A first achievement after several months of work, the submission of a first paper is definitely a major step in a PhD student's life. "I have been working on this manuscript for more than half a year", the author Maxime Grandin reveals. "I actually started this project during my Master's thesis, in early 2013. I am glad we managed to continue developing this model thanks to this collaboration SGO initiated with IRAP [Institut de Recherche en Astrophysique et Planétologie] in Toulouse through my PhD."
The paper is about a new approach for radio-occultation data analysis, based on the example of the radio science experiments onboard Mars Express. Radio-occultation experiments consist in probing the neutral atmosphere and the ionosphere of a planet using the propagation of radio waves between the spacecraft orbiting the planet and a receiver on Earth. As the radio wave propagates within the planetary envelope, it undergoes a slight deflection due to the varying refractive index of the medium. This deflection can be estimated via the residual Doppler shift which is measured at the receiver, compared to the expected Doppler shift for a straight-line propagation of the wave. "Usually, such measurements are treated as an inverse problem to retrieve the electron density profile in the ionosphere and the neutral density and temperature profiles in the lower atmosphere," Maxime explains. "But with the coauthors of this manuscript, who were my Master's thesis supervisors at IRAP and ESTEC [European Space Research and Technology Centre, Noordwijk, Netherlands], we decided to adopt a direct approach by simulating the ray propagation between the spacecraft and the ground receiver during an experiment, in order to try to reproduce the measurements."
No doubt that the PhD student was very eager to complete this first manuscript of his. Feverishly, as he got the green light from each of the coauthors, he undertook the submission process to a peer-reviewed journal in geophysics. The first paper is a special one, and the author needs taking a deep breath before clicking the final button. "I published my first paper as a Master's student, in the early 1980s," Esa Turunen recalls. "It was about a model I developed in Fortran 77 to describe the strongly-interacting matter with a two-phase approach. Particle physics! It took two years to complete the model; it was a very complex formulation," the present director of SGO recollects.
While the reviewing process runs its course, besides checking its status every other hour, the young PhD student will focus on a study about solar wind high-speed streams influence on the high-latitude ionosphere, which may bring him a second paper by the end of this year. Or at least so he hopes.