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TimberWolf
2005-Mar-15, 05:18 AM
Hello,

Frolm what I gather, the regolith is essentially frozen permafrost. How deep does the regolith go until the layers of bedrock are found?


Cordially,

TimberWolf

HypersonicMan
2005-Mar-17, 09:59 PM
Hello,

Frolm what I gather, the regolith is essentially frozen permafrost. How deep does the regolith go until the layers of bedrock are found?


Cordially,

TimberWolf

Regolith is just a generic term for the loose dust, sand, and rubble found on the surfaces of planetary bodies (basically space dirt). Whether on it is frozen or not or how deep it goes depends on Mars depends on where you are. In the poles its mostly frozen with layers of water and CO2 ice on top and mixed in, but where the rovers are now it is bone dry. I'm guessing that the etched terrain in Meridiani is probably lots of exposed bedrock, but I'm hoping we'll find out first hand. I think the near-surface water on Mars is probably bound up in hydrates, but it is probably frozen ice or even liquid brine some distance below. Many aspects of the Martian subsurface are still very much unknown.

JonClarke
2005-Mar-20, 11:26 AM
Regolith is basically everything between fresh rock and fresh air and its found on all solid planets. It includes surficial sediments, both loose and indurated, soil weathered rock, and shallow groundwater (frozen and unfrozen), and biota (if present). On bodies such as the moon and Mars, it can be useful to differentiate between the regolith proper, which is the near surface weathered and impact-gardened material, and the megaregolith, which includes the upper few km of crust, both sediments and lava flows, that have been fractured by impacts.

Permafrost is on earth is regolith that is permanantly below the freezing temperature of water, whether or not water is actually present. On Mars of course the whole surface is permafrost, from a depth of a few mm to huhdreds or 100's of m. On Mars regionally most of the planet north and south of 60 degrees contains >20% water (and thus in most cases ice) in the top m of the regolith. Nearer the equator ice is probably present at great depths (100's of m) but may be shallower locally in a metastable form because of comparitively recent climatic changes or outflow events.

Jon