Curiosity Rover Steps Right Into Ancient Riverbed on Mars
NASA’s Curiosity rover has found evidence that the area in Gale crater it is traveling through once had vigorously flowing water for perhaps thousands or millions of years. Scientists don’t know exactly how long ago this river would have flowed but it would likely be billions of years in the past. Several pieces of evidence attest to this hypothesis, but the key feature was a strange rock sticking out of the Martian regolith. The rock, nicknamed Hottah, “looked like someone came to the surface of Mars with a jackhammer,” said John Grotzinger of Caltech, project scientist for the mission, during a NASA press conference, adding that it wouldn’t look out of place as a slab of concrete in downtown L.A.
Detailed observation of the rock showed that it was a composite, essentially a rock made of other rocks. The tiny rocks, called clasts, were embedded in the overall structure and appeared rounded, eroded after being transported by wind or water. The rocks were too large to have been moved by wind, suggesting that flowing water was the cause for their roundness.