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Projet Solar orbiter





With its horizon 2000 Plus programme, the European Space Agency has approved the Solar Orbiter mission in order to explore the Sun polar areas in a closer way. The launch of this F3 mission is envisaged for October 2013. It is foreseen to combine in-situ and remote sensing measurements down to a distance of about 40 solar radii, to come out of the ecliptic plan and to co-rotate during a few weeks with the solar surface. With regards to its abilities, the IAS team could be involved in the various types of instruments (imager UV, coronagraph and spectrograph).

Presentation:
Solar Orbiter will be the first satellite to explore the inner areas of our solar system (45 solar radii or 0.22 AU), to follow active areas and to provide very close view of the Sun polar areas from a 35 degrees latitude viewpoint. An electrical propulsion (sub-system common with Bepi – Colombo), combined with a gravitational resonance with Venus will allow to fly on a special orbit.

The payload is composed of optical instruments which allow to measure radial velocities and magnetic fields on the Sun surface (helioseismology), to perform imaging and spectroscopy of the corona & the chromosphere structures in Extreme ultraviolet and X-rays. The in-situ instruments will analyze the solar wind and the magnetic field structures.

The mission is under study at the European Space Agency and the instrument announcement of opportunity is planned for the middle of 2006, with a launch in October 2013.

For more details, you can read
one complete presentation (in PDF format).

Scientific Goals:
With Solar Orbiter we will, for the first time :
  • Determine the properties, dynamics and interactions of plasma, fields and particles in the near-Sun heliosphere,

  • Investigate the links between the solar surface, corona and inner heliosphere,

  • Explore, at all latitudes, the energetics, dynamics and fine-scale structure of the Sun’s magnetized atmosphere,

  • Probe the solar dynamo by observing the Sun’s high latitude field, flows and seismic waves.
Instruments:
The IAS is mainly interested in three remote – sensing instruments : the Extreme Ultraviolet Imager (EUI, the Visible-Light Imager and Magnetograph (VIM) and the EUV Spectrometer (EUS). For the first one, the IAS is preparing, with the EUI consortium, a system study and for the second one, the IAS is interested to participate at the definition of scientific objectives.

The principal scientific goal of the EUV Imager is to provide EUV images with at least a factor 2 higher spatial resolution than currently available in order to reveal the fine-scale structure of coronal features, to provide full-disc EUV images of the Sun in order to reveal the global structure and irradiance of inaccessible regions such as the "far side" of the Sun and the polar regions and to study the connection between in-situ and remote-sensing observations. The instrument consists of :
  • A High Resolution Imager (HRI) based on three telescopes operating in different wavelength bands in order to observe both the quiet Sun network regions and the coronal loops. The present wavelength choices for the reference design were 13.3, 17.4 and 30.4 nm covering temperatures from 5.10e4 K to 1,6.10e7 K,
  • A Full Sun Imager (FSI) based on a single telescope operating in the wavelength range from 13.3 to 30.4 nm in order to provide a global insight into changes in the solar atmosphere and in addition to provide context information for other instruments.

The principal scientific goal of the VIM is to measure the magnetic and velocity fields in the photosphere. The instrument consists of :
  • A 25 cm diameter High Resolution Telescope (HRT) ,
  • A 5 cm diameter Full Disk Telescope (FDT) ,
  • Filtergraph Optics (FO).
The two telescopes which deliver an image of the Sun at a common focal plane are to be proposed by the MPS.


The purpose of the EUS is to determine the plasma density, temperature, element/ion abundances, flow speeds and the structure of the solar atmosphere using spectroscopic observations of emission lines in the UV/EUV. The instrument consist of :
  • A single parabolid primary mirror,
  • A spestrometer which utilises a variable line spaced (VLS) grating in a normal incidence configuration.