Assessment of the early stages of rehydration observed by sorption isotherm and 1H-NMR and plant growth tests for Martian regolith simulant MGS-1

The early stages of gaseous phase rehydration of the Mars global simulant (MGS-1) were studied using hydration kinetics, sorption isotherm, and proton nuclear magnetic resonance ( 1 H-NMR) spectroscopy, whereas initial plant growth tests in media containing MGS-1 were assessed by microbiotests and measurement of plant biometry -seedling root length and biomass accumulation.MGS-1 is a Martian regolith analogue, whose hydration kinetics were described by a two-exponential function, and the sorption isotherm was fitted by the Dent (GAB) model.The number of empty binding sites (1/b 1 ) for humidity h = 1 was 1.59%, indicating the elevated hydrophobicity of the sample.The free induction decay signals (FID) were fitted by the superposition of a Gaussian component, and an exponentially decaying mobile proton signal component.The 1 H-NMR spectra were fitted by a Gaussian component and a narrow Lorentzian line.The NMR signal was attenuated by the presence of paramagnetic ions, particularly Fe 2+ .A microbiotest of the initial growth of six plant species in MGS-1 mixtures with an inert substrate, i.e. perlite, showed high toxicity of the regolith simulant.The volumetric ratio of 2:1 (MGS-1:perlite) caused plant death and a statistically significant decrease in biomass accumulation by the tested plants.Triticum aestivum best tolerated the MGS-1 substrate.