New technique unlocks soil properties from space probes, avoiding costly sample returns
Scientists have validated a method to measure planetary soil strength using simple penetrometry tools—eliminating the need for expensive sample collection and laboratory analysis in space missions. The finding could dramatically reduce costs for lunar bases, Mars rovers, and future planetary exploration by allowing spacecraft to assess ground stability in real time.
Originaltitel: Exploring planetary regolith: deriving geotechnically meaningful properties from penetrometry
<p>Understanding the properties of planetary regolith is important for unravelling the origin and evolution of bodies in our solar system. On Earth, properties of regolith are identified in the laboratory through a variety of methods such as coring samples, shear tests, and triaxial tests. In space missions, these laboratory methods cannot be used, and one must rely on in-situ measurements for identifying soil mechanical properties. Penetrometers are perfect for this due to their small size, light weight and simple use. Penetrometers have been used on Earth to identify soil shear strength properties such as cohesion and angle of internal friction. However, results are highly dependent on the experimentally obtained data and the types of soil that are tested. In this paper, we use a model developed by Kang et al., that links penetrometry data to geotechnically relevant quantities such as the angle of internal friction, test this model using our own laboratory experiments, and compare this to known values as well as triaxial test results. We identified that for silica glass beads the effects of grain size and tip shape are very pronounced, with similar values of internal friction found in other sources and our triaxial tests. We observed that penetrometry can indicate similar angles of internal friction comparable to laboratory values for more irregular and angular sample materials such as the Phobos simulant used to prepare for JAXA's MMX mission. Our results suggest that a penetrometer could be used as a ‘poor man's triaxial test’ in planetary exploration.</p>