2:00 PM - 2:15 PM
[PPS02-02] Simulating the Lunar Soil: a Japanese Lunar Soil Simulant FJS-1 and Its Properties
Keywords:Lunar soil, Soil simulant, FJS-1, Soil simulant properties, Frozen soil
In order to offer opportunities for the community to perform ground tests, we have manufactured a lunar soil simulant, called FJS-1. The investigation of FJS-1 shows that many properties of FJS-1 lies close to the data collected from Apollo samples. For instance, the particle size distribution lies below 2 [mm]; the median particle size is between 70 and 75 [micro-m]; the shear strength, i.e. cohesion c, is 0 to 10 [kN/m2]; and the internal friction angle, phi, is 30 to 50 [deg]. The chemical composition is also close to Apollo samples with slight difference that FJS-1 contains more ferric oxide and Alkaline components than Apollo samples.
In addition to the basic properties, we started investigating the strength of frozen lunar soil using FJS-1. Determining the optimized configuration of a sampler such as a drill or an excavator needs the information of actual lunar soil; however, nobody knows the actual state, in other words, the ground truth of lunar water/ice yet. We therefore decided to investigate the strength of frozen soil, utilizing FJS-1, for the future use for drill or excavator designs. The qualitative observation from our first experiment is that the frozen FJS-1 at temperature below 0 [degC] became slightly loose when FJS-1 contained 0.5 to 1.0 [wt%] of water, and that the strength drastically increased above 2 [wt%]. We will conduct more experiments to collect a set of frozen soil strength to offer the estimates of the strength of lunar soil for future lunar exploration missions.