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dissertation (2)


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2020 (2)

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Dissertation
Heat Effect of Meteorite Impacts on the Degassing of Methane Trapped in Mars' Icy Soil
Authors: --- --- --- --- --- et al.
Year: 2020 Publisher: Liège Université de Liège (ULiège)

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Abstract

This master's thesis is devoted to assess whether a small impactor can lead to destabilization of clathrates and degassing of methane. Therefore, the increase of temperature as a result of impact energy is theoretically and numerically investigated. First, a discussion on the theoretical model, which is used to calculate the temperature increase following the impact event as a function of the impactor radius, velocity and impact angle, is presented. A comparison study of the two theoretical models considered in this study, Gault-Heitowit and Murnaghan equation of state, is then proposed. The Martian subsurface temperatures are also calculated from the heat equation using the Crank-Nicholson method. The sensitivity of temperature predictions on the thermal conductivity is investigated. The impact-induced temperatures are then added to the initial subsurface temperatures for different case studies. The final step consists of verifying if the temperature at a certain depth allows the destabilization of methane clathrates, and thus degassing of methane, both for equatorial and polar regions, for different thermal conductivities of the subsurface (ranging from 0.039 W/mK to 2.5 W/mK), radii (0.06 m, 0.12 m and 0.20 m) and velocities (8 km/s, 10 km/s and 12 km/s) of the impactor.


Dissertation
Multiphysics simulations of a gravimeter instrument using COMSOL Multiphysics and MATLAB
Authors: --- --- --- ---
Year: 2020 Publisher: Liège Université de Liège (ULiège)

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Up to date, no dedicated gravimeter instrument has been included on any probe to a small planetary body. The aim of the GRASS (Gravimeter for Small Solar System bodies) project at the Royal Observatory of Belgium is to fill this gap by developing an instrument capable of precise gravity vector measurement from the surface, in small gravity fields of 10^-3 - 10^-5 m/s^2. In the near future, the GRASS gravimeter is proposed to be a part of the HERA mission to the binary asteroid system Didymos. This work addresses the development of a model aiming to simulate the measurement of the gravimeter after landing on Didymos' secondary body, and an initial evaluation of the measurement feasibility and accuracy using the developed model.

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