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Mars' polar ice caps, initially identified in the 19th Century, have puzzled researchers due to their apparent lack of movement. Observations from Mariner 9 in 1971 sparked a decades-long debate about whether these ice caps were flowing. While Earth-like polar ice flow was expected, no clear evidence of movement has been found. A new study led by Planetary Science Institute Senior Scientist Isaa by Staff Writers
Los Angeles CA (SPX) Jun 07, 2024
Mars' polar ice caps, initially identified in the 19th Century, have puzzled researchers due to their apparent lack of movement. Observations from Mariner 9 in 1971 sparked a decades-long debate about whether these ice caps were flowing. While Earth-like polar ice flow was expected, no clear evidence of movement has been found. A new study led by Planetary Science Institute Senior Scientist Isaac Smith proposes that varying layers within the ice may be preventing its flow.
High-resolution images show that the Martian polar ice caps are about 2-3 km thick and extend over 1000 km across the poles, primarily composed of water ice. The terrain beneath the ice includes steep slopes and cliffs, where researchers expected ice flow at speeds up to 1m per year or at least 10 cm per year. Such movement would be detectable with modern imaging, but no signs of flow, such as moraines, depressions, or warped layers, have been observed.
Isaac Smith commented, "So, the question is, why is the ice moving more slowly than predicted, and how slow is it? We have an upper limit, so let"s test some hypotheses. In my paper, I looked at four hypotheses to see if they could slow down the ice."
In the journal Icarus, Smith's paper, "A hypothesis for undetectable flow at the polar layered deposits of Mars," explores four scenarios: 1) the ice is too cold, 2) impurities slow it down, 3) a homogeneous mixture of material slows the flow, and 4) the ice is layered in a way that slows it significantly. The first three scenarios predicted observable movement, but the layered landscape model explained the immobile ice.
Smith explained, "The layers are similar to making smores or an Oreo cookie - stiff layers with soft layers in the middle. If you stack enough oreos on top of each other and press, there will be some flow, but not nearly as much as if you had a mixture of oreo crumbles. The layer model can slow things down by several orders of magnitude - enough to match the observed motions (or lack thereof)."
Understanding the dynamics of Martian ice helps researchers learn about glacier diversity in the solar system. While Mars may seem Earth-like, its unique climate over the past billion years has created distinct features.
Smith added, "Researchers, as far back as Percival Lowell have been considering Mars polar caps. Lowell even considered flowing ice and canals to help people living on Mars. We need to understand the basic physical principles before we can say much more about what is happening on other planets. This is pretty esoteric, very few people get into ice sheet dynamics on other planets, but many more people care about the history of ice on Mars. Without the proper context, we can be misguided for decades. Getting it right, means knowing which processes are active and which are not. I think this paper gets us a lot closer to understanding why the ice on Mars behaves in the non-moving way it does."
Research Report:A hypothesis for undetectable flow at the polar layered deposits of Mars
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