Best region for life on Mars was far below surface

December 02, 2020

The most habitable region for life on Mars would have been up to several miles below its surface, likely due to subsurface melting of thick ice sheets fueled by geothermal heat, a Rutgers-led study concludes.

The study, Science Advances, may help resolve what's known as the faint young sun paradox - a lingering key question in Mars science.

"Even if 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 wet Mars," said lead author

Our sun is a massive nuclear fusion reactor that generates energy by fusing hydrogen into helium. Over time, the sun has gradually brightened and warmed the surface of planets in our solar system. About 4 billion years ago, the sun was much fainter so the climate of early Mars should have been freezing. However, the surface of Mars has many geological indicators, such as ancient riverbeds, and chemical indicators, such as water-related minerals, that suggest the red planet had abundant liquid water about 4.1 billion to 3.7 billion years ago (the Noachian era). This apparent contradiction between the geological record and climate models is the faint young sun paradox.

On rocky planets like Mars, Earth, Venus and Mercury, heat-producing elements like uranium, thorium and potassium generate heat via radioactive decay. In such a scenario, liquid water can be generated through melting at the bottom of thick ice sheets, even if the sun was fainter than now. On Earth, for example, geothermal heat forms subglacial lakes in areas of the West Antarctic ice sheet, Greenland and the Canadian Arctic. It's likely that similar melting may help explain the presence of liquid water on cold, freezing Mars 4 billion years ago.

The scientists examined various Mars datasets to see if heating via geothermal heat would have been possible in the Noachian era. They showed that the conditions needed for subsurface melting would have been ubiquitous on ancient Mars. Even if Mars had a warm and wet climate 4 billion years ago, with the loss of the magnetic field, atmospheric thinning and subsequent drop in global temperatures over time, liquid water may have been stable only 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 (heating) activity and rock-water reactions," Ojha said. "So, the subsurface may represent the longest-lived habitable environment on Mars."


Scientists at Dartmouth College, Louisiana State University and the Planetary Science Institute contributed to the study.
-end-


Rutgers University

Related Mars Articles from Brightsurf:

Water on ancient Mars
A meteorite that originated on Mars billions of years ago reveals details of ancient impact events on the red planet.

Surprise on Mars
NASA's InSight mission provides data from the surface of Mars.

Going nuclear on the moon and Mars
It might sound like science fiction, but scientists are preparing to build colonies on the moon and, eventually, Mars.

Mars: Where mud flows like lava
An international research team including recreated martian conditions in a low-pressure chamber to observe the flow of mud.

What's Mars made of?
Earth-based experiments on iron-sulfur alloys thought to comprise the core of Mars reveal details about the planet's seismic properties for the first time.

The seismicity of Mars
Fifteen months after the successful landing of the NASA InSight mission on Mars, first scientific analyses of ETH Zurich researchers and their partners reveal that the planet is seismically active.

Journey to the center of Mars
While InSight's seismometer has been patiently waiting for the next big marsquake to illuminate its interior and define its crust-mantle-core structure, two scientists, have built a new compositional model for Mars.

Getting mac and cheese to Mars
Washington State University scientists have developed a way to triple the shelf life of ready-to-eat macaroni and cheese, a development that could have benefits for everything from space travel to military use.

Life on Mars?
Researchers from Hungary have discovered embedded organic material in a Martian meteorite found in the late 1970s.

New evidence of deep groundwater on Mars
Researchers at the USC Arid Climate and Water Research Center (AWARE) have published a study that suggests deep groundwater could still be active on Mars and could originate surface streams in some near-equatorial areas on Mars.

Read More: Mars News and Mars Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.