Do We Still Have the Right Stuff?

A strong chance exists that, in the next few years, American astronauts will leave low-Earth orbit for the first time in half a century. There is a decent chance that, later this decade, they will return to the moon. A few years after that, they might even reach Mars. NASA is slowly emerging from its lengthy post-Apollo doldrums. A pair of billionaire-backed new entrants in the private sector are making significant technological breakthroughs. Even better, they are driving down costs.