Mars may now be a planet desiccated by icy conditions, but once upon a time, it was supposed to have been (almost) another Earth, with flowing water that froze into massive mountains of ice.
Because glaciers and ice sheets up Earth they tend to slip and slide, creep across the earth, and carve out sharp geophysical features such as linear grooves, ridges, and inverted hills. Scientists previously believed that the glaciers on Mars remained frozen in time due to the lack of similar features on the Red Planet. Planetologist Anna Grau Galofre of the Laboratoire de Planétologie et Géosciences at the University of Nantes in France led a study (opens in new tab) found glaciers on Mars are moving — they just happen to be extremely slow.
“On Earth, this glacial movement has created landscapes in northern Europe and North America,” wrote Grau Galofre. “Mars does not have such large-scale glacial erosion even in areas with other signs of extensive glaciation.”
Related: These dry ice glaciers on Mars are moving at its south pole
In contrast, Martian landforms created by melting and moving glaciers are mostly ridges and valleys with shallow, undulating channels. Scientists had previously assumed that Martian glaciers froze directly into the ground when they formed, as Mars lacks Earth’s most dramatic glacial terrain. To find out if the ice actually remained, Grau Galofre and her team created models of identical ice sheets, subjecting one to conditions on Earth and another to conditions on Mars.
Scientists have discovered that they are of Earth gravity which causes meltwater to pool under a glacier instead of draining away immediately. The concentrated water makes the glacier move faster, kind of like the hydroplaning that happens when cars end up skidding uncontrollably because of a layer of water between their tires and the road. However, on Mars, the lower gravity means drainage occurs much faster, Grau Galofre and her colleagues found that not as much water accumulates under the ice, so Martian glaciers cannot travel as fast or as far .
Some glaciers on Mars may have had a helping hand from below. The research team hypothesized that to push the glaciers faster, there would have to be enough stress to compensate for the weaker gravity. Creep deformation (opens in new tab) is a phenomenon that occurs when both temperature and pressure from the weight of heavy ice above, known as overload pressure, apply enough pressure to the ice that it begins to deform. On Earth, creep deformation is not as widespread as ice sliding resulting from melting glaciers that pool under that ice. Formations on Mars as parts of it Silver Basin in his southern hemisphere were probably affected by this extra speed.
It turns out that glaciers that behave much like what researchers suggest happens on Mars do occur on Earth. In the far north of the Arctic, the ground beneath some glaciers shows almost none of the scours and grooves that mark places where enough meltwater keeps the ice moving and scraping new features in its wake.
It’s possible, Grau Galofre believes, that the glaciers could once have been a refuge for primordial Martian life, if it existed, since they would have doubled as a near-endless source of water and a shield from harsh radiation. Earth creatures like black ice worms they thrive in the glacier ice.
Perhaps something long frozen is waiting to be discovered deep within a glacier on Mars.
The research is described in a paper was published in July in the journal Geophysical Research Letters.
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