Curiosity Rover finds evidence of an ancient lake on Mars

Mount Sharp on Mars could be the proof that there was once water on the Red Planet’s surface. The very shape and size of the mountain, scientists report, are most likely the consequence of sediments deposited by ancient rivers rather than the consequence of a meteor impact.

Layered rocks observed by Curiosity and suggesting past water activity (credit: NASA/JPL-CALTECH/MSSS)

Layered rocks observed by Curiosity and suggesting past water activity (credit: NASA/JPL-CALTECH/MSSS)

Since its landing on Mars on August 6th 2012, the Rover Curiosity has been exploring the bottom of Gale Crater heading towards Aeolis Mons, a 5.5-km-high mountain unofficially known as Mount Sharp. Along the way, the rover collected and analysed several rocks and found evidence suggesting that water was running downhill from the crater rim towards Gale’s centre where it would have pooled. The lake would have dried out and reappeared several times in a distant past laying down the sediments that stand out today as Mount Sharp – wind erosion over many hundreds of millions of years would have also removed material between the crater’s rim and what is now the edge of the mountain.

Elevation model of Gale Crater (credit: ESA/DLR/FU BERLIN/G. NEUKUM)

Elevation model of Gale Crater (credit: ESA/DLR/FU BERLIN/G. NEUKUM)

In its drive due south towards Mount SharpCuriosity found conglomerates of pebbles that were probably deposited by rivers, but as it continued south and uphill it found sandstones tilted in the same direction, towards the mountain. This is compatible with the water-flowing model rather than with the idea that the crater would have formed from the ground rebounding after the impact of an asteroid or a comet.

The diagram shows how Mount Sharp might have formed from water sediments and wind erosion (credit: NASA/JPL-CALTECH)

The diagram shows how Mount Sharp might have formed from water sediments and wind erosion (credit: NASA/JPL-CALTECH)

This is something that the team suspected even before landing: “That’s why the landing site was selected” – Professor John Grotzinger, Curiosity project scientist, says. “There was no way to have recognized this from orbit”, “All that driving we did really paid off for science. It didn’t just get us to Mount Sharp – it gave us the context to appreciate Mount Sharp” – he added.

As almost always in science, with one answer come many other questions – “How persistent might the water have been through time on Mars?”, also “How did Mars have enough water in its atmosphere to keep the lake in Gale Crater from evaporating for long periods of time?” and finally “Could temporary climate fluctuations form what we see geologically, or do we need longer term warm wet climate?” Scientists hope to answer all these questions over the next months and years as Curiosity climbs the mountain and studies its surface.

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Carlo Bradac

Carlo Bradac

Dr Carlo Bradac is a Research Fellow at the University of Technology, Sydney (UTS). He studied physics and engineering at the Polytechnic of Milan (Italy) where he achieved his Bachelor of Science (2004) and Master of Science (2006) in Engineering for Physics and Mathematics. During his employment experience, he worked as Application Engineer and Process Automation & Control Engineer. In 2012 he completed his PhD in Physics at Macquarie University, Sydney (Australia). He worked as a Postdoctoral Research Fellow at Sydney University and Macquarie University, before moving to UTS upon receiving the Chancellor Postdoctoral Research and DECRA Fellowships.

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