■ 2010: "We do hope to be carrying people to the [International Space Station] in perhaps as soon as three to four years. We want to carry NASA astronauts and we also want to carry private citizens to space."

But first, as Colbert noted at the time, Musk would have to find a way to "bring them back down" -- namely by creating a rocket that could land.

■ 2014: Earlier this month, the Falcon 9 rocket, designed and built by SpaceX, launched six satellites. When the Falcon 9 returned to Earth on Tuesday, it performed a successful soft landing. So while Musk's three-to-four-year timeline was a bit too ambitious, the company has made a major step toward its goal.