The water content of recurring slope lineae on Mars

Christopher S. Edwards, Sylvain Piqueux

Research output: Contribution to journalArticlepeer-review

48 Scopus citations

Abstract

Observations of recurring slope lineae (RSL) from the High-Resolution Imaging Science Experiment have been interpreted as present-day, seasonally variable liquid water flows; however, orbital spectroscopy has not confirmed the presence of liquid H2O, only hydrated salts. Thermal Emission Imaging System (THEMIS) temperature data and a numerical heat transfer model definitively constrain the amount of water associated with RSL. Surface temperature differences between RSL-bearing and dry RSL-free terrains are consistent with no water associated with RSL and, based on measurement uncertainties, limit the water content of RSL to at most 0.5–3 wt %. In addition, distinct high thermal inertia regolith signatures expected with crust-forming evaporitic salt deposits from cyclical briny water flows are not observed, indicating low water salinity (if any) and/or low enough volumes to prevent their formation. Alternatively, observed salts may be preexisting in soils at low abundances (i.e., near or below detection limits) and largely immobile. These RSL-rich surfaces experience ~100 K diurnal temperature oscillations, possible freeze/thaw cycles and/or complete evaporation on time scales that challenge their habitability potential. The unique surface temperature measurements provided by THEMIS are consistent with a dry RSL hypothesis or at least significantly limit the water content of Martian RSL.

Original languageEnglish (US)
Pages (from-to)8912-8919
Number of pages8
JournalGeophysical Research Letters
Volume43
Issue number17
DOIs
StatePublished - Sep 16 2016

Keywords

  • Mars
  • recurring slope lineae
  • THEMIS
  • thermophysics
  • water budget

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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