Measuring Thermo-Mechanical Properties of Cometary Surfaces: In Situ Methods

Thermal and mechanical properties of cometary ices are closely associated with eachother. Both are largely determined by the texture (porosity, grain size distribution,grade of sintering) of the material. The surface probe of the Rosetta mission to comet46P/Wirtanen (Rosetta Lander) will for the first time measure these thermo-mechanical keyparameters in situ, using a hammering device, a drill, and anchors to be shot intothe ground by pyrotechnical means. Several of these components are associated to theexperiment MUPUS (MUlti-PUrpose-Sensors forsurface and sub-surface science). The development of this instrument has now reached amature state, as the flight model is already delivered and integrated with thespacecraft. We describe the main aspects of the experiment, outline the evaluationmethods, and show representative results from test measurements.