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for almost seven years NASA's Curiosity

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rover has been exploring Mars let's see

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where it is now the rover is climbing a

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mountain Mount sharp

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that is dry and Sandy today but three

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and a half billion years ago rivers

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lakes and groundwater could be found

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here the white line shows where we'd

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like to send curiosity over the next few

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years

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curiosity recently entered a valley

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between a ridge and cliffs higher up the

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mountain we've been calling this area

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the clay unit because Mars orbiters have

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seen a strong clay signal here that's

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exciting

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because clay minerals often form when

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water is around from the ground we can

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look for clues of ancient water in these

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cliffs above the clay unit the same

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orbiters see sulfate minerals that could

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mean that water was drying up or

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becoming more acidic comparing the clay

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and sulfate layers could give us a

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better idea of how the Martian climate

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changed over time cutting through the

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sulfate layer is evidence of an ancient

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gushing River Gettis Valles channel in

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orbiter images we've seen boulders and

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other debris that were probably washed

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out by the river this channel formed

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after the clay and sulfate layers it's a

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whole other chapter in the story of

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water on Mount sharp these features

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could teach us about more than just the

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mountain they may help explain what

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changes were happening across Mars at

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the same time and how that affected its