Possibility of recent subterranean volcanism on Mars

The Martian South Pole. A new study in Geophysical Research Letters argues that there must be an underground heat source so that liquid water can be present under the polar ice cap. Credit: NASA.

A study published in the journal Science last year indicated that liquid water is present under the south polar ice cap of Mars. A recent study in the AGU journal Geophysical Research Letters now argues that there must be an underground heat source so that liquid water can be present under the polar ice cap.

The new research does not matter if the liquid water exists. Instead, the authors suggest that the recent magmatic activity – the formation of a magma chamber in the last hundred thousand years – must have taken place beneath the Martian surface so that there is enough heat to produce liquid water under the one and a half kilometer thick ice cap. On the other hand, the authors of the study argue that there are no new magmatic activities below the surface of Mars when there is likely to be no liquid water under the ice cap.

"Different people may take different paths, and we're really interested in how the community reacts," said Michael Sori, a research associate at the University of Arizona's Lunar and Planetary Laboratory and co-lead author of the new paper.

The potential presence of recent underground magmatic activity on Mars gives weight to the idea that Mars is an active planet, geologically speaking. This fact could give scientists a better understanding of how planets evolve over time.

The new study aims to stimulate debate about the possibility of liquid water on Mars. The presence of liquid water on the Red Planet has implications for potential life outside the Earth and could also serve as a resource for future human exploration of our neighboring planet.

"We believe that if there is life, it probably needs to be protected underground from radiation," said Ali Bramson, a research associate at the University of Arizona's Lunar and Planetary Laboratory and co-author of the new paper. "If magmatic processes are still active today, they may have been more prevalent in the recent past and could provide a broader basal melt. This could create a more favorable environment for liquid water and potentially life. "

Examine the environment

Mars has two huge ice sheets on its poles, both of which are a few kilometers thick. On Earth, it is common for liquid water to be under thick ice sheets, with the heat of the planet causing the ice to melt where it meets the earth's crust.

In an article published in Science last year, scientists said they discovered a similar phenomenon on Mars. They claimed that radar observations found evidence of liquid water at the base of Mars' south polar ice cap. However, the Science study did not address how the liquid water could get there.

Mars is much cooler than the earth, so it was unclear what kind of environment is needed to melt the ice at the bottom of the ice cap. Although previous research has investigated whether liquid water could be present at the base of Mars ice caps, no one had investigated the place where the Science study claimed to have discovered water.

"We thought there was a lot of room to find out if [the liquid water] Is it really, what kind of environment would you need to be able to melt the ice at all, what temperatures would you need, what geological processes would you need? Because under normal conditions, it should be too cold, "Sori said.

In search of the heat

The authors of the new study initially assumed that the detection of liquid water under the ice cap was correct, and then worked out which parameters were necessary for the presence of the water. They performed a physical modeling of Mars to understand how much heat is coming from inside the planet and if there is enough salt on the bottom of the ice cap to melt the ice. Salt significantly lowers the melting point of ice, suggesting that salt at the base of the ice cap could have melted.

The model showed that salt alone would not raise the temperature high enough to melt the ice. Instead, the authors suggest that additional heat must come from within Mars.

Publication: Michael M. Sori et al. "Water on Mars with a grain of salt: anomalies of basal ice melt at the South Pole today require anomalies of heat," Geophysical Research Letters, 2019; doi: 10.1029 / 2018GL080985


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