beecee Posted May 25, 2019 Posted May 25, 2019 (edited) https://phys.org/news/2019-05-massive-martian-ice-discovery-window.html Massive Martian ice discovery opens a window into red planet's history: Newly discovered layers of ice buried a mile beneath Mars' north pole are the remnants of ancient polar ice sheets and could be one of the largest water reservoirs on the planet, according to scientists at The University of Texas at Austin and the University of Arizona. The team made the discovery using measurements gathered by the Shallow Radar (SHARAD) on NASA's Mars Reconnaissance Orbiter (MRO). SHARAD emits radar waves that can penetrate up to a mile and a half beneath the surface of Mars. The findings, published May 22 in Geophysical Research Letters, are important because the layers of ice are a record of past climate on Mars in much the same way that tree rings are a record of past climate on Earth. Studying the geometry and composition of these layers could tell scientists whether climate conditions were previously favorable for life, researchers said. The team found layers of sand and ice that were as much as 90% water in some places. If melted, the newly discovered polar ice would be equivalent to a global layer of water around Mars at least 1.5 meters (5 feet) deep. more at link.... the paper: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL082114 Buried ice and sand caps at the north pole of Mars: revealing a record of climate change in the cavi unit with SHARAD: Abstract: The cavi unit at the north pole of Mars is a deposit of aeolian sand and water ice underlying the Late Amazonian north polar layered deposits (NPLD). Its strata of Middle to Late Amazonian age record wind patterns and past climate. The Mars Reconnaissance Orbiter Shallow Radar (SHARAD) reveals extensive internal and basal layering within the cavi unit, allowing us to determine its general structure and relative permittivity. Assuming a basalt composition for the sand (ε’=8.8), results indicate that cavi contains an average ice fraction between 62% in Olympia Planum and 88% in its northern reaches beneath the NPLD, and thus represents one of the largest water reservoirs on the planet. Internal reflectors indicate vertical variability in composition, likely in the form of alternating ice and sand layers. The ice layers may be remnants of former polar caps, and thus represent a unique record of climate cycles predating the NPLD. Plain language summary: The north polar region of Mars includes the so‐called cavi unit, a deposit of water ice and sand hundreds of million years old that lies beneath the current ice cap. The Shallow Radar on Mars Reconnaissance Orbiter can image through the cavi unit deposits, revealing their internal structure and composition. We find that these deposits are very rich in ice, which lies in horizontal slabs alternated with sand. The occurrence and volume of ice slabs increases towards the north pole. This ice may be the leftover of former ice caps that diminished during warm periods, and therefore represents an important record of past martian climate. The large volume of ice preserved within the cavi unit represents one of the largest water reservoirs on the planet. Edited May 25, 2019 by beecee
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