280-11 Thermal and Physical Properties of Solid and Molten Martian Regolith Simulants

Session: Planetary Exploration and Education: How We Learn About Our Solar System and Beyond

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Crewed missions to Mars will likely require construction of infrastructure via In Situ Resource Utilization (ISRU), applying technologies such as sintering, melting, and additive manufacturing to Martian regolith. Considerable effort has been expended in developing ISRU technologies for lunar applications, using volatile-poor lunar regolith simulants. An important question is whether the same technology can work with oxidized, volatile-rich Martian regolith or whether its mineralogical differences may require different technology.  

We focused on 4 Martian simulants: MMS and Rocknest developed at NASA centers, and  MGS-1 and JEZ-1 developed by Space Resource Technologies (SRT).  We measured powder density using helium pycnometry; bulk and tap density using a graduated cylinder; loss oon ignition using a furnace and precision balance; heat capacity and enthalpies of fusion using differential scanning calorimetry (DSC); melt viscosity using rotating spindle viscometry (RSV); and thermal diffusivity and conductivity of quenched glasses using light flash analysis (LFA).

Particle density varied from 2680 kgm^-3 (Mars-1) to 3010 kgm^-3 (JEZ-1). Bulk densities (simulant poured into container) are 940 to 1440 kgm^-3 with 51 to 67% porosity. Tap densities indicate that 15-20% of this porosity is lost after 9000 taps, resulting in compacted bulk densities of 1200-1640 kgm^-3. During heating, all simulants show volatile outgassing below 400˚C, a glass transition between ~600̊˚C and 800̊˚C, and an endothermic melting peak between ~1100̊˚C and 1300̊˚C. The viscosity of molten MMS increases from 2.6 Pas at 1600˚C to ~300 Pas at 1150˚C, where minor crystallization was detected. These viscosities are similar to lunar highlands simulants (e.g. NUW-LHT-5M) but about 4 times higher than those of mare simulants (e.g. JSC-1A). Thermal diffusivity of glass made from MMS is low, ~0.6 mm²s^-1 at room temperature, decreasing to ~0.5 mm²s^-1 at 650˚C, which is similar to glasses made from various lunar simulants.  

Martian regolith simulants typically have much higher volatile contents (2.5 to 8.5 wt% loss on ignition) compared to lunar variants. The JSC Rocknest simulant, which may be the best mineralogical match to actual Martian regolith, is extremely difficult to work with due to its high volatile content (water and sulfate) that causes bubbling and crucible overflows on heating. This suggests that technologies developed for volatile-poor lunar regolith may not translate easily to working with volatile-rich Martian regolith.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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