MOJAVE, Calif. - Legendary aircraft designer Burt Rutan and his small cadre of pilots and engineers fueled the privately-funded SpaceShipOne rocket plane Sunday and ran through a final few flight simulations in preparation for a history-making launch to the edge of space Monday.

The carrier aircraft with SpaceShipOne mounted beneath during an earlier test flight. Credit: Scaled Composites

With 62-year-old test pilot Mike Melvill at the controls, the innovative SpaceShipOne is poised for its most ambitious test flight, a voyage Rutan believes could open the door to a new era in aviation history.

"We want our children to go to the planets. We are willing to seek breakthroughs by taking risks," Rutan said at a crowded afternoon news conference. "And if the business-as-usual space developers continue their decades-long pace, they will be gazing from the slow lane as we speed into the new space age. This time, not for prestige but this time, to fulfill people's dreams.

"Yes, we will be doing barnstorming, just like the early airplanes. However, we're heading for orbit sooner than you think. And we know it's crucial to dramatically reduce the cost. We do not plan to stay in low-Earth orbit for decades, but to enable high adventure and exploration as soon as the new technologies allow. And so, hold on! The next 25 years will be a wild ride. That's my prediction, (a wild ride) that historians will note that was done for the benefit of everyone."

Takeoff is targeted for around 9:30 a.m. EDT (1330 GMT), weather permitting. The only issue, Rutan said, was a possibility for higher-than-allowable crosswinds at the desert runway. But otherwise, the spaceship was ready to go.

Rutan's company, Scaled Composites, is famous in aerospace circles for its unique aircraft designs. But SpaceShipOne is its first venture into the previously governments-only world of space flight. Financed by Microsoft co-founder Paul Allen, Rutan hopes to win the X-Prize, a privately funded $10 million award to operators of the first passenger-carrying commercial craft to reach 62.5 miles twice in two weeks.

"Tomorrow, we will attempt to add a new page to the aviation history books," Allen said. "If our attempt is successful, SpaceShipOne will be the first privately funded spaceship to reach sub-orbital space. SpaceShipOne's pilot will also become the first civilian pilot to ever cross the boundary of space in a completely privately funded vehicle.

"I'm extremely proud to be part of what I think is one of the most challenging and rewarding initiatives taking place in the field of aviation and aerospace today."

While Allen has pumped more than $20 million into the SpaceShipOne project since March 2001, he and Rutan believe they can achieve a sizeable return on their investment if they can perfect the technology and eventually lower the cost of a ticket to around $10,000 or less.

"I strongly believe that if we are successful, our program will mark the beginning of a renaissance for manned spaceflight," Rutan said in an internet statement. "We need affordable spaceflight to inspire our youth, to let them know than they can experience their dreams."

Asked what he thought about the historical significance of opening the high frontier to the common man, Rutan said today it was the "realization that hey, this is for us to do now, this is not only for governments to do. I believe the real significance of this program is that realization, and I believe that realization will attract investment and that realization will attract a whole bunch of activity. And very soon, it will be affordable for you to fly."

The target for Monday's flight is the same as the target for the X-Prize, an altitude of 100 kilometers - 62.5 miles - the somewhat arbitrary definition of where the discernible atmosphere ends and outer space begins.

This illustration shows the flight profile for SpaceShipOne. Credit: Scaled Composites

Like NASA astronaut Alan Shepard's historic flight aboard a Mercury spacecraft in 1961, SpaceShipOne will fly a sub-orbital, up-and-down trajectory.

Even so, SpaceShipOne's flight will mark an impressive milestone. At the target altitude, the air is so thin an aircraft's aerosurfaces - wing flaps, rudder, elevators - no longer function and the vehicle becomes a pure spacecraft. The Federation Aeronautique Internationale, the international body that sanctions aerospace records, recognizes 100 kilometers as the "official" boundary between space and the discernible atmosphere.

While Monday's mission is a test flight and not the first launch in an attempt to win the X-Prize, Rutan is expected to make a run for the coveted prize later this summer or early fall. Other teams are preparing for X-Prize flights as well. But Monday's flight, if successful, will stand alone in the history of space travel.

Scores of reporters, network news crews, free lancers and other media flooded the sun-baked Mojave airport today, creating a carnival-like atmosphere at the desert runway. Thousands of spectators were expected to show up for Monday's flight, prompting airport officials to open designated areas for camping.

"Wow," Rutan said, looking across a throng of reporters and photographers at the news conference. "I've been to two goat ropings and a county fair, and I've never seen anything like this."

He said the pubic and media reaction the flight gave him goosebumps.

"Clearly, there is an enormous pent-up hunger to fly in space and not just dream about it," he said.

Melvill, one of three SpaceShipOne test pilots, is vice president and general manager of Scaled Composites. Originally from South Africa, Melvill holds a variety of aerospace records and is a 1999 recipient of the Iven C. Kincheloe Award for high-altitude test flights in Model 281 Proteus aircraft.

Aboard SpaceShipOne, Melvill will become the first non-government astronaut recognized by the Federation Aeronautique Internationale.

Mike Melvill. Credit: Scaled Composites

"I'm very, very flattered to have been chosen for this," Melvill said today. "The other two guys are every bit as good as me, or better. I just got the short straw or the long straw, whatever it is, and I'm delighted to do it. I enjoyed the last flight, I'm hoping this will be an exact repetition, just a little higher, a little faster. I'm looking forward to it very, very much."

In a parting afterthought, he added: "I'm ready to go, boy, I am ready to go, and we are going to win the X-Prize. Put your money on it."

On the eve of its historic flight, SpaceShipOne sat in its hangar at the Mojave airport, a sprawling civilian test center in the California high desert where scores of aging jet airliners sit parked in long, lonely rows.

Just a few miles away is Edwards Air Force Base, where test pilot Joe Walker reached the edge of space in July 1963 flying an Air Force X-15 rocket plane to an altitude of 67 miles.

Using a flight profile similar to the vastly more expensive X-15's, SpaceShipOne will be carried aloft by another Rutan aircraft, the futuristic-looking twin-turbojet White Knight mothership. Taking off from runway 30, White Knight will carry SpaceShipOne to an altitude of about 46,000 feet, which will put both planes above 85 percent of the atmosphere. At that point, assuming the weather cooperates and there are no technical issues, SpaceShipOne will be released, dropped like a bomb high above the Mojave airport runway.

To help spectators on the ground spot the aircraft, smoke canisters attached to the wings of the White Knight mothership will be fired shortly before the spacecraft is released, producing visible contrails in the stark desert sky.

Falling wings level, Melvill will trim SpaceShipOne's control surfaces for positive nose-up pitch to ensure a steep, vertical climb when its hybrid rocket motor is ignited. Then, 10 to 15 seconds after release, Melvill will fire the motor, boosting the craft nearly straight up.

This file image shows a previous test launch of SpaceShipOne. Credit: Scaled Composites

Burning solid rubber propellant with liquid nitrous oxide - liquefied laughing gas - the powerful rocket motor will accelerate SpaceShipOne for slightly less than 80 seconds or so, subjecting Melvill to a force of around three times Earth's gravity. Engine cutoff, timed to ensure the spacecraft reaches the target altitude, will occur between 140,000 and 170,000 feet (26.5 to 32 miles) depending on actual performance and atmospheric conditions.

Shuttle boosters burn a rubbery mixture of propellant and oxidizer. Once ignited, a shuttle booster cannot be shut down and burns until the fuel is depleted. In contrast, SpaceShipOne's motor uses liquid nitrous oxide to provide the oxygen necessary for operation. Should a problem develop, Melvill can stop the engine by simply shutting off the flow of nitrous oxide.

Dave Moore, an engineer with Allen's Vulcan Inc., said the motor is inherently safer than pure solid-fuel boosters like the shuttle's and that SpaceShipOne has been thoroughly flight tested to wring out the design. But he quickly added "it's not risk free."

"We're confident things will go fine, but there is the unknown," he said. "It is going to space."

At engine cutoff, SpaceShipOne will be coasting upward at 3.2 times the speed of sound. Following a ballistic trajectory through an altitude of 62.5 miles, Melvill will experience about three-and-a-half minutes of weightlessness as the craft arcs over and falls back into the atmosphere.

SpaceShipOne's re-entry profile is a significant Rutan innovation and a sharp departure from the design philosophy that produced the X-15 and even the space shuttle. Shortly after engine shutoff, still climbing upward at an altitude of 200,000 feet (38 miles) or so, Melvill will "feather" SpaceShipOne's stubby wings, rotating them sharply upward with respect to the craft's fuselage.

An onboard camera shows the SpaceShipOne feathering during an earlier test flight. Credit: Scaled Composites

Feathering is an unusual technique for minimizing re-entry temperatures and stresses and eliminating the need to precisely control the craft's entry orientation. Space shuttles, for example, must re-enter in a carefully controlled orientation with a steep nose-up angle of attack to keep temperatures at or below wing leading edge design limits of about 3,000 degrees.

In contrast, SpaceShipOne's design ensures the vehicle will make what Rutan calls a "care free" re-entry, much like a badminton shuttlecock. With its rear wings steeply tilted, the spacecraft will experience enormous aerodynamic drag, which will force the craft to assume a cabin-level orientation that does not require a precise angle of attack. It also ensures maximum temperatures do not exceed 500 degrees Fahrenheit.

"That innovation allows the craft to return to the atmosphere, as Burt Rutan says, 'care free,'" said Moore. "It allows the craft to gently return to the atmosphere."

After experiencing peak deceleration loads up about 4 Gs, Melvill will swing the wing back down at an altitude of about 60,000 feet. From there, SpaceShipOne will glide back to the runway like a normal aircraft.

Asked if NASA had expressed any interest in the flight, Rutan said astronaut Scott Horowitz planned to be on hand for launch. But he stressed that NASA was not part of his program.

"Every time we went to NASA for help, getting their help meant I couldn't stay under the budget I promised Mr. Allen," he said. "So we decided we had to do this on our own."

In-cabin video shot during the flight, along with other camera views from chase aircraft and fuselage-mounted cameras, are expected to be released shortly after touchdown. Another news conference is planned for later in the morning.