by |
Khaled Younes |
Saturday 17 September 2022 – 06:10 PM
Through time immemorial, climatic shifts on the planet have led to the advance and retreat of glaciers throughout our geological history (known as ice ages and interglacial periods).
The movement of these glaciers has carved features on the surface, including U-shaped valleys, hanging valleys, and fjords. These features are missing on the surface of Mars, leading scientists to conclude that glaciers on its surface were fixed in the distant past.
However, new research by a team of American and French planetary scientists indicates that the glaciers on Mars moved, but more slowly than those on Earth.
The research was conducted by a team of geologists and planetary scientists from the School of Earth and Space Exploration (SESE) at Arizona State University (ASU) and Laboratoire de Planétologie et Géosciences (LPG) at the University of Nantes in France.
The study was led by Anna Grau Gallover, a 2018 exploration fellow from the School of Earth and Space Exploration SESE (currently at LPG) and was a postdoctoral researcher at Arizona State University when it was conducted.
The study, titled “Valley Networks and the Dating of Ice Ages on Ancient Mars,” appeared recently in Geophysical Research Letters.
The effect of gravity on the movement of ice
According to the USGS definition, a glacier is “a large and permanent accumulation of crystalline ice, snow, rock, sediment and glacial aggregate, often here liquid water that arises at the surface and moves downward under the influence of its own weight and gravity.”
The key word here is about the movements caused by meltwater gathering under the ice sheet and this eroding the terrain as it moves. On Earth, glaciers have regularly advanced and retreated for several eons, leaving rocks and debris in their wake and carving “features” into the surface.
To carry out their study, Grau-Glover and colleagues modeled how Mars’ gravity affects how fast the ice sheet moves and how water drains beneath it. Faster draining of water can increase the friction between rock and ice, leaving channels under the ice that are likely to persist over time.
The absence of these U-shaped valleys means that the ice sheets on Mars moved and eroded the ground beneath them at very slow rates compared to what is happening on Earth, according to Russia Today.
geological monuments
However, scientists have found other geological traces that indicate glacial activity on Mars in the past. These include, inter alia, long, narrow, winding ridges of eskers and other features that may be the result of subglacial channels.
To determine whether Mars has experienced glacial activity in the past, Grau and her colleagues modeled the dynamics of two ice sheets on Earth and Mars that have the same thickness and temperature and have the same meltwater availability below them.
They then adapted the physical framework and ice flow dynamics that describe subterranean water drainage in Martian conditions.
From this, they learned how subglacial puncture would develop on Mars, what effects this would have on how quickly glaciers slide across natural terrain, and how much erosion this might cause.
These findings illustrate how glacier ice on Mars can drain meltwater more efficiently than glaciers on Earth. This would largely prevent lubrication at the base of the ice sheets, which would lead to faster slip rates and enhance glacier erosion.
In short, their study showed that landforms on Earth associated with icy activity did not have time to evolve there on Mars.
In addition to explaining why Mars lacks certain icy features, the work also has implications for the possibility of life on Mars and whether that life could survive the transition to the global cryosphere we see today.
An ice sheet can provide a constant supply of water and protect and stabilize any sub-glacial bodies of water where life could have originated. They also protect against solar and cosmic radiation (in the absence of a magnetic field) and provide insulation against extreme temperature changes.
These findings are part of a growing body of evidence that life has existed on Mars and has survived long enough to leave evidence of its existence behind.
These findings may also bolster speculation that life on Mars followed the progression of this transition and that much of Mars’ surface water retreated below the surface.
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