ASPIICS on PROBA-3 Association de Satellites Pour l’Imagerie et l’Interférométrie de la Couronne Solaire San Diego, SPIE August, 26 th 2007 Sébastien Vives,

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

26 August 2007 San Diego - SPIE

2

Proposed 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 coronagraph

Ground-based image obtained during a total solar eclipse

ASPIICS aims at achieving conditions close to total eclipses

ASPIICS Field Of View


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?


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

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t/p

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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


8High resolution imaging…

0

25

50

75

100

125

1 1.25 1.5 1.75 2 2.25

Rsol

Res

olu

tio

n (

arcs

ec) 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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… 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


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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ASPIICS 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


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)


13 Optical Layout

Entrance Pupil

M1

M3

M2

Internal Occulter

O2

O3

Focal Plane

Fabry-PerotBlocking Filters

Polarizer


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


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)


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


17PROBA-3/ASPIICS: programmatic

2006 2007 2008 2009 2010 2011 2012

Phase A

Phase B

Phases C/DOperations

Launch

ITT

Final Decision


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ASPIICS and Formation Flying missions

ASPIICS/PROBA-3 is a needed step toward most demanding future FF missions

.• T

he

cm

arcmin

mm

arcsec

nanometer

sub-arcsec

Step 1

Prisma

Step 3

XeusDarwin

Step 2

Aspiics

2008 20152012 2018


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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ASPIICS on PROBA-3 Association de Satellites Pour l’Imagerie et l’Interférométrie de la Couronne Solaire San Diego, SPIE August, 26 th 2007 Sébastien Vives,

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