Geotechnical Research for spAce enVironments using an Innovative Tower Experiment

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As the number of space missions involving surface interactions increases, so does the need to understand the behaviour of planetary surfaces. The surface properties also are crucial for human exploration, and play a key role in the evolution of planetary bodies. In terrestrial geophysics and planetary exploration, two techniques are widely used for in-situ determination of soil mechanical properties: seismic sounding, and penetration testing. However, the GRAVITE PI hypothesizes that these techniques are not directly applicable for space exploration due to implicit assumptions that become invalid in low-gravity environments, and that this has resulted in erroneous interpretations of data from multiple space missions. Whereas others use limited experimental data points, numerical simulations or untested extrapolations, GRAVITE will build a unique high-performance, low and variable gravity laboratory to extensively explore, for the first time, the complex interactions between particle size, friction and cohesion in the response of granular materials to both small and large deformations, under vacuum, and in reduced-gravity conditions. The GRAVITE facility, capable of reaching gravity levels three orders of magnitude less than Earth’s gravity (in order to simulate small body surfaces), and of finely adjusting the gravity level of each individual experiment, will bridge an existing gap in facilities and provide exceptional experimental data covering a wide range of gravity conditions. The GRAVITE data from two custom experiments will be used to test the limits of existing theories, and validate new models accounting for previously unexplored regimes. As such, GRAVITE will provide the planetary science and exploration communities with much needed models that can be used to predict and interpret the behaviour of extra-terrestrial surface materials. The results will have direct applications to current and future space missions that interact with planetary surfaces.