Mars did Have Moving Glaciers, but They Behaved Differently in the Planet's Lower Gravity

Glaciers have advanced and retreated throughout our geological history due to shifts in our climate. There are carved features on the surface of the glaciers. The glaciers on the surface of Mars were not present in the distant past. According to new research by a team of U.S. and French planetary scientists, the glaciers on Mars did not move as quickly as the ones on Earth.

The research was conducted by a team of geologists and planetary scientists from the School of Earth and Space Exploration at Arizona State University. Anna Grau Galofre, an Exploration Fellow with the SESE, was the leader of the study that was conducted at the time she was a PhD student. The study titled " Valley Networks and the Record of Glaciation on Ancient Mars" was published in the Geophysical Research Letters.

A glacier is a large, perennial accumulate of ice, snow, rock, and water that starts on land and moves downslope under the influence of its own weight and gravity, according to the US Geological Survey. meltwater gathering below the ice sheet lubricating its passage down across the landscape is the key word here. Glaciers have retreated and left boulders and debris in their wake on Earth.

Galofre and her colleagues modeled how Martian gravity would affect the feedback between how fast an ice sheet moves and how much water goes into it. Under-ice channels that would likely persist over time would be caused by faster water drainage. Ice sheets on Mars likely moved and eroded the ground under them at an extremely slow rate compared to what happens on Earth. Scientists have found evidence that suggests there was activity on Mars in the past.

The ridges are made of sand and gravel and could be the result of subglacial channels. In a recent AGUnews press release, said Galofre.

“Ice is incredibly non-linear. The feedbacks relating glacial motion, glacial drainage, and glacial erosion would result in fundamentally different landscapes related to the presence of water under former ice sheets on Earth and Mars. Whereas on Earth you would get drumlins, lineations, scouring marks and moraines, on Mars you would tend to get channels and esker ridges under an ice sheet of exactly the same characteristics.”

Grau Galofre and her colleagues modeled the dynamics of two ice sheets on Earth and Mars in order to determine if Mars experienced glaciers in the past. They adapted the physical framework and ice flow dynamics to Mars. They learned how subglacial drainage would evolve on Mars, how it would affect the glaciers, and how it would cause erosion.

The findings show that glaciers on Earth are not as efficient as glaciers on Mars. This would prevent lubrication at the base of the ice sheets which would lead to faster sliding rates. Their study shows that lineated landforms on Earth would not have been developed on Mars. Said GrauGalofre.

“Going from an early Mars with presence of surface liquid water, extensive ice sheets and volcanism into the global cryosphere that Mars currently is, the interaction between ice masses and basal water must have occurred at some point. It is just very hard to believe that throughout 4 billion years of planetary history, Mars never developed the conditions to grow ice sheets with presence of subglacial water, since it is a planet with extensive water inventory, large topographic variations, presence of both liquid and frozen water, volcanism, [and is] situated further from the Sun than Earth.”

The work has implications for the possibility of life on Mars and whether that life could survive the transition to a global cryosphere we see today. The authors say that an ice sheet could provide a steady water supply, protection, and stability to any subglacial bodies of water where life could have arisen. In the absence of a magnetic field, they would protect against solar and Cosmic Radiation.

These findings are part of a growing body of evidence that supports the existence of life on Mars. It shows that missions like Perseverance, which will be launched in the near future, are looking in the right place. When Mars was warm and wet, there were life forms that emerged from the glaciers. As the planet became colder and desiccated, it might have continued.

It is possible that as this transition progressed and much of Mars' surface water retreated underground, there could be life on the surface. Future Mars missions could be the ones that find evidence of life on the red planet.

Further reading: AGU news.