For more than two hundred years, astronomers have been wondering what asteroids are actually like. They believe that these primitive rocks have been concealing countless secrets for billions of years. From the depths of space to laboratories on Earth, scientists are trying to unlock these secrets. The rocks are time capsules that will allow them to go back in time to the formation of the solar system, and the creation of Earth. Recently, major space agencies around the world have sent unmanned missions to asteroids. The most daring ones are collecting asteroid samples and bringing them back to Earth. These expeditions hold a host of surprises for researchers and shake up our understanding of asteroids.