Convection in a volatile nitrogen-ice-rich layer drives Pluto's geological vigor
Abstract
The vast, deep, volatile-ice-filled basin informally named Sputnik Planum is central to Pluto's geological activity[1,2]. Composed of molecular nitrogen, methane, and carbon monoxide ices[3], but dominated by N2-ice, this ice layer is organized into cells or polygons, typically ~10-40 km across, that resemble the surface manifestation of solid state convection[1,2]. Here we report, based on available rheological measurements[4], that solid layers of N2 ice approximately greater than 1 km thick should convect for estimated present-day heat flow conditions on Pluto. More importantly, we show numerically that convective overturn in a several-km-thick layer of solid nitrogen can explain the great lateral width of the cells. The temperature dependence of N2-ice viscosity implies that the SP ice layer convects in the so-called sluggish lid regime[5], a unique convective mode heretofore not definitively observed in the Solar System. Average surface horizontal velocities of a few cm/yr imply surface transport or renewal times of ~500,000 years, well under the 10 Myr upper limit crater retention age for Sputnik Planum[2]. Similar convective surface renewal may also occur on other dwarf planets in the Kuiper belt, which may help explain the high albedos of some of them.
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@article{arxiv.1903.05571,
title = {Convection in a volatile nitrogen-ice-rich layer drives Pluto's geological vigor},
author = {William B. McKinnon and Francis Nimmo and Teresa Wong and Paul M. Schenk and Oliver L. White and J. H. Roberts and J. M. Moore and J. R. Spencer and A. D. Howard and O. M. Umurhan and S. A. Stern and H. A. Weaver and C. B. Olkin and L. A. Young and K. E. Smith and R. Beyer and R. P. Binzel and M. Buie and B. Buratti and A. Cheng and D. Cruikshank and C. Dalle Ore and A. Earle and R. Gladstone and W. Grundy and T. Lauer and I. Linscott and J. Parker and S. Porter and H. Reitsema and D. Reuter and S. Robbins and M. Showalter and K. Singer and D. Strobel and M. Summers and L. Tyler and H. Weaver and M. Banks and O. Barnouin and V. Bray and B. Carcich and A. Chaikin and C. Chavez and C. Conrad and D. Hamilton and C. Howett and J. Hofgartner and J. Kammer and C. Lisse and A. Marcotte and A. Parker and K. Retherford and M. Saina and K. Runyon and R. Schindhelm and J. Stansberry and A. Steffl and T. Stryk and . H. Throop and C. Tsang and A. Verbiscer and H. Winters and A. Zangari},
journal= {arXiv preprint arXiv:1903.05571},
year = {2021}
}