Mars Curiosity rover finds unexpected evidence of water:
The key to understanding whether Mars was ever habitable is water. For life as we know it to thrive, liquid water needs to be present — and we know that even though it is now dry, there was once liquid water on the surface of Mars. However, the history of water on Mars is complex, and scientists are still debating exactly how long water was present there and when the planet dried up.
And it's about to get more complex. Recently, the Curiosity rover has made an intriguing discovery suggesting that water was once present in an area that scientists had thought would be dry.
[...] The unusual thing about this discovery is its location — the rover is currently climbing up a mountain called Mount Sharp, where the oldest layers of rock are at the bottom and younger layers are at the top. At the point the rover is currently located, around half a mile from the mountain's base, the researchers expect to find drier conditions — but instead, they found this evidence that there was once a shallow lake here.
[...] "The wave ripples, debris flows, and rhythmic layers all tell us that the story of wet-to-dry on Mars wasn't simple," Vasavada said. "Mars' ancient climate had a wonderful complexity to it, much like Earth's."
