Unravelling the nature of the polyhydrated sulfate deposits on Mars

Hydrated sulfates are likely to be the dominant water reservoir in the equatorial region of Mars forming massive stratified deposits. Hence their detailed mineralogical characterisation is likely critical to understand the aqueous history as well as the present-day equatorial water cycle of our neighbouring planet. MgSO4·4H2O is the most promising candidate to form the bulk of the equatorial sulfate deposits whereas FeSO4·4H2O appears to be unstable under martian surface conditions. We have recently carried out Synchrotron XRD of both compounds between 85 – 300 K, revealing interesting intrinsic patterns of behaviour and differences between the Mg and Fe compounds. To explore this further, we propose to characterise FeSO4·4H2O and MgSO4·4H2O down to 10 K on HRPD and to determine the stability of the aforementioned compounds under simulated martian surface conditions on I11.