Curiosity finds more evidence for watery past and prepares to drill first rock

An area of bedrock called "Sheepbed" which contains many of the whitish, calcium-rich veins.Credits: NASA / JPL-Caltech / MSSS
An area of bedrock called “Sheepbed” which contains many of the whitish, calcium-rich veins.
Click for larger version. Credit: NASA / JPL-Caltech / MSSS

The Curiosity rover is almost ready to drill into its first rock in a matter of days, and in the meantime has found more evidence that this region in Gale crater was once much wetter than it is now.

At the press briefing yesterday, mission scientists presented the latest analysis results of the bedrock and other features of interest in the area.

One major discovery is that many of the rocks here have very distinct light-coloured mineral veins, similar to those seen previously by the Opportunity rover. Analysis by the ChemCam instrument has shown that they are composed of calcium, sulfur and hydrogen. The vein material is most likely hydrated calcium sulfate, such as gypsum or bassinite. This indicates that the rocks were once saturated with water, with the water depositing the minerals in cracks in the rocks.

A previously examined feature called Rapitan, a mottled-looking “crust” on another rock, is composed of the same minerals and is thought to be an exhumed vein.

The mineralogical composition is different in this location than in the former streambed where the rover first landed. As project scientist John Grotzinger explains:

“The orbital signal drew us here, but what we found when we arrived has been a great surprise. This area had a different type of wet environment than the streambed where we landed, maybe a few different types of wet environments.”

Other features such as cross-bedded layering and small nodules thought to be concretions, also point to a watery past here.

The rover is also now just days away from drilling into a Martian rock for the first time. The target, called John Klein, is a flat piece of bedrock suitable for drilling. It is named after John Klein, former mission project manager, who died in 2011.

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