Digging and Driving in Moon Dirt
Design and flight data from Apollo's Lunar Roving Vehicles and Soviet Lunokhod rovers are a treasure for innovating new lunar locomotion and developing unprecedented excavation machines. Highly accurate lunar soil simulants were developed based on flight data and returned samples. Our team accesses the best of these simulants and is using them for rover and excavator experiments.
Compaction and Soil Preparation
Having the right soil grains is not enough to provide a good simulation of the lunar terrain; the soil must be prepared in way that best replicates the conditions found on the moon. The two main variables to achieve this are moisture (usually dry) and compaction. To test the effects of compaction we conduct a series of penetration tests on lunar simulants. Above are graphs of the initial results obtained from loose lunar simulant and simulant that has been compacted by ten tamps with a weighted steel plate. The sinkage vs. pressure relation is fairly linear; this is a trait of the simulant being used. Soil behavior becomes more predictable as compaction increases; this may be due to the random locations of soil voids in loosely prepared soil. We have continued testing at these and other compaction levels. The results correspond with what should be expected from theory and previous research. Further testing is being done to develop a systematic soil preparation method.