A study published last year in the journal Science suggested that liquid water is present beneath the ice sheet at the south pole of Mars. Now, a new study in the magazine AGU. Geophysical research letters He argues that there must be an underground source of heat for liquid water to exist beneath the polar ice cap.
The new research does not take sides if liquid water exists. Instead, the authors suggest that recent magmatic activity, the formation of a magma chamber in the last hundreds of thousands of years, must have occurred below the surface of Mars so that there is enough heat to produce liquid water below the kilometer and medium. thick layer of ice. On the other hand, the authors of the study argue that if there was no recent magmatic activity below the surface of Mars, then there is probably no liquid water beneath the ice sheet.
"Different people can go different ways with this, and we are really interested in seeing how the community reacts," said Michael Sori, associate scientist at the University of Arizona Lunar and Planetary Laboratory and a co-leader. Author of the new article .
The potential presence of the recent underground magmatic activity on Mars lends weight to the idea that Mars is an active planet, geologically speaking. That fact could give scientists a better understanding of how planets evolve over time.
The new study is intended to promote debate about the possibility of liquid water on Mars. The presence of liquid water on the Red Planet has implications for the possibility of finding 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 is likely that it should be protected in the subsoil of radiation," said Ali Bramson, a postdoctoral researcher at the Lunar and Planetary Laboratory at the University of Arizona and co-principal author of The New Paper. "If magmatic processes are still active today, they may have been more common in the recent past and could provide a more widespread basal melt, which could provide a more favorable environment for liquid water and, therefore, perhaps life." .
Examining the environment
Mars has two giant ice sheets at its poles, both a couple of kilometers thick. On Earth, it is common for there to be liquid water beneath the thick layers of ice, and the heat of the planet causes the ice to melt where it meets the earth's crust.
In an article published last year in Science, scientists said they detected a similar phenomenon on Mars. They claimed that the radar observations detected evidence of liquid water at the base of the ice sheet at the south pole of Mars. However, the Science study did not address how liquid water could have gotten there.
Mars is much colder than Earth, so it was not clear what kind of environment would be needed to melt the ice at the base of the ice sheet. Although previous research has examined whether liquid water could exist at the base of the Martian ice caps, no one had examined the specific location where the Science study claimed to have detected water.
"We thought there was a lot of space to find out if [the liquid water] It's real, what kind of environment would you need to melt the ice in the first place, what kind of temperatures would you need, what kind of geological process would you need? Because under normal conditions, it should be too cold, "said Sori.
Looking for the heat
The authors of the new study first assumed that the detection of liquid water beneath the ice sheet was correct and then worked to determine what parameters were necessary for water to exist. They did a physical modeling of Mars to understand the amount of heat that comes out from inside the planet and if there could be enough salt at the base of the ice sheet to melt the ice. Salt significantly reduces the melting point of ice, so it was thought that salt could have caused it to melt at the base of the ice sheet.
The model showed that the salt alone would not raise the temperature high enough to melt the ice. Instead, the authors propose that it is necessary that there be additional heat coming from the interior of Mars.
A plausible heat source would be the volcanic activity in the subsoil of the planet. The authors of the study argue that magma from the deep interior of Mars rose to the surface of the planet about 300,000 years ago. It did not break the surface, like a volcanic eruption, but instead grouped into a magma chamber below the surface. When the magma chamber cooled, it released heat that melted the ice at the base of the ice sheet. The magma chamber still provides heat to the ice sheet to generate liquid water at present.
The idea of volcanic activity on Mars is not new: there is a lot of evidence of volcanism on the surface of the planet. But most of the volcanic features on Mars are millions of years old, leading scientists to believe that volcanic activity below and above the surface of the planet stopped a long time ago.
The new study, however, proposes that there may have been more recent underground volcanic activity. And, if there was volcanic activity hundreds of thousands of years ago, there is a possibility that it is happening today, according to the authors of the study.
"This would imply that there is still an active magma chamber formation inside Mars today, and it's not just a cold and dead place," Bramson said.
Jack Holt, a professor at the Lunar and Planetary Laboratory at the University of Arizona, said the question of how water could exist beneath the ice sheet at the south pole occurred immediately after the Science paper was published, and The new article adds a significant restriction on the possibility of water there. He said that the debate in the planetary scientific community will probably increase the finding and will indicate that more research is needed to evaluate it.
"I think it was a great idea to do this kind of modeling and analysis because he has to explain the water, if it's there, and that's why it's really a critical piece of the puzzle," said Holt, who was not involved in the new research, but He spoke with the authors of the study before presenting the document. "The original paper just left it hanging in. There could be water there, but you have to explain it, and these guys did a very good job of saying what is needed and that salt is not enough."
Stock Photo: Radar footprints above the buried Mars lake
"Water on Mars, with a grain of salt: local heat anomalies are required today for the basal melting of ice in the south pole" Geophysical research letters (2019). agupubs.onlinelibrary.wiley.co … 10.1029 / 2018GL080985