New York: Scientists investigating evidence of water in Martian soil have found that the bulk soil on the Red Planet likely contains iron sulfates bearing chemically bound water that could be playing a major role in hydrating martian soil. "This is exciting because it's contributing to the story of water on Mars, which we've used as a path for our search for life on Mars," said study co-author Nicole Button from Louisiana State University. The authors expanded on previous work, which explored the chemical association of water with sulfur on Mars globally. They also characterised how, based on the association between hydrogen and sulfur, the soil hydration changes at finer regional scales. Using data collected from the 2001: Mars Odyssey probe, the researchers published the results of their analysis in the Journal of Geophysical Research: Planets. The study revealed that the older ancient southern hemisphere is more likely to contain chemically bound water while the sulfates and any chemically bound water are unlikely to be associated in the northerly regions of Mars. The team considered several existing hypotheses in the context of their overall observations, which suggest a meaningful presence of iron-sulfate rich soils, which are wet compared to Mars' typically desiccated soil. This type of wet soil was uncovered serendipitously by the Spirit Rover while dragging a broken wheel across the soil in the Paso Robles area of Columbia Hills at Gusev Crater. Among these hypotheses, the researchers identify acid fog and hydrothermal processes as more consistent with their observations than efflorescence, even though the sensitivity of Odyssey's Gamma Ray Spectrometer to elements, but not minerals, prevents a decisive inference. Hydrothermal sites, in particular, are increasingly recognised as important places where the exchange between the surface and deep parts of Earth's biosphere are possible. This hypothesis is significant to the question of martian habitability.