Martian Water Might Vary From Region To Region

Mars, as seen by one of the Viking orbiters. NASA/JPL

The discovery of water on Mars has changed our approach to the Red Planet significantly. Water means that life, either extinct or living, may be present, and we need to be a lot more careful in our investigations.

But researchers from Louisiana State University decided to take a step back and have a look at the bigger picture. Using NASA’s 2001 Mars Odyssey satellite, the scientists looked at the bulk soil composition of Mars and discovered that iron sulfates might play a key role in hydrating the dry Martian terrain. A paper with these findings is published in the Journal of Geophysical Research: Planets.

2001 Mars Odyssey, named after Arthur C. Clarke’s novel, has a Gamma Ray Spectrometer on board. As it orbited the planet, it was able to detect the composition of the ground to a depth of 0.5 meters (1.6 feet), deeper than any other orbiter or robotic explorer on the surface.

“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,” Nicole Button, an LSU Department of Geology and Geophysics doctoral candidate and co-author of the study, said in a statement.

The team has previously shown the association between sulfur and water, so they used this data to estimate the hydration of the soil, and discovered that the southern hemisphere is richer in water than the northern hemisphere. The differences don’t stop there: Soil hydration is higher at lower latitudes in the south, but in the north, it increases with latitude.

Soil thickness, ice presence and depth, atmospheric circulation, and sunshine can explain the current difference in the amount of water in the soil of different regions.

The team also tried to understand how the Martian soil became rich in iron sulfates. There are several hypotheses for its formation, such as hydrothermal activity, acid fog from the extinct volcanos, and even efflorescence, which is how salt deposits form in basements or on brick walls.

The hydrothermal activity and acid fog seem to be the best explanations for what they see, but since the spectrographs can only measure the density of elements and not the minerals, the team is still uncertain.     

“Our story narrows it to two hypotheses, but emphasizes the significance of all of them,” said Professor Suniti Karunatillake, also from LSU and a co-author of the study. “The depth and breadth of these observation methods tell us about global significance, which can inform the big question of what happened to the hydrologic cycle on Mars.”

This work is giving us a road map for Mars. Wherever water is hiding, life might be hiding too.

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