for his profound and wide-ranging contributions to planetary thermal radiation, the composition and aeronomy of the atmospheres of giant planets, and planetary oscillations

Daniel Gautier started his research career when studying planetary thermal radiation by inverting the equation of the radiative transfer. As Co-Investigator of the Voyagers IRIS experiment he utilized all the data collected over the twelve years of the mission to study the He abundance in the giant planets and to provide a global interpretation of the observations to obtain the elemental and isotopic abundances in the giant planets and to study the thermal structure, the composition and the aeronomy of the Titan atmosphere.

Gautier was the prime supporter of the Cassini mission: he devoted his effort to convince the planetology community and the political authorities on both sides of the Atlantic of the unique opportunity for an in-depth exploration of the Saturn system and, in particular, of Titan. After the approval of the mission, he was selected Interdisciplinary Scientist of the Huygens Mission and, in preparation of the in situ exploration of Titan by the Huygens probe, he continued to investigate the nature of this major satellite of Saturn by scanning the whole electromagnetic spectrum available from the Earth with ground based telescopes.

Gautier applied the same observational techniques to the ground based studies of the atmosphere of the giant planets and, by taking advantage of the SL9 impact, to increase the knowledge of the structure of the Jupiter atmosphere. Furthermore, he studied the planetary oscillations and, as a consequence, the internal structure of Jupiter and Saturn.

One of the most important subjects of research in which Daniel Gautier is still providing important contributions is the determination and the interpretation of the D/II ratio both in giant planets as well as in the Protosolar nebula.

Newsletter 59, 37, 1996