Hudson, Troy L. and Aharonson, Oded (2008) Diffusion barriers at Mars surface conditions: salt crusts, particle size mixtures, and dust. Journal of Geophysical Research E, 113 (E9). E09008. ISSN 0148-0227 http://resolver.caltech.edu/CaltechAUTHORS:HUDjgre08
- Published Version
Restricted to Repository administrators only
See Usage Policy.
Use this Persistent URL to link to this item: http://resolver.caltech.edu/CaltechAUTHORS:HUDjgre08
The diffusion coefficient of water vapor through porous media at Mars-like surface conditions is measured for a variety of complex particle size distributions and soil compositions. Micron-sized dust simulants, mixtures of sand- and dust- sized particles, and salt- encrusted sand are examined. We find that while the value of the diffusion coefficient, D, can be reduced by up to a factor of 10 for heavily salt- encrusted soils (minimum observed D = 0.4 ± 0.04 cm^2 s^-1), moderate amounts of salt only produce minor reductions in D. Mechanical packing of pure dust can lower D by a similar amount, while mixtures of dust with sand- sized particles produce at most a factor of ~4 reduction. We conclude that present- day processes of aeolian redistribution, moderate levels of salt encrustation, and volatile loss from dirty ice would be inefficient at producing soil deposits and lags on Mars that pose significant barriers to diffusion. Therefore, subsurface ice deposits that are thermally unstable would not be protected against sublimative loss by such materials.
|Additional Information:||© 2008 by the American Geophysical Union. Received 22 October 2007; revised 27 February 2008; accepted 4 June 2008; published 18 September 2008. We gratefully acknowledge the assistance of Matt Siegler and Han Man in the preparation and performance of experiments listed here. We wish also to thank Norbert Schorghofer for his advice and scrutiny of early paper drafts. Finally, we are indebted to Barney Farmer for suggesting that experiments using dust mixtures were important in understanding vapor transport on Mars. This work was funded in part by the JPL Director’s Discretionary Fund and by NASA’s Mars Fundamental Research Program.|
|Subject Keywords:||polar layered deposits; ground ice; Knudsen diffusion; porous-media; liquid water; pore-size; subsurface; simulations; mineralogy; stability|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||22 Apr 2009 18:24|
|Last Modified:||26 Dec 2012 10:48|
Repository Staff Only: item control page