Despite the exploration of the solar system by automatic spacecraft, the internal structure of giant planets remains poorly known. As for the Sun, measurement of the velocity field with spatial resolution is achievable, allowing the detection of acoustic modes of low and intermediate degrees. This would permit to investigate the physical conditions inside the giant planets such as the equation of state at high pressure, the transition between the metallic and molecular phase of the hydrogen, and to constraint the scenarios of planetary formation.
In order to achieve this scientific objectives, we propose an observational strategy already used for stellar seismology, with campaign of several weeks of simultaneous observations from three suitable sites in order to achieve the best possible duty cycle. It means to conceive and realise at least three copies of very simple, reliable, stable and efficient spectro-imager.
We have developed a dedicated instrument. The concept of the instrument SYMPA is based on the principle of the Fourier transform spectroscopy. It allows a high resolution with a very compact design and has also imaging capability. A first prototype has been tested on the telescope at Calern observatory, and the observations are being analysed. The first multi-site campaign on Jupiter will take place at the beginning of 2003.
After replacing the project in the context of giant planet seismology, we will present the principle of the instrument and the expected performances, a comparison with the results of the prototype and the planning of observations. Then we will evoke the future of the project, in Antarctica and for stellar seismology.

 
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