Geotechnical assessment of terrain strength properties on Mars using the Perseverance rover's abrading bit

To date, instruments for measuring geotechnical properties have been absent from Mars exploration missions. This paper examines the use the Mars 2020 Perseverance rover’s abrading bit tool to perform regolith strength measurements. The Perseverance rover’s abrading bit has a similar form factor to a Bevameter, a tool commonly used to collect engineering geotechnical data to assess terrain traversability. To demonstrate the use of the abrading bit to characterize soil strength, a portable testbed that mimics the flight system has been designed and built using commercial off-the-shelf components. The testbed comprises an 80/20 housing, avionics box, and drill feed mechanism. Additionally, a data-processing pipeline was developed to convert raw measurements to soil strength. Tests were performed on three characterized simulants with different mechanical properties. The results show that the abrading bit is capable of making shear and bearing strength measurements and demonstrate, for the first time, the ability to perform controlled geotechnical analysis using a standard science instrument.