[X] My Assistant

[Guest_Sunspot_*]

When the original news of Opportunity's watery finds at Merdiani were announced in early 2004 .. we had a region of Mars that to quote NASA was "drenched in water" with long standing pools or lakes on the surface.

However, the most recent science results all refer to "ground water" rather than surface water producing the concretions etc. It also seems that much of the bedrock making up the walls of Endurance Crater... and Victoria Crater are vast "fossilised" dune fields - not very watery at all. Is the story of water at Merdiani drying up?

[nprev]

Not to sound completely parochial, but I literally grew up on a mine dump that had very little annual precipitation and a deeply buried water table: Butte, Montana, site of the Berkeley Pit copper mine. Spent many, many happy days roaming the dumps with my eyes turned to the ground, looking for interesting rocks & the odd ancient mining tool...

There were two notable features of these old dumps that may be applicable to this discussion:

1. In the presence of any liquid water at all, metallic precipitates readily formed. In the case of Butte, these were usually copper salts; at Meridiani, the direct analog would be blueberries.

2. The dumps were covered with an extremely tough and very thick layer of duricrust (I know; I had ten stitches in one of my knees from an unfortunate fall). This was probably due to a combination of atmospheric water vapor and the annual snow melt. The rather extraordinary 'paved' quality of Merdiani Planum observed by Oppy (and its ability to support the rover's weight) suggests that the mechanical properties may be similar.

No conclusions offered, merely observations!