Volcanic Exhalation of Sulfur on Mars
We know from in situ bulk chemical and mineralogical analyses, remote sensing data, and geochemical models that the Martian crust is sulfur(S)-rich, exceeding the S content of terrestrial basalts by almost an order of magnitude. Ultimately, S is delivered to the crust by volcanic exhalation of SO2 and H2S gases. On Earth, volcanic ash, spewed along with other gases, can adsorb up to 30 % of the exhaled S gas species with subsequent deposition. The above maps show the concentration of S and Cl on Mars (from Gamma Ray Spectrometer (GRS) on Mars Odyssey). A large sedimentary deposit of likely pyroclastic origin on Mars called the Medusae Fossae Formation (MFF) has the highest concentration of S and Cl. In our recent work, we estimated how much sulfur would have been released to the Martian atmosphere by explosive volcanism. Based on reasonable terrestrial analog estimates that the MFF adsorbed, at maximum, 30% of the exhaled S gas species, we find that a significant amount of S (>10^17 kg) would have been delivered to the atmosphere over the time it took for the MFF to be deposited on Mars. S-gases are greenhouse gases, thus, if the MFF was deposited on a short time scale, then climatic conditions enabling the existence of liquid water may have been maintained by this amount of exhaled S gases. (Link to the paper).
Hidden Reservoirs of Water-Ice On Mars
Recently, along with a few coauthors, I used the Martian gravity and topography data to find the density of the north polar cap of Mars (pictured above). The north polar cap of Mars consists of thick sheets of extremely pure ice called the north polar layered deposits (white unit in the image above) and the sand-rich basal unit. Radar data has been able to provide information on the composition of the north polar layered deposits, however, the composition of the basal unit is not entirely clear. In this study, I used gravity data of Mars to estimate the density of the basal unit. We found relatively low density for the BU which suggests that it may contain more than 50 % ice. Thus, our study suggests that the basal unit may one of the largest sources of water ice on Mars. Paper coming out soon.