Guarded Torus - Line Heat Source: Use and Comparisson

In the past few years scientists developed an increasing interest in the structure and the behaviour of extraterrestrial surfaces. Various missions include landing devices to investigate the physical properties of surfaces of planets, moons and comets. Comets are playing a main role as targets of these investigations. They are composed of ice, dust and organics and it is assumed that comets consist of the basic material out of which the solar system was formed. The properties at the surface and the upper layers of comets as well as their change during the approach to the sun are therefore of special interest. The thermal and mechanical properties of the comet 67P/Churyumov-Gerasimenko and their changes should be measured with the MUPUS-probe, one of the instruments on the Rosetta lander Philae. This project will concentrate on the thermal properties of cometary surfaces. Therefore different methods to measure the temperature and the thermal conductivity will be compared, the main focus will lie on the Line Heat Source (LHS) and the Guarded Torus (GT) method. Measurements with different sensors under atmospheric pressure and under vacuum conditions will be done (at room temperature and at temperatures below the sublimation point of ice). The experimental results will be compared with the results obtained from numerical simulations. In the framework of these studies, numerical thermal models developed by the applicant will be improved and up-graded, and new models will be developed. The use of these models should lead to a better understanding of the possible operation modes of MUPUS and due to this ease the operation of the mission. The limited time and energy for measurements at the comet can therefore be used in a better way. The results of the experiments and models should further support the interpretation and analysis of the data obtained from the MUPUS probe and due to this help to minimize errors in the data analysis. Based on the expected results of the proposed project, the operational modes of MUPUS as well as the analysis of the obtained data should be simplified, improved and made more accurate. Furthermore the possible application of an improved thermal probe future missions (e.g. MoonNext, MarsNext, asteroid missions) triggered by these results will be assessed.