Sublimation of terrestrial permafrost and the implications for ice-loss processes on Mars

• Published in: Nature Communications
• Main Authors: Douglas, Thomas A., Mellon, Michael T.
• Format: Text
• Language: English
• Published: Nature Publishing Group UK 2019
• Subjects: Article; Fairbanks; Ice; permafrost; wedge*; Alaska
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6461685/; http://www.ncbi.nlm.nih.gov/pubmed/30979886; https://doi.org/10.1038/s41467-019-09410-8

Sublimation of ice is rate-controlled by vapor transport away from its outer surface and may have generated landforms on Mars. In ice-cemented ground (permafrost), the lag of soil particles remaining after ice loss decreases subsequent sublimation. Varying soil-ice ratios lead to differential lag development. Here we report 52 years of sublimation measurements from a permafrost tunnel near Fairbanks, Alaska, and constrain models of sublimation, diffusion through porous soil, and lag formation. We derive the first long-term in situ effective diffusion coefficient of ice-free loess, a Mars analog soil, of 9.05 × 10(−6 )m(2) s(−1), ~5× larger than past theoretical studies. Exposed ice-wedge sublimation proceeds ~4× faster than predicted from analogy to heat loss by buoyant convection, a theory frequently employed in Mars studies. Our results can be used to map near-surface ice-content differences, identify surface processes controlling landform formation and morphology, and identify target landing sites for human exploration of Mars.