nai

Project Progress

Last year’s work resulted in a paper by Schorghofer (2005) about ground ice in Beacon Valley, Antarctica. Another study by Schorghofer and Edgett (2006), on observations of seasonal ice at low latitudes on Mars, meanwhile made the journal’s hotlist of most downloaded articles. Since completion this work, also briefly summarized in last year’s project progress report, we have carried out the following investigations.

Ground ice exists on Mars poleward of 60 degrees latitude on both hemispheres, and its persistence is well understood theoretically. The paper by Aharonson and Schorghofer (2006) applies this theory and, combined with high resolution measurements of topography, evaluates the stability of ground ice on cold pole-facing slopes. The resulting maps, shown in Figure 1, indicate patches of ice are expected at substantially lower latitudes than for a smooth surface.

Preliminary work has been done on hydration and dehydration of sulfates under Mars conditions. The calculations provide estimates of the seasonal and diurnal release of water and predictions for the vertical distribution of bound H₂O. This project now awaits new laboratory data on phase relations and kinetics of hydrated sulfates from Dave Vaniman and Steve Chipera at Los Alamos National Laboratory.

Regions rich in subsurface hydrogen exist near the equator of Mars. The hydrogen enhancement may be due to ice, hydrates, or chemically bound hydrogen. Model calculations by Steven Nelli, Bill Feldman, and others suggest nighttime frost forms in these areas. I have estimated the increase in near surface humidity caused by evaporating frost to determine if it would be sufficient to recharge the ground with atmospherically derived water. This study is still ongoing.

{{ 1 }}