Mars has the largest known volcanoes in the solar system, showing that it was once very geologically active. However, the available evidence suggests that the volcanic activity of the planet ended millions of years ago – that these massive calderas were long inactive.
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But now it seems that may not be quite the case – there may still be residual activity underground, according to a new peer-reviewed paper in Geophysical Research Letters . From the summary of the paper:
The recent radar observations of the space probe Mars Express of the European Space Agency were interpreted as proof of melting under the ice at the south pole of Mars. We model the subsoil temperatures to determine the conditions necessary to reach liquid water at the base of the ice cap. Salts lower the melting point of ice, with calcium perchlorate producing the lowest temperatures at which melting can be achieved. Even if local concentrations of large amounts of these salts are present at the base of the south polar ice, typical Martian conditions are too cold to melt the ice. We find that a local heat source in the crust is required to increase temperatures, and a magma chamber within 10 km (6 miles) of ice could provide such a heat source. This result suggests that Mars' magmatism may have been active lately if the interpretation of the observations in liquid water was correct.
The results of the study are tied to the results of a previous work from last year, which provided evidence for a large underground liquid water lake that currently exists under the South Polar ice cap. The new study says that for the existence of such a lake, a heat source must be located deep below the surface – basically a recent magmatic activity within the last hundred thousand years. This is very topical from a geological point of view, and such heat could still be present today. Michael Sori, a research associate at the University of Arizona's Lunar and Planetary Laboratory (LPL) and co-author of the new paper, acknowledges that the new paper will give rise to some debate:
Different people may do this and we are really looking forward to seeing how the community reacts.
The big question is, of course, what this can mean for the search for life. If there is a source of heat in both liquid water and it would increase the chances of subsurface life, albeit probably only microbial. According to Ali Bramson, a postdoctoral fellow in the LPL, and co-author of the new article:
We believe that life, if there is life, is likely to be protected from radiation in the underground. 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 provide a more favorable environment for liquid water and thus perhaps for life.
A liquid lake under the south polar ice would not be surprising, since it also exists under the polar ice caps of the earth. However, scientists are not sure how they would stay liquid on Mars, as the planet is generally much colder than the Earth. As Sori noted:
We thought there was a lot of room to find out whether [the liquid water] is real, what kind of environment you would ever need to melt the ice, what temperatures you would need and what kind of geological process would you need? Because under normal conditions, it should be too cold.
So, if the water is really there, as announced last year, what does it hold liquid? The research team for the new paper carried out modeling experiments on Mars' subsoil – in particular, to check whether salts alone are sufficient. They concluded that salts alone would probably not be able to sufficiently increase the temperature at the base of the ice cap, and that additional heat would be required.
Where would this heat come from? The most plausible source would be volcanic activity underground – a magma chamber under the ice cap. The team estimated that about 300,000 years ago, magma rose from deep below the surface but did not reach the surface but remained in the chamber. The heat of the chamber melted the bottom of the ice cap and formed the lake. Above all, this heat would still have to be made available today not just hundreds of thousands of years ago. As Bramson stated:
This would mean that there is still active magma chamber formation inside Mars today, and that it is not just a cold, dead inside place.
The new release will help scientists better understand how the water in the subterranean lake got there (if that was confirmed) and how it can stay in place. According to Jack Holt, a professor at the LPL, fluent:
Me guess, it was a great idea to do that kind of modeling and analysis because you have to explain the water when it's there, and that's why it's really a critical part of the puzzle. The original paper just let it hang. It could be water there, but you have to explain it, and these people have said really well what is needed and that salt is not enough. Conclusion: A new study states that volcanic activity could still exist underground on Mars, which would help explain the results of a previous study showing a large subterranean lake under the ice at the south pole of Mars. Both findings could have a significant impact on the search for life on Mars.
Source: Water on Mars with a grain of salt: Anomalies of basal ice melt on today's South Pole are required today
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