Working quietly in the background since the days of viewgraphs, a group of space entrepreneurs has long been pitching far-fetched ideas to skeptical moneymen with the fervor of evangelists. Now their viewgraphs—updated to Powerpoint and CAD/CAM—are becoming reality, and metal and fire are streaking through the upper atmosphere into low Earth orbit.

Collectively, they are in the vanguard of a new industry, poised to transform how humans venture into space in ways that most observers can scarcely imagine today. Space entrepreneurs had a big influence on aerospace in 2009, although it does not begin to compare with the impact they are likely to have in years to come.

That is why Aviation Week chose this intrepid group of engineers and visionaries as the 2009 Person of the Year.

Two developments have set the stage for space entrepreneurs to begin breaking down barriers, financially and otherwise. After investing more than $1 billion in hard-won private capital on hardware, they are finding increased acceptance for their business plans. And they have finally made it to space with humans onboard—three suborbital flights with SpaceShipOne that won Scaled Composites the Ansari X-Prize and launched a fledgling commercial space-tourism business.

Traditionally reluctant to rely on government backing, these brash businessmen now find themselves at the center of the debate on how government astronauts will get to space; the very governments they have often disdained are potentially their biggest customers. NASA already has multi-billion-dollar contracts with two of them to deliver cargo to the International Space Station and is spending big bucks to encourage them to develop more capability.

In the U.S., where almost all of the space entrepreneurs operate, the federal government may wind up relying on them to transport astronauts to the ISS. And, building on the success of the X-Prize Foundation in spurring development of a privately financed human spaceship, NASA and Congress are using a federal prize program to tap into the skills of the growing entrepreneur community.

As Burt Rutan at Scaled Composites was putting the finishing touches on SpaceShipTwo, the commercial version of the vehicle that won the privately backed $10-million X-Prize, another Mojave, Calif.-based company was winning big, too. Masten Space Systems pulled in more than $1 million in federal Centennial Challenge prizes for building a lunar-lander prototype and proving it on a simulated moonscape.

Mojave is a hotbed of the space-entrepreneurial spirit, and Dave Masten—featured on the cover with his prize-winning rocket-powered Xoie lander—epitomizes that zeal. Like some other space entrepreneurs, Masten got his start in information technology, but winning the Centennial Challenge lunar lander prizes make it less likely the longtime rocket buff will ever have to go back to Silicon Valley.

At first sight, the Masten Space System’s Mojave facility seems like an unlikely incubator for breakthrough developments in reusable space-access technology. Yet, like so many of the new breed of space entrepreneurs, the Masten team is working in less-than-perfect circumstances to rewrite the rule book.

The company’s ex-Marine Corps hangar, built as a temporary structure more than 60 years ago, combines the hobby-shop look of a Mythbuster TV studio with the 1940s can-do atmosphere of the early Lockheed Skunk Works. From here, Masten has developed and tested prototypes of what he hopes will soon turn into a series of fully reusable vertical-takeoff, vertical-landing launch vehicles.