In the areas of aerospace and military industry, wheeled vehicles are expected to have the ability of passing various ground surfaces, including lunar soil, sand, marsh, mud flat, etc. This makes vehicle trafficability on soft ground become a very hot research topic. There are very a few difficulties in the present research of vehicle trafficability on soft ground, such as obtaining wheel-ground interaction information, inaccurate identification of soil mechanical characteristics parameters, and single evaluation index. In this paper, a novel approach of evaluating the vehicle trafficability on soft ground using wheel force information is proposed. As parts of the proposed approach, the methods of obtaining wheel force information, identification of soil mechanical characteristics parameters and integated method of trafficability evaluation, are discussed in detail. The proposed approach was validated through a practical test.

Many large cold traps exist at both lunar poles where temperatures never exceed 110 K annually, allowing the preservation of water ice. Much has been learned about these regions from orbital measurements, but in situ access is needed to truly understand the abundance, distribution, texture, and chemistry of volatiles that might be present in the regolith. We systematically studied the accessibility of the larger cold traps to wheeled vehicles from nearby staging areas. We calculated minimum energy routes for 20 north pole cold traps and 39 south pole cold traps >50 km(2) in area. At each, accessibility metrics were determined for paths into and out of the cold trap and for round trip paths that return to the same location. We found that 55 of the 59 cold traps are readily accessible without exceeding 25 degrees slopes. Smaller cold traps are generally more accessible than larger ones, with certain exceptions. The accessibility data set is presented graphically, in tabular form, and as ArcGIS shapefiles, all of which can be used to inform site selection and mission planning for future scientific and resource-focused activities. Plain Language Summary There are certain areas at the poles of the Moon which are cold enough to host ice deposits, but they have never been studied directly by robots or astronauts. In this study we determined how easy or difficult it would be for wheeled vehicles to get into and back out of coldest areas at the poles, which are found in topographic lows that sometimes have high slopes all around. We found that most of the cold areas can be driven into and back out of safely to nearby staging areas that have enough sunlight to recharge batteries. The smaller cold areas are generally easier to access, but some of the larger ones have safe, fast routes, especially for entry.

In a new era of lunar exploration, pyroclastic deposits have been identified as valuable targets for resource utilization and scientific inquiry. Little is understood about the geomechanical properties and the trafficability of the surface material in these areas, which is essential for successful mission planning and execution. Past incidents with rovers highlight the importance of reliable information about surface properties for future, particularly robotic, lunar mission concepts. Characteristics of 149 boulder tracks are measured in Lunar Reconnaissance Orbiter Narrow Angle Camera images and used to derive the bearing capacity of pyroclastic deposits and, for comparison, mare and highland regions from the surface down to similar to 5-m depth, as a measure of trafficability. Results are compared and complemented with bearing capacity values calculated from physical property data collected in situ during Apollo, Surveyor, and Lunokhod missions. Qualitative observations of tracks show no region-dependent differences, further suggesting similar geomechanical properties in the regions. Generally, bearing capacity increases with depth and decreases with higher slope gradients, independent of the type of region. At depths of 0.19 to 5m, pyroclastic materials have bearing capacities equal or higher than those of mare and highland material and, thus, may be equally trafficable at surface level. Calculated bearing capacities based on orbital observations are consistent with values derived using in situ data. Bearing capacity values are used to estimate wheel sinkage of rover concepts in pyroclastic deposits. This study's findings can be used in the context of traverse planning, rover design, and in situ extraction of lunar resources. Plain Language Summary Future explorers will be visiting pyroclastic deposits for research and resource extraction. However, the properties of the surface are not well known and it is unclear how well vehicles and humans are able to travel across these areas. Properties of 149 boulder tracks are measured in spacecraft imagery and are used to derive estimations for the strength of pyroclastic, mare, and highland area material from the surface down to similar to 5-m depth. Results are compared and complemented with soil strength estimates that have been derived based on in situ measurements taken during previous lunar surface missions. In all regions of interest, tracks have similar appearances, implying that the surface material has comparable properties. Generally, soil strength increases with increasing depth and decreases with higher local slope angles. At depth, pyroclastic deposits show equal or significantly higher strength in comparison to mare and highland areas and, therefore, might be equally trafficable at surface level. Calculations based on globally distributed spacecraft images agree with values derived from Apollo-era in situ data. Based on the soil strength, the sinkage of rovers in the areas of interest is estimated. Potential applications of this work include rover design and mission planning, infrastructure construction, and resource extraction.