When humans landed on the moon 50 years ago, it felt like space colonization wouldn’t be too far behind. Surely we’d see a settlement on the moon and a colony on Mars by 2019—or even sooner. “To think that we’ve done neither is disappointing,” says Eric Stallmer, president of the Commercial Spaceflight Federation.

But the next 50 years will hold much more promise, according to Stallmer and other experts. “There is a revolution underway in space flight,” says Robert Zubrin, author of The Case for Space. “A well-led entrepreneurial team can do things only the governments of major powers could do, in one-third the time and one-tenth the cost.”

Zubrin credits the efforts of a handful of billionaire entrepreneurs who work quickly and “do things that had seemed completely impossible.” This includes building resusable launch vehicles that greatly reduce costs.