inhomogeneities affect the heating
and acceleration processes? How are CMEs accelerated? What is the nature of the interaction between the CME plasma
and the magnetic field that drives the eruption? What is the configuration of the magnetic field in the corona?
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6What is ASPIICS ?
2 S/C separated by 150 m realize a giant coronagraph and will achieve conditions close to a total solar eclipse
Performances are driven by the distance between the external occulter and the entrance pupil
ww
w.e
sa.in
t/pro
ba
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7Unique Aspects of ASPIICS
Ambitious science objectives Imaging the inner corona (1.075 - 3 Rsol) at high spatial
resolution (<3arcsec/px) Diagnostics of emission lines (velocity, turbulence, waves) Topology of the coronal magnetic field
Operating in the visible 3D spectroscopy of coronal emission lines Simplicity
Optimum conditions Drastic reduction of instrumental stray light
NO competitor in the coming 10-15 years
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8High resolution imaging…
0
25
50
75
100
125
1 1.25 1.5 1.75 2 2.25
Rsol
Reso
lutio
n (a
rcse
c) Optical resolution of LASCO-C2 [occulter-pupil ~0.8 m]
Optical resolution of a rocket flight (launched in mi-2007)
[occulter-pupil ~2.5 m]
Optical resolution of ASPIICS (ISD = 150m)
Optical resolution of ALASCO [occulter-pupil ~13 m]
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9… With unprecedented spatial resolution
White light imaging (540-630nm) from 1.075 to 3 Rsun at spatial resolution of 2.8 arcsec/px.
Pixel limited
Diffraction limited
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10Methodology: 3D-spectroscopy
Superimpose a system of fringes on the coronal image
Get all the spectral information in one image Fe XIV: 5303 nm (coronal matter, 1.8x106 K) Fe X: 637.4 nm (coronal holes, 1.0x106 K) He I: 587.6 nm (cold matter, 1.0x105 K)
Tilt the F-P to displace the fringe pattern and improve the spatial coverage
Scientific quantities: Ion densities (from intensities) Temperatures (line broadening and
comparison with W-L) Velocities (Doppler shifts) Turbulence (non thermal velocities)
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11ASPIICS with a Fabry-Perot (F-P)
This solution has already been validated by several eclipse experiments on ground
• Coronal interferogram on FeXIV emission line obtained during a total eclipse (Feb. 16th 1980) which has allowed to derive:
– Intensity, Doppler shift, line broadening and splitting
Desai, Chandrasekhar & Angreji, 1981
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12Conceptual Layout
L1 L2 L3
F-P
Filter Wheel
Detector
Internal occulter Polarizer
Cover (door)
Shutter
Coronagraphic function: The L1-objective re-images the occulting disk into the internal occulter
to minimize straylight. Spectro-polarimetric function:
The Fabry-Perot is located at the “Lyot stop” (pupil image) in a collimated beam after L2.
The polarizer is located in a collimated beam after L2. Imaging function:
The L3-objective re-images the FOV onto a 2048x2048 CCD (15µm)
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13 Optical Layout
Entrance Pupil
M1
M3
M2
Internal Occulter
O2O3
Focal Plane
Fabry-PerotBlocking Filters
Polarizer
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14Thermo-Mechanical Concept
The Coronagraph Optical Box (COB) appears as a parallelepiped in composite panels
The structure is decoupled from the S/C, mechanically and thermally, thanks to titanium bipods.
The thermal concept is based on both passive (MLI blanket) and active control (thermal lines).
The structure supports the CCD detector radiator by insulating spacers.
CEB
CCB
CCD radiator
M1
M3
FPA
M2
CEB
CCB
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15FF Specifications
Inter-Satellite Distance (ISD) ~ 150 m (±2 m variation over the year)
Absolute Displacement Error (ADE) Lateral positioning:
• ± 3.4mm (3) with 20 arcsec APE• Can be relaxed to ± 6.0mm (3) at the expense of
the APE (8 arcsec) Longitudinal positioning: ±740mm (3)Inter-Satellite Distance (ISD) Absolute Displacement
Error (ADE)
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16Orbit and Launch
Baseline: 24h HEO 800/70000 km Inclination 63° Visibility: 15-20 hrs/day Eclipses (typical): from 0 to 3.9
hrs (180 days without eclipses per year)
Launch 515 kg on a dedicated launch on
VEGA/Verta launch (415 kg current)
Create/Delete FF
Launch Configuration
Coronagraph S/C
Occulter S/C
Lisa Path Finder Module
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17PROBA-3/ASPIICS: programmatic
2006 2007 2008 2009 2010 2011 2012
Phase APhase B
Phases C/DOperations
Launch
ITT
Final Decision
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18ASPIICS and Formation Flying missions
ASPIICS/PROBA-3 is a needed step toward most demanding future FF missions
.• Th
e
cmarcmin
mmarcsec
nanometersub-arcsec
Step 1
Prisma
Step 3
XeusDarwin
Step 2
Aspiics
2008 20152012 2018
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19Conclusion
ASPIICS will address still unanswered science questions that the failed SOHO/LASCO-C1 coronagraph was supposed to investigate. Thanks to the following major improvements: Straylight level: Externally occultation vs internally occultation Spectral selection: Etalon Fabry-Perot vs Tunable Strategy: Spatial vs spectral sampling
ASPIICS has no competitor in the coming 10-15 years
ASPIICS will give tremendous visibility to ESA's formation flying program thanks to spectacular results (movies of "explosions" are perfect for outreach)
ASPIICS will operate in synergy with contemplated disk imagers and wide field coronagraphs (SDO, SMESE, INTER-HELIOS, PROBA-2)
ASPIICS will help to prepare future formation flying missions
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MERCI !Thank You …
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