Proposal coordinator:

Luc Damé, Service d'Aéronomie du CNRS, IPSL, BP 3, F-91371 Verrières-le-Buisson Cedex, FRANCE,

Tel.: (+33) 1 64 47 43 28

Fax: (+33) 1 69 20 29 99

e-mail: luc.dame@aerov.jussieu.fr

Proposal team members:

– J.L. Bertaux, Service d'Aéronomie du CNRS, Verrières-le-Buisson, France
– A. Cacciani, University of Rome, Italy
– F. Clette, Observatoire Royal de Belgique, Bruxelles, Belgium
– R. Cowsik, Indian Institute of Astrophysics, Bangalore, India
– P. Cugnon, Observatoire Royal de Belgique, Bruxelles, Belgium
– S. Dewitte, Institut Royal Météorologique de Belgique, Bruxelles, Belgium
– C. Fröhlich, Physikalisch-Metorologisches Observatorium, Davos, Switzerland
– M. Hersé, Service d'Aéronomie du CNRS, Verrières-le-Buisson, France
– A. Joukoff, Institut Royal Météorologique de Belgique, Bruxelles, Belgium
– R. Kariyappa, Indian Institute of Astrophysics, Bangalore, India
– A. Preumont, Université Libre de Belgique, Bruxelles, Belgium
– E. Quémerais, Service d'Aéronomie du CNRS, Verrières-le-Buisson, France
– W. Schmutz, Physikalisch-Metorologisches Observatorium, Davos, Switzerland
– G. Thuillier, Service d'Aéronomie du CNRS, Verrières-le-Buisson, France
– T. Toutain, Département Cassini, Observatoire de Nice, France

Mission Objectives

The global understanding of the Solar machine and its influence on Earth is at the center of the three major thematics addressed by SPI. They are complementary: the internal structure of the Sun explaining the surface activity, and magnetic structuring explaining in turn the variations and influence of the Sun on Earth. The major goals of the SPI mission are:

• to reveal and understand the detailed structure and evolution of the solar atmosphere. SPI high resolution imaging and spectros-copy will trace the Sun’s magnetic field structure and evolution from the photosphere to the corona. SPI will reveal the links between the layers of the Sun’s atmosphere. It will track the complete evolution of magnetic processes from the smallest scales to the largest, address magnetic emergence and reconnection, the development and regression of active regions, the development and nature of transient events in the atmosphere, the onset and fine structure of flares from the smallest (nanoflares) to the larg-est (white light chromospheric flares), and the propagation of magnetic activity through the different regimes of the solar atmos-phere.
• to reveal the internal structure of the Sun, the transfer from the radiative to the convection zone, the links between internal flows and the magnetic cycle. Magnetic activity and its variations are the consequences of the internal regimes of convection. g modes and long-period p modes are the only one capable to penetrate deeply enough to constrain the solar internal parameters. These modes are best observed at the limb where their amplitude is 4 to 5 times greater than for full-disc measurements. Moreover, second generation observation of local oscillations guarantees the correct understanding of the transition from inside to outside the Sun, from sub to surface flows and manifestations.
• to measure and understand the profound influence of the Sun on the Earth and the consequences for our life through the predic-tions of long-term (10–200 years) climatic changes. SPI carries the new generation of Solar diameter, Solar constant, strato-spheric UV and IR flux inputs and Lyman alpha monitors. They are necessary to measure and follow in great details the Solar inputs re-ceived on Earth and their variations with an unprecedented absolute precision (for instance, the Solar diameter measurement will have a noise level of 1 milli-arcsec which, in turns, means a milli-degree in global cooling or warming).

Mission and Spacecraft Summary

Scientific Objectives	Solar imaging, spectro-imaging, helioseismology and Solar activity: · Spectroscopy and imaging at very high spatial and temporal resolution · Helioseismology, resolved and global oscillations, g-modes (diameter oscillations) · Solar variability, influence of the Sun on the climate, Space weather (Lyman Alpha imaging)
Payload	8 Instruments and adaptation totaling 430 kg and consuming 350 W power (with thermal control included) Solar instrumentation - Imagers and spectrometers: – SOLARNET Ø1 m interferometer with its UV spectro-imager system (UVIS) – EUV Imager and Spectrometer – X-Ray/EUV Imager Oscillations and Solar Variability Package (on Sage III type Hexapod) – OVIM-MOF (resolved velocity oscillations and magnetographs) – NG-PICARD (limb oscillations, g-modes, and absolute diameter measure) – NG-DIARAD/VIRGO (solar constant, global and resolved intensity oscillations – Ultraviolet and Visible Light Coronograph 1.1–2.6 Solar radius Space weather – NG-SWAN Full sky Lyman Alpha imager
Launcher	Dedicated launch with Rockot (launcher payload 830 kg). Nominal launch from Plesetsk (62.7°) well situated (high latitude) for an injection on a polar orbit. Non-eclipsing 6:00-18:00 polar orbit 1000 km height.
Spacecraft	· Design lifetime = 2 y, consumables sized for 6 y (extended mission) · Total mass = 830kg · Main S/C bus (with payload): 300 cm x Ø170 cm. · 3-axis stabilised · Pointing stability better than 1 arcsec/15 seconds and 5 arcsec/15min · Deployable Solar arrays (no rotation) of 800 W (4m2) · X-band LGAs, omni coverage, for TM · 2 S-band antennae for TC

SPI Mission Proposal in pdf form:

SPI Proposal, ESA F2/F3, January 31, 2000

References (omitted in the first version of the proposal)

Complements and references: