NASA is planning a mission to redirect an asteroid into orbit around the moon. The space agency has identified a number of potential asteroid candidates. Once chosen, NASA will launch a robotic mission to visit the asteroid. When this robotic spacecraft arrives at the destined asteroid, it'll gather a multi-ton boulder and redirect it toward the moon. A team of astronauts will then visit the boulder in orbit and collect samples to bring back to earth. The Asteroid Redirect Mission [ARM] is set to kick off in early 2020s. It's part of NASA's plan to test and advance technologies required for Mars mission in the 2030s.