Author: Lisa Grossman / Source: Science News For the first time, a Mars rover has measured the mass of the rocks beneath its wheels. By taking gravity measurements as it climbed a Martian mountain, Curiosity discovered something surprising: Mount Sharp appears to have been built in two phases —

Mount Sharp, officially known as Aeolis Mons, forms the central peak within a very large crater named Gale that is 155 km in diameter. The mountain stands about 5 km tall, its lower flanks exposing hundreds of rock layers. The rock layers – alternating between lake, river and wind deposits – bear