Penitentes as the origin of the bladed terrain of Tartarus Dorsa, Pluto

Abstract

Penitentes are ablative features observed in snow and ice that, on Earth, are characterized by regular cm to tens of cm spaced bowl-shaped depressions whose edges grade into tall spires up to several meters tall (Nichols et al. 1939, Lliboutry et al. 1954, Claudin et al. 2015). While penitentes have been suggested as an explanation for anomalous radar data on Europa (Hobley et al. 2013), hitherto no penitentes have been identified conclusively on other planetary bodies. Regular ridges with spacing of 3000 m to 5000 m and a depth of $\sim 500$ m with morphologies that resemble penitentes (Fig. 1) have been observed by the New Horizons spacecraft (Moore et al. 2016, Stern et al. 2015, Gladstone et al. 2016, Moore et al. 2017) in the Tartarus Dorsa (TD) region of Pluto (approximately 220-250${}^{\circ }$ E, 0-20${}^{\circ }$ N). Here we report simulations, based upon a recent model (Claudinet al. 2015) adapted to conditions on Pluto (Gladstone et al. 2016, Toigo et al. 2015), that reproduce both the tri-modal orientation and the spacing of these features by deepening penitentes. These penitentes deepen by of order 1 cm per orbital cycle in the present era and grow only during periods of relatively high atmospheric pressure, suggesting a formation timescale of several tens of millions of years, consistent with cratering ages and the current atmospheric loss rate of methane. This time scale, in turn, implies that the penitentes formed from initial topographic variations of no more than a few 10s of meters, consistent with Pluto's youngest terrains.

arXiv comment12 pages, 5 figures, 1 table, authors' accepted version of the manuscript submitted as a letter to Nature and published 12th Jan 2017. V2 uploaded to correct a typographical error

References in corpus (6)

• The Pluto system: Initial results from its exploration by New Horizons
• The Geology of Pluto and Charon Through the Eyes of New Horizons
• The Atmosphere of Pluto as Observed by New Horizons
• Convection in a volatile nitrogen-ice-rich layer drives Pluto's geological vigor
• Controlled Irradiative Formation of Penitentes
• Physical processes causing the formation of penitentes

Cited by in corpus (9)

• The Pluto System After New Horizons
• Pluto's Haze as a Surface Material
• The CH4 cycles on Pluto over seasonal and astronomical timescales
• Large-scale cryovolcanic resurfacing on Pluto
• Low temperature formation of pyridine and (iso)quinoline via neutral neutral reactions
• Twin Worlds, Divergent Fates: How Obliquity has differently shaped Pluto's and Triton's landscapes and climates
• Buoyancy driven dissolution of inclined blocks: Erosion rate and pattern formation
• Investigating the extent of bladed terrain on Pluto via photometric surface roughness
• Formation of spiky structures in high-altitude snow patches: penitente tilting