Adsorption driven regolith-atmospheric water vapor transfer on Mars: An analysis of Phoenix TECP data

by Farris, Holly N.; Conner, Miguel B.; Chevrier, Vincent F.; Rivera-Valentin, Edgard G.

We analyze Phoenix Thermal and Electric Conductivity Probe (TECP) instrument data and previous experimental data to present constraints on the parameters for regolith-driven adsorption at the Phoenix landing site. Modeling Brunauer-Emmett-Teller (BET) adsorption of the data across Mars-relevant materials yielded fairly constant surface coverage and enthalpy values, theta=0.336, corresponding to 2.96 x 10(-7) kg of H2O/m(2) and Delta H = 52.783+/-1.206 kJ/mol, respectively. With our modeled BET adsorption coefficient, C=89.4, and ideal specific surface area, SSA=1.7 x 10(4) m(2)/kg, we conclude that the regolith at the Phoenix landing site is most likely a mixture, which we bracket with a range of possible adsorption conditions. Ultimately, we explain adsorbed water content in the regolith at the Phoenix landing site and thus, adsorption being driven by localized, diurnal variations in the relative humidity.

Journal
Icarus
Volume
308
Year
2018
Start Page
71-75
URL
https://dx.doi.org/10.1016/j.icarus.2017.08.002
ISBN/ISSN
1090-2643; 0019-1035
DOI
10.1016/j.icarus.2017.08.002