This segment was originally broadcast on April 6, 2008. It was updated on July 25, 2008.
NASA is serious, very serious, about launching the most difficult mission ever attempted by the human race: putting an astronaut on Mars. The voyage will cover hundreds of millions of miles and take two-and-a-half years for the roundtrip. It sounds like science fiction.
To make it scientific fact, the United States needs to first visit familiar terrain - the moon.
It's been nearly 40 years since Neil Armstrong took one giant leap for mankind and almost as long since the American public was truly captivated by the space program. You may not know it, but as 60 Minutes correspondent Bob Simon first reported this spring, the journey to send humans back to the moon and beyond has already begun.
From the mountains of Utah to the factory floors of Cleveland, from the space center in Houston to the marshes of Virginia, spacesuits are being tested, rockets are being fired, and capsules are being designed. The United States is once again aiming to launch astronauts to the moon and yes, even, to Mars.
"What's impossible? What can't we do if we wanna do it badly enough?" asks Gene Cernan, the last man to walk on the moon. He calls his trip on Apollo 17 a visit to God's front porch. He says anything seemed achievable in those days.
"When I came back from the moon in '72, [I] stood on my soapbox and said, 'We're not only going back to the moon, we're gonna be on our way to Mars by the turn of the century.' I believed it with my whole heart. But my glass has been half empty for the last 30 years. Now, it's half full."
It's half full because NASA is returning to what Cernan calls the romance of space: dramatic human missions to other worlds.
What will propel the astronauts is the new Ares rockets, but they won't be ready until 2015.
"A lot of people don't understand. They say, 'Why can't we go to the moon, we've already been there.' Well, we can't really roll up the garage door and dust off the Saturn V rockets. That whole infrastructure was dismantled after the Apollo program," says Dr. Rick Gilbrech, NASA's exploration chief.
The decision to dismantle Apollo and to cancel possible future trips to places like Mars was made during the Nixon era. Dr. Mike Griffin, NASA's current director, says that was wrong. "It has to rank as one of the colossal mistakes in history," he says.
And that mistake, Griffin says, led to the Space Shuttle, which he believes doesn't generate as much excitement because it never leaves the Earth's orbit. Griffin says Americans are bored by the space program because NASA has run a boring space program. The Space Shuttle will finally be retired in two years. In its place will be the new exploration program called "Constellation."
There is no question Mars is the ultimate goal, but why return to the moon? Why not go straight to Mars?
"If we didn't have a moon, we would. And we could. But it would be much riskier," Griffin says.