As the Mars rover Curiosity, a $2.5 billion robot the size of a Mini Cooper, touched down last night, one billionaire was already planning the next logical step -- sending humans there.
"I'm confident at this point that it can be done," Elon Musk told "Nightline" in an interview at SpaceX headquarters in Los Angeles. "I think we'll be able to send, probably, the first people to Mars in roughly 12 to 15 years. That's my estimate."
Musk, who made his billions as an Internet entrepreneur, wants...Full Story