While NASA's robot is taking photos of Martian rocks, there are several pieces of the real thing on Earth. In 2011, an extremely rare event happened in Morocco — people observed a meteorite fall and recovered it before it was contaminated by water or organisms from Earth. Scientists now describe how it was made, and what it's made of. Now this weekend a piece of the asteroid is up for sale at a pricy auction house in Manhattan. Science and art have converged in a piece of Martian rock.