SETI Institute scientist Oliver White, et al, are working out why Pluto has ridges in an article (paywall) for Nature Astronomy. Here’s the abstract:
Image Source: Phys.org
Distinctive landscapes termed ‘washboard’ and ‘fluted’ terrains1,2, which border the N2 ice plains of Sputnik Planitia along its northwest margin, are among the most enigmatic landforms yet seen on Pluto. These terrains consist of parallel to sub-parallel ridges that display a remarkably consistent east-northeast–west-southwest orientation—a configuration that does not readily point to a simple analogous terrestrial or planetary process or landform. Here, we report on mapping and analysis of their morphometry and distribution as a means to determine their origin. Based on their occurrence in generally low-elevation, low-relief settings adjacent to Sputnik Planitia that coincide with a major tectonic system, and through comparison with fields of sublimation pits seen in southern Sputnik Planitia, we conclude that washboard and fluted terrains represent crustal debris that were buoyant in pitted glacial N2 ice that formerly covered this area, and which were deposited after the N2 ice receded via sublimation. Crater surface age estimates indicate that this N2 ice glaciation formed and disappeared early in Pluto’s history, soon after formation of the Sputnik Planitia basin. These terrains constitute an entirely new category of glacial landform.
Besides the fact that it’s just cool to imagine a glacial feature created by N2, I’m intrigued by their last statement that this is a new category of glacial landform. Their entire abstract reminds me of descriptions of standard H2O glaciers that have left boulders (similar to “crustal debris”) sitting around various parts of the United States, after all. What’s the difference? Just the sublimation aspect of their formation?
Phys.org has more here.
