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A letter written by Oliver White, a researcher at the SETI Institute, was published by Nature Astronomy today. The co-authors were researchers Jeff Moore, Tanguy Bertrand and Kimberly Ennico from NASA's Ames Research Center in Silicon Valley.
The letter "Washed and Fluted Terrains on Pluto, Evidence of Ancient Glaciation" focuses on these distinctive landscapes that border Sputnik Planitia's vast, flat, glacial plains along its northwestern margin (Figure 1) and which are among the most enigmatic forms ever seen in Pluto. . These lands consist of parallel to sub-parallel ridges with a remarkably consistent ENE-WSW orientation, a configuration that does not easily point to a similar earthly or planetary process or landform.
Dr. White's research aims to use mapping and analysis of morphometry (the process of measuring the shape and external dimensions of reliefs) and the distribution of ridges to determine their origin. and to understand their meaning in the overall geological history of Pluto. . The work used imagery data returned by NASA's New Horizons spacecraft, which flew over Pluto in 2015, as well as topographic maps generated from these data.
The ridges of the washboard and grooves are defined primarily by their topographic context: the ridges of the washboard are level in valley bottoms, basins and uplands, while fluted ridges are visible on the spurs, the massifs (or groups of compact mountains) and the valleys.
The washboard and the fluted ground are seen closely in Figure 2, in which the lighting is from the top. They occur at the Sputnik Planitia perimeter, where the altitudes and slopes leading to the surrounding highlands are the lowest, as well as a major tectonic system coinciding with the periphery of Sputnik Planitia.
The low altitude of the area makes it a natural setting for the past cover by the Nitrogen Glaciers, as indicated by modeling the volatile behavior on Pluto made by Dr. Bertrand at Ames. By comparing the texture of the washboard and flutes with the parallel chains of elongated troughs (surface-formed depressions where ice is transformed directly into gas) observed in the south of Sputnik Planitia, the ridges are interpreted as representing debris of ice released by the tectonism of the underlying crust. .
This ice-water debris floated in the denser and sharper ice-ice, supposedly covering this area and collecting elongated pits on the ground. After the nitrogen ice was removed by sublimation, the debris was left in the form of aligned ridges, imitating the sublimation texture – the ridges of the washboard were deposited on flat ground and the ridges were fluted have been deposited on steeper slopes.
The age estimates of the crater surface indicate that the washboard ridges and grooves were deposited early in the Pluto's history, after the formation of the Sputnik basin by a huge impact there about 4 billion years ago. As a gigantic cold trap, it is in this basin that surface nitrogen ice across Pluto has migrated for tens of millions of years, causing recession of upland nitrogen glaciers. such as those currently occupied by the washboard and fluted ground.
The precise mechanism that has lengthened the sublimation dips and defined their remarkably consistent orientation, regardless of their latitude or location relative to Sputnik Planitia, is difficult to pin down, but remains consistent with a global process.
One constraint lies in the fact that true polar wandering solutions for Pluto (provided by co-author, James Keane of Caltech) indicate that the peaks can never have all been oriented from the NS at a time of time. History of Pluto. This suggests a cause of alignment that is not exogenous (that is, the orientation is probably not solely governed by solar illumination , which would result in the alignment of all sublimation hollows on NS).
Dr. White summarizes the results as follows: "These lands constitute an entirely new category of Pluto-specific glacial landforms, and provide a geological evidence of the largest glaciation of ice-freezing with nitrogen at its sites. The dense spacing of ridges allows us to accurately map the past cover of the glaciation that deposited them, which spanned at least 70,000 km2 of the Pluto Highlands (larger than the state of West Virginia). "
Research Report: "Washable and Fluted Wastes on Pluto as Evidence of Ancient Glaciation", Oliver L. White et al., November 12, 2018, Nature Astronomy
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The SwRI team makes breakthroughs in the study of the Pluto Orbiter mission
San Antonio TX (SPX) Oct 25, 2018
A team from the Southwest Research Institute using internal research funds has made several discoveries that expand the scope and value of a future Pluto orbiter mission. The discoveries define a fuel-saving orbital circuit and demonstrate that an orbiter can continue exploration in the Kuiper Belt after inspecting Pluto. These and other results of the study will be presented this week at a workshop on the future exploration of Pluto and the Kuiper Belt in the Planetary Science Division of the American Astronomical Society … to find out more
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