Volcanic activity under the surface of Mars? | Space


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Circular and circular white spot on a red-brown plant: south polar ice cap.

Is there volcanic activity on Mars? An underground lake located under the south polar ice cap may indicate that there are some. Image via NASA.

Mars has the largest known volcanoes in the solar system, which shows that it was once very geologically active. But so far, the available evidence suggests that the planet's period of volcanic activity ended millions of years ago – these huge calderas have been dormant for a very long time.

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But now, it seems that can not enough After all, there may still be residual activity in the subsoil, according to a new paper peer reviewed in Geophysical Research Letters. Extract from the summary of the document:

Recent radar observations from the European Space Agency's Mars Express probe have been interpreted as evidence of ice melting at the south pole of Mars. We model the temperatures in the basement to determine the conditions necessary to obtain liquid water at the base of the ice cap. The salts lower the melting point of the ice, calcium perchlorate generating the lowest temperatures that can be reached. However, even if there are local concentrations of large amounts of these salts at the base of the southern polar ice, typical Martian conditions are too cold to melt ice. We find that a local heat source in the crust is needed to increase temperatures and that a magma chamber located less than 10 km from the ice could provide such a heat source. This result suggests that if the interpretation of observations by liquid water is correct, the magmatism on Mars could have been active very recently.

Cut of the surface. Horizontal white line, thick blue line shorter.

The first ever liquid water lake discovered on Mars? The glossy horizontal feature of this image represents the icy surface of Mars. The stratified deposits of the south polar – layers of ice and dust – are visible at a depth of about 1.5 km. Below is a base layer that in some areas is even brighter than surface reflections, highlighted in blue. The analysis of the reflected signals suggests a liquid water. Image via ESA / NASA / JPL / ASI / Univ. Rome; R. Orosei et al. 2018.

The study's findings are linked to a previous document from last year, which presented evidence of a large subsurface liquid water lake currently beneath the southern polar ice cap. The new study indicates that for such a lake to exist, there must be a heat source deep below the surface – a recent magmatic activity in recent hundreds of thousands of years. It's very recent geologically and such heat could still be there today. Michael Sori, associate researcher at the Lunar and Planetary Laboratory (LPL) at the University of Arizona and co-author of the new paper, acknowledges that the new document will spark debate:

It may be different for different people, and we are really interested in the community's reaction.

The big question is, of course, what can this mean for the pursuit of life? If there is both liquid water and a source of heat that would greatly increase the chances of a kind of life – though probably still microbial – existing beneath the surface. According to Ali Bramson, Postdoctoral Research Associate, also at LPL, and co-lead author of the new article:

We think that if there is a life, it will probably have to be protected in the basement of radiation. If magmatic processes are still active today, they may have been more common in the recent past and could provide a more extensive basal melting. This could provide a more favorable environment for liquid water and thus, perhaps, for life.

Sectional view of a thick clear blue ice, a dark blue spot underneath, a vertical drill hole.

It is believed that the alleged underground lake on Mars is similar to Vostok Lake in Antarctica. But the Martian Lake would probably need heat from volcanic magma to stay liquid. Image via the National Science Foundation.

A liquid water lake beneath the southern polar ice would not be too surprising, as they also exist beneath the polar caps of the Earth. But scientists do not know how they would stay liquid on Mars, because the planet is generally much colder than the Earth. As Sori noted:

We thought there was plenty of room to know if [the liquid water] is what kind of environment would you need to melt the ice, what temperatures would you need, what type of geological process would you need? Because under normal conditions, it should be too cold.

So, if the water really exists, as announced last year, what's keeping it liquid? The research team of the new document conducted experiments on modeling the subsurface of Mars, particularly to determine if salts alone would be sufficient. They concluded that salts alone would probably not be able to raise enough temperature at the base of the ice cap, and that extra heat would be needed.

So where would this heat come from? The most plausible source would be an underground volcanic activity – a magma chamber under the ice cap. The team estimated that the magma had risen to surface for about 300,000 years, but did not reach the surface, but remained in the chamber. The heat of the chamber melted the bottom of the ice cap, forming the lake. But above all, we should always provide this heat aujourd & # 39; hui, not just hundreds of thousands of years old. As Bramson has noted:

This would imply that there is still today a formation of magmatic chambers active in the interior of Mars and that it is not just a dead place. , cold, internally.

Cup of a volcano with many volcanic features, including a magma chamber.

Illustration showing how a magma chamber feeds the volcanoes of the Earth. Similar magmatic chambers can feed underground water lakes on Mars. Image via Wikimedia Commons / William Crochot / Creative Commons License Attribution-Share Alike 4.0 International.

The new article will help scientists better understand how underground lake water has arrived – if it is confirmed – and how it can stay fluid, according to LPL professor Jack Holt:

I think it was a good idea to do this kind of modeling and analysis because you have to explain the water, if it's there, it's really a crucial part of the puzzle. The original document has just left it in abeyance. There might be water there, but you have to explain it, and these guys have done a really good job saying what is required and that the salt is not sufficient.

In conclusion: a new study indicates that volcanic activity may still be present in groundwater on Mars, which would help to explain the findings of a previous study providing evidence of a large underground lake under the ice at south pole of Mars. Both discoveries could have important implications in the search for life on Mars.

Source: Water on Mars, with a grain of salt: local heat anomalies are needed for the basal melting of ice at the South Pole today


Paul Scott Anderson

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