2017/05/31 by Asmin V. Pathare, A. V. Pathare, W. C. Feldman +5 · 59 citations
Physics and Astronomy · #Astro and Planetary Science #Astrobiology #Atmosphere of Mars #Atmospheric sciences #Environmental science #Geology #Geometry #Hydrogen #Mars Exploration Program #Martian #Meteorology #Physics #Planetary Science and Exploration #Space Science and Extraterrestrial Life #Surface (topology) #astro-ph.EP
paper · pdf · doi:10.1016/j.icarus.2017.09.031
published in Icarus 301, 97-116 (Elsevier BV) · 89 pages, 33 figures, revision submitted to Icarus
arxiv created 2017/08/25 · openalex publication_date 2017/10/13 · arxiv updated 2017/12/05 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present improved Mars Odyssey Neutron Spectrometer (MONS) maps of near-surface Water-Equivalent Hydrogen (WEH) on Mars that have intriguing implications for the global distribution of "excess" ice, which occurs when the mass fraction of water ice exceeds the threshold amount needed to saturate the pore volume in normal soils. We have refined the crossover technique of Feldman et al. (2011) by using spatial deconvolution and Gaussian weighting to create the first globally self-consistent map of WEH. At low latitudes, our new maps indicate that WEH exceeds 15% in several near-equatorial regions, such as Arabia Terra, which has important implications for the types of hydrated minerals present at low latitudes. At high latitudes, we demonstrate that the disparate MONS and Phoenix Robotic Arm (RA) observations of near surface WEH can be reconciled by a three-layer model incorporating dry soil over fully saturated pore ice over pure excess ice: such a three-layer model can also potentially explain the strong anticorrelation of subsurface ice content and ice table depth observed at high latitudes. At moderate latitudes, we show that the distribution of recently formed impact craters is also consistent with our latest MONS results, as both the shallowest ice-exposing crater and deepest non-ice-exposing crater at each impact site are in good agreement with our predictions of near-surface WEH. Overall, we find that our new mapping is consistent with the widespread presence at mid-to-high Martian latitudes of recently deposited shallow excess ice reservoirs that are not yet in equilibrium with the atmosphere.