[ad_1]
A vertically exaggerated, false color view of a large water-sculpted canal on Mars called Dao Vallis. Credit: ESA / DLR / FU Berlin, CC BY-SA 3.0 IGO. 3D rendered and colored by Lujendra Ojha
A new study sheds light on underground ice melting often billions of years ago.
The most habitable region for life Mars it would have been up to several miles below its surface, likely due to the underground melting of thick sheets of ice fed by geothermal heat, concludes a study by Rutgers.
The study, published in the journal Advances in science, can help solve what’s known as the feeble young sun paradox, a persistent key question in the science of Mars.
“Even though greenhouse gases like carbon dioxide and water vapor are pumped into the early Martian atmosphere in computer simulations, climate models still struggle to support a long-term warm and humid Mars,” said lead author Lujendra. Ojha, assistant professor of the Department. of Earth and Planetary Sciences at the School of Arts and Sciences of Rutgers University – New Brunswick. “My co-authors and I propose that the feeble young sun paradox can be reconciled, at least in part, if Mars previously had high geothermal heat.”
Our sun is a huge nuclear fusion reactor that generates energy by fusing hydrogen into helium. Over time, the sun has gradually illuminated and heated the surface of the planets in our solar system. About 4 billion years ago, the sun was much weaker, so the climate of early Mars should have been freezing. However, the surface of Mars has many geological markers, such as ancient river beds, and chemical markers, such as water-related minerals, which suggest that the red planet had abundant liquid water of approximately 4.1 billion to 3.7 billion. billions of years ago (the Noachian era). This apparent contradiction between the geological record and climate models is the feeble paradox of the young sun.
On rocky planets like Mars, Earth, Venus and Mercury, heat-producing elements such as uranium, thorium and potassium generate heat through radioactive decay. In such a scenario, liquid water can be generated by melting at the bottom of thick ice sheets, even if the sun was weaker than it is now. On Earth, for example, geothermal heat forms subglacial lakes in the areas of the West Antarctic ice sheet, Greenland and the Canadian Arctic. A similar melting is likely to help explain the presence of liquid water on cold, freezing Mars 4 billion years ago.
Scientists looked at various data sets on Mars to see if warming by geothermal heat would have been possible in the Noachian era. They showed that the conditions necessary for the melting of the subsoil would be omnipresent on ancient Mars. Even if Mars had a hot and humid climate 4 billion years ago, with the loss of the magnetic field, atmospheric thinning and the consequent decline in global temperatures over time, liquid water could only have been stable at great depths. Therefore, life, if it ever originated on Mars, may have followed liquid water to progressively greater depths.
“At such depths, life could have been sustained by hydrothermal (warming) activity and water-rock reactions,” Ojha said. “So, the subsoil could represent the longest lived habitable environment on Mars.”
NASAThe Mars InSight spacecraft landed in 2018 and could allow scientists to better assess the role of geothermal heat in Mars’ habitability during the Noachian era, according to Ojha.
Reference: “Groundwater Production from Geothermal Warming at Early Mars and Implications for Early Martian Habitability” by Lujendra Ojha, Jacob Buffo, Suniti Karunatillake and Matthew Siegler, 2 December 2020, Advances in science.
DOI: 10.1126 / sciadv.abb1669
Scientists from Dartmouth College, Louisiana State University, and the Planetary Science Institute contributed to the study.
[ad_2]
Source link
