A SEMI-EMPIRICAL MODEL OF THE DEPENDENCY OF ATMOSPHERIC
ESCAPE ON THE PLANETARY MAGNETIC MOMENT AND SOLAR WIND PRESSURE
Mrs. Maria Luisa Alonso Tagle (BIRA-IASB, Brussels, Belgium)
Romain Maggiolo (BIRA-IASB, Brussels, Belgium)
Herbert Gunell (Umeå University, Umeå, Sweden)
Gäel Cessateur (BIRA-IASB, Brussels, Belgium)
Johan De Keyser (BIRA-IASB, Brussels, Belgium)
Giovanni Lapenta (Centre for Plasma Astrophysics - KU Leuven, Leuven, Belgium)
Viviane Pierrard (BIRA-IASB, Brussels, Belgium)
Ann C. Vandaele (BIRA-IASB, Brussels, Belgium)
The role of the planetary magnetic field in the stability of planetary atmospheres remains debated. Gunell et al. (2018, doi:10.1051/0004-6361/201832934) developed a semi-empirical model of atmospheric escape for Venus-, Earth- and Mars-like planets. This model uses in-situ measurements and physical considerations to model the effect of planetary magnetization on the atmospheric loss rate. It shows that atmospheric loss rate can be higher for magnetized planets than unmagnetized ones over a wide range of magnetic moments for current solar and atmospheric parameters.
We further develop this model in order to consider other parameters that drive atmospheric erosion, such as solar wind pressure. Physical assumptions are made to describe the effect of the solar wind pressure on each erosion mechanism. The main objective is to reproduce early planetary and solar conditions in order to constrain the role of the planetary magnetic field and solar wind pressure on atmospheric loss over geological time scales.
We summarize previous results, describe the semi-empirical model, and discuss its future development. We show results illustrating how the model can be used to study the past evolution of the atmosphere of the rocky planets in the Solar System. We are particularly interested in the peaks of the erosion rate and its possibility of occurrence in the past.
