ROCSS

Space bodies without atmosphere are numerous in our solar system, including asteroids, several natural satellites and one planet. Yet we still do not fully understand how and where these bodies formed and how their formation is related to the evolution of our solar system. In this project, we hypothesize that part of the formation and evolution mysteries of the atmosphere-less bodies may be deciphered in their outermost surface. That surface is generally made of multi-minerallic rocks and regoliths (layer of unconsolidated rock fragments). Understanding the physical mechanisms that created these materials is crucial to understand the processes that created the atmosphere-less bodies and contributed to their evolution over the last 4.5 billion years. ROCSS thus focuses on the characterisation (i.e., analysis of conductivity, density, porosity, degree of roughness, etc.) of the surface of atmosphere-less bodies and on the processes that sculpted it. For that, we developed a new method to better analyse the astronomical infrared observations of planetary surfaces that are acquired with large telescopes from the ground, from space, and by in situ space missions such as OSIRIS-REx (NASA) and Hayabusa2 (JAXA).
The method is a novel numerical model allowing the analysis of both the solid and the radiative conductivity of complex materials, such as those expected to form the surface of atmosphere-less bodies. Using this new model, we could for instance estimate for the first time the radiative thermal conductivity of polydisperse particulates (Ryan et al. 2019). We are now using the model to characterize the surface of the asteroid (101955) Bennu, target of the NASA’s sample return mission OSIRIS-Rex in 2019 and 2020.