Space X founder and CEO Elon Musk says he envisions a future when we will revisit the Moon and land a man on Mars for the very first time. Musk dreams of the day when reusable rockets will transport people to the Moon and Mars and he’s focusing on humans becoming a multi-planet species. “Sending crews to Mars in four years, I think that’s sounds pretty doable, Musk says. “Internally we’ll aim for two years, but in reality it might be four.” Musk speaks to Time Magazine editor-at-large Jeffrey Kluger on CBS Sunday Morning.