Organizers of the X Prize believe that teams could attempt the space trip as early as this summer.
When the competition was announced eight years ago, many were skeptical that any privately financed team could meet the requirements to collect the prize: Build a spacecraft capable of taking three passengers 62.5 miles above the planet, then make a second successful suborbital trip within two weeks.
"It's going to happen in 2004. Someone will win it," said Gregg Maryniak, director of the St. Louis-based X Prize Foundation, a group created to spark development of reusable spacecraft that can take average citizens into space.
Many of the teams vying for the X Prize already have conducted test launches. One U.S. team propelled a spacecraft to 68,000 feet, or about 13 miles. While a couple of U.S. teams are among the top contenders, crews from six other nations also are in pursuit of the prize.
It's a diverse group tapping into the same spirit of exploration that led adventurers to sail ships across unknown oceans. Teams range from one financed by a billionaire to a group of scraped-together volunteers. Several boast leading minds who toss around aerospace terms with dizzying precision. Others lament unexpected fires and explosions as part of the learning process.
Safety is stressed, but team members know they're embarking on a journey with built-in risks, maybe even death.
"It's a possibility. It's a cost that exploration has to pay. Otherwise, you stay home and watch TV and eat French fries," said Pablo de Leon, the 39-year-old team leader of an Argentinian group that is building a vertical rocket named Gauchito, or The Little Cowboy.
"If we are not the ones, someone else will do it. But it will be done," de Leon said.
Canadian Brian Feeney, 44, is team leader of the Toronto-based da Vinci Project. In its simplest terms, the group wants to lift a spacecraft called Wild Fire using an immense helium balloon. The design switches over to rockets to fly and uses a parachute to land.
Feeney plans to be on board for the first manned attempt. He said he thinks of the risk as similar to that of climbing Mount Everest, the world's tallest peak. "Life is way too short to not explore those boundaries," he said.
"How many times does a kid have a chance to go into space? I'm living my dream," he said. "I feel like I'm limited; my bicycle won't go as far as I want it to. My grandest dream goes all the way to the stars."
Maryniak recounted how space tourism advocate Peter Diamandis read Charles Lindbergh's "The Spirit of St. Louis" autobiography and realized how aviation contests, like the $25,000 Orteig prize awarded to Lindbergh for crossing the Atlantic in 1927, helped launch mainstream air travel.
So the X Prize was announced in 1996. The foundation includes such noted supporters as Dennis Tito, the American who spent $20 million to fly in a Russian craft as the first space tourist, and pilot Erik Lindbergh, the grandson of Charles Lindbergh.
Nine of the 27 teams have built "serious hardware" and four or five are at the leading edge of the competition, Maryniak said.
The top competitors include at least two American teams — Scaled Composites of Mojave, California, and Armadillo Aerospace of Mesquite, Texas. Both have applied to the Federal Aviation Administration to attempt space flight. Another company, which is not competing for the prize, has also applied.
George Nield, the FAA's deputy associate administrator for commercial space transportation, said, "We are getting very close to making a licensing determination for one of those."
Several competitors believe Scaled Composites could take the prize.
Financed by Microsoft billionaire Paul Allen, Scaled Composites is led by aviation pioneer Burt Rutan, perhaps best known for his design of Voyager, an aircraft that circled the globe in a non-stop 1986 flight without refueling.
The Scaled Composites design consists of a rocket plane, called SpaceShipOne, and the White Knight, a jet designed to carry it aloft for a high-altitude air launch. SpaceShipOne traveled faster than the speed of sound in a test on Dec. 17, the 100th anniversary of the Wright Brothers' first flight.
In addition to the prize competition, the foundation and the teams hope for a time when space travel is more accessible, when people can book a trip into space, see the world from a distance and experience weightlessness.
"For a lot of them, the real prize is not the X Prize, it's the commercial business," said Maryniak. "The only thing wrong with space flight is there's not enough of it."