MISIP-2024 Project-1 – Project 1: Rheological measurements of Martian slurries
Andrea Caccia 1 , Jun Kameda 2

International Research School for Planetary Sciences, University ofPescara/Chieti “Gabriele D’Annunzio”; 2 Institute of Planetary Materials, Okayama
University1

Mars is certainly the most studied body of our Solar System aside from Earth. The amountof data available about its surface and its interior is extremely wide and, in most cases,extremely accurate. However, very speci�ic and precise data about its surface composition
is available only for very restricted areas where landers have been sent, and often times
Remote Sensing data (e.g. CRISM) doesn’t give back accurate values due to interferencesfrom the atmosphere or Martian dust that may alter the values read by the instrument.
Therefore, indirect methods of measuring Martian sur�icial mineral composition are
extremely important and valuable to obtain data that can be compared with different
datasets and provide a good measure of the goodness of the parameters used in research.
In our study, we ran several rheological measurements on Martian simulants (MGS-1,MGS-1C, MGS-1S and mixtures of MGS-1 and MGS-1C) so that we could understand theresponse of Martian surface to the varying of several parameters. In the speci�ic, weobserved the changes occurring in the samples when varying the water content (andtherefore the solid fraction), the Temperature, the salinity and when applying anoscillatory motion resembling tectonic movements.
Our analysis focused on Yield Stress and Viscosity analysis, and we found that they bothincrease exponentially when increasing the solid fraction of the samples, while they bothincrease at a slow rate when decreasing its Temperature. As for the salinity content, weran rheological measurements using brines with varying molar fractions of MgCl2, CaCl2and NaCl but with the amount of data we obtained, we couldn’t �ind a de�inite
relationship between molar fractions and rheological parameters (Yield Stress andViscosity), except for the case of NaCl that showed a slight linear decrease in suchparameters when increasing the Molar fraction of the chloride in the brine.
Lastly, we ran an oscillatory test to evaluate the sensitivity of such samples to seismic
movements, and we found that the samples are relatively resistant to liquefaction as byvarying the solid fraction at a T of 20°C, the Crossover Strain % settles at around 10%, avalue that is above the accepted values for Martian geological activity and that allowed
us to rule out this component as impactful in computational models of debris �low.
Once these values were obtained, we compared our results with Yield Stress andViscosity values obtained by Naruse et al. in 2016 from inverse modelling of a lobate
deposit in Protonilus Mensae. We found a very good match for the yield stress value of asample composed of 20% Smectite and 80% MGS-1 simulant, but the viscosity values forthis sample were quite far apart. This suggested that further experiments varying
salinity and T conditions of the simulant are required to fully understand thecomposition and conditions of Martian surface in that location.
Thanks to our data and the comparison with the data gathered by Mangold et al. in 2003,
we were also able to determine that there is a very high probability that clays are asigni�icant component of Martian most sur�icial layers as all of our measurements of
Yield Stress and Viscosity run on samples containing such component fell within therange that have been highlighted as most representative of Martian surface.

Even though this work did not succeed in �inding the sur�icial composition of Martian
terrain in the selected area, it highlighted a very promising experimental method to obtainsuch data in future studies.