Volatile elements and Mars
Many of the projects focused on Mars proposed at the laboratory and presented in the Mars transverse axis, are related to volatile speciation and cycling and will be discussed in synergy with it. They mostly concern water and carbon in the Martian crust and the study, from surface observations, of water-rock interactions in conditions ranging from shallow conditions to hydrothermal activity, and the experimental study of gas hydrates and clathrates. Clathrates are non-stoichiometric compounds consisting of crystalline networks of hydrogen-bonded water molecules (hosts) encaging gas molecules (guests), which are believed to have been the dominant CH4-bearing phase in the nebula from which the outer planets and satellites formed, and are thought to be largely present in Mars crust. Localized release of methane observed by spatial probes in Mars atmosphere is thought to be linked to methane clathrate destabilization at depth. One key project concerns the study of their P-T destabilization conditions (PHYSIX). The gas release under planetary relevant P-T conditions will be directly probed in laboratory and large scale facilities (mainly synchrotron and neutron scattering experiments).
The distribution and speciation of volatiles, H and halogens, on Mars will also be learned by studying meteorites (ROCKS, MP3). In particular, the loss of water at the surface of Mars due to UV irradiation can be addressed using H-isotopes in various minerals in Martian meteorites. The high spatial resolution of the NanoSIMS offers the capability to constrain the evolution of the hydration of the surface of Mars throughout its history.
Finally, the diversity of studies of volatile species and volatile-related processes developed in the laboratory (volatiles as trace elements, C- and N-phases at various P and T, fluid-rock interactions on Earth and asteroids) provides a particularly suitable environment for the development of volatile studies on Mars.