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, Philippe Lamy Laboratoire d’Astrophysique de Marseille France: 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.

26 August 2007 San Diego - SPIE 3 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 R sol. 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!

26 August 2007 San Diego - SPIE 4 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

26 August 2007 San Diego - SPIE 5 Scientific 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?

26 August 2007 San Diego - SPIE 6 What 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

26 August 2007 San Diego - SPIE 7 Unique Aspects of ASPIICS  Ambitious science objectives  Imaging the inner corona ( 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 years

26 August 2007 San Diego - SPIE 8 High resolution imaging…

26 August 2007 San Diego - SPIE 9 … With unprecedented spatial resolution  White light imaging ( nm)  from to 3 R sun  at spatial resolution of 2.8 arcsec/px. Pixel limited Diffraction limited

26 August 2007 San Diego - SPIE 10 Methodology: 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, 1.8x10 6 K)  Fe X: nm (coronal holes, 1.0x10 6 K)  He I: nm (cold matter, 1.0x10 5 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)

26 August 2007 San Diego - SPIE 11 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. 16 th 1980) which has allowed to derive: –Intensity, Doppler shift, line broadening and splitting Desai, Chandrasekhar & Angreji, 1981

26 August 2007 San Diego - SPIE 12 Conceptual Layout L1L2 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)

26 August 2007 San Diego - SPIE 13 Optical Layout Entrance Pupil M1 M3 M2 Internal Occulter O2 O3 Focal Plane Fabry-Perot Blocking Filters Polarizer

26 August 2007 San Diego - SPIE 14 Thermo-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

26 August 2007 San Diego - SPIE 15 FF 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)

26 August 2007 San Diego - SPIE 16 Orbit and Launch  Baseline: 24h HEO  800/70000 km  Inclination 63°  Visibility: 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

26 August 2007 San Diego - SPIE 17 PROBA-3/ASPIICS: programmatic Phase A Phase B Phases C/D Operations Launch ITT Final Decision

26 August 2007 San Diego - SPIE 18 ASPIICS and Formation Flying missions  ASPIICS/PROBA-3 is a needed step toward most demanding future FF missions. T h e cm arcmin mm arcsec nanometer sub-arcsec Step 1 Prisma Step 3 Xeus Darwin Step 2 Aspiics

26 August 2007 San Diego - SPIE 19 Conclusion  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 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

26 August 2007 San Diego - SPIE 20 MERCI ! Thank You …

26 August 2007 San Diego - SPIE 21