Mars May Have Water Bound to Sulfates in Its Soil

A new analysis of Martian chemical maps has revealed that there may be water bound to sulfates in the soil on Mars. Scientists have discovered a spatial association between the presence of sulfur and hydrogen found in the soil.

The researchers analyzed elemental data from the Gamma Ray Spectrometer onboard the Mars Odyssey orbiter. This indicated that within the southern latitudes of Mars, sulfur compounds are a key hydrated phase. This was revealed in part by water-to-sulfur molar ratios that fell within expected ranges corresponding to hydrated sulfate compounds. In fact, the molar ratios were seen over 80 percent of Mars' southern hemisphere. Scientists believe that sulfate compounds, acting as primary contributors of H2O, may influence modern water-driven processes on Mars.

"Sulfur variation plays an important role as a control on inferred fluid pH, alteration environments, and water activity while the variation in hydration state reinforces the compelling possibility of H2O bound primarily in sulfates in the southern hemisphere," said Suniti Karunatillake, one of the researchers, in a news release. "This applies specifically to bulk soil at decimeter depths, including the possibility that geochemical processes of iron sulfate-rich Paso Robles soil in Gusev Crater may have been more common at regional scales in ancient Martian terrain than previously appreciated."

The scientists hope that further observations with the Curiosity rover in Gale Crater could actually reveal a bit more about aqueous processes on Mars. For example, recent analyses of "Rocknest" soil samples taken by Curiosity suggest complementary modes of soil hydration in the Gale Crater area.

The findings are published in the journal Geophysical Research Letters.

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