Using Percussive, Dynamic, and Static Soil Penetrometers to Assess Geotechnical Properties and the Depth to Ground Ice of the Mars and Lunar Analog Terrains on the Devon Island, Canadian Arctic

Abstract

In the summer of 2011, we used three geotechnical instruments to assess the ground conditions in planetary analog sites on the Devon Island, Canadian High Arctic. The instruments included Percussive Cone Penetrometer (PCP) developed by Honeybee Robotics, and the two off the shelf instruments: Dynamic Cone Penetrometer (DCP), and the Static Cone Penetrometer (SCP). The three systems differed by the methods the rod was driven into the soil. SCP used a reaction force provided by the operator to drive the rod into the ground, the DCP used a drop hammer, and PCP used a high frequency hammer (percussive) system.The three instruments were evaluated based on their ability to be used by astronauts and be deployed autonomously on planetary robotic platforms (e.g. rovers, hoppers). The SCP, although simple to operate, was limited to soft soils and its data was unreliable. DCP required two people to operate, was heavy, and though the data was reliable, it took a few minutes to obtain it. The PCP has proven to be very reliable, fast, and the data was obtained and plotted in real time. Hence, PCP is recommended as the optimum geotechnical tool for planetary exploration for either a robotic system or an astronaut.The tests were performed at the Drill Hill site within the Haughton Crater. The site was covered by the polygonal features, the telltale signs of water activity (freeze-thaw cycle) beneath the surface. The measurements were taken at the polygons junctions, sides, and the center. It was found the polygon junctions are the weakest, followed by polygon sides, and finally polygon centers (the strongest). The depth to ground ice at these three locations was 65 cm in each case.

Advances in Projectile Penetration Mechanism in Soil Media

“…To study the in-situ behavior of soil materials under impact penetration, other sophisticated experimental techniques such as photo-elasticity [113] and grain-scale particle tracking [114] have been developed. The results of impact penetration tests may also be used with greater accuracy and reliability for sub-surface investigations [115] and may replace the conventional cone penetration test. Other impact penetration applications include remote soil exploration (including extra-terrestrial), seismic monitoring and surveying, and post-construction exploration of the soil properties of large earth structures [116].…”