SpaceX's Falcon 9 rocket radiantly rose into a serene predawn sky over Florida on Tuesday, successfully launching a privately-owned capsule named Dragon into orbit on a seminal test flight to the International Space Station.

Liftoff occurred at 3:44 a.m. EDT (0744 GMT). Credit: Walter Scriptunas II/Spaceflight Now
 
The Dragon spacecraft is on a technological shakedown mission, and if all goes according to plan, it will become the first commercial vehicle to reach the space station, a 450-ton orbiting complex staffed by six crew members from the United States, Russia and the Netherlands.

Founded in 2002 by Elon Musk, an Internet mogul who helped start PayPal, SpaceX has spent $1.2 billion designing and building rockets and spacecraft intended to cut the costs and boost the reliability of space travel.

NASA has paid $381 million to go toward developing the company's Falcon 9 rocket and Dragon cargo spacecraft. The public-private partnership allows SpaceX to work with public financing and private capital.

SpaceX also has a $75 million agreement with NASA to begin modifying the Dragon spacecraft to carry astronauts, a feat the company says is achievable, assuming continued NASA support, by 2014 or 2015.

But the craft's first job is to reliably deliver cargo to the space station. Since the retirement of the space shuttle, NASA has been dependent on Russian, European and Japanese vehicles for resupply duties. Russia's Soyuz capsule is the sole vehicle capable of crew transportation to and from the space station.

The mission launched Tuesday is the SpaceX's biggest test yet. NASA plans to use the Dragon spacecraft for 12 operational cargo delivery flights beginning as soon as this year, and a modified version of the Dragon is in the running to be the next U.S. spacecraft to fly humans into orbit.

But NASA officials need to see how the Dragon capsule performs in space before placing precious experiments or priceless human lives aboard. The nine-day flight launched Tuesday aims to help put those concerns to rest.

The Falcon 9 rocket flashed to life and ascended from the launch pad at 3:44:38 a.m. EDT (0744:38 GMT), the moment Earth's rotation moved the seaside facility into the space station's flight path.

Liftoff came three days after computers ordered a last-second abort after detecting high pressure in one of the Falcon 9 rocket's nine main engines. Engineers traced the problem to a faulty nitrogen valve and replaced the part, clearing the way for another try Tuesday.

Soaring into a cloudless, star-filled sky, the rocket remained in view of spectators for several minutes, appearing first as a ball of orange fire, then a brilliant moving star as it trekked northeast from Cape Canaveral, Fla.

The 15-story booster reached orbit and deployed the Dragon spacecraft less than 10 minutes after its thunderous departure from Cape Canaveral, following a seemingly perfect trip to space powered by 10 kerosene-fueled Merlin engines.

Moments after its release from the Falcon 9 rocket, the Dragon capsule shed aerodynamic shields over its solar panels before unfurling the arrays to generate electricity. It was the first time the SpaceX-designed solar wings flew in space.

"Feels like a giant weight just came off my back," Musk tweeted shortly after launch.

Describing how he felt at the moment of liftoff, Musk said: "Every bit of adrenaline in my body released at that point."

Tests of the Dragon's GPS navigation system, high-tech optical and thermal rendezvous sensors, and abort functions were planned later Tuesday. A bay door housing the rendezvous systems opened as planned and locked into place, exposing the Dragon's laser range-finder and grapple fixture.

"Although there's a lot ahead to complete this mission, we're certainly off to a good start," said NASA Administrator Charles Bolden.

A series of orbit-raising burns of Dragon's thrusters was planned Tuesday and Wednesday. Shifts of controllers at SpaceX's Hawthorne, Calif., headquarters will watch over the spacecraft throughout the mission.

"We obviously have to go through a number of steps to berth with the space station, but everything is looking good," Musk told reporters after launch. "I would really count today as a success no matter what happens with the rest of the mission."

If all goes according to plan, the gumdrop-shaped capsule will close in on the space station Thursday, exercising its long-range navigation systems and testing a communications link with the complex. The space station crew will use a control panel to issue a demonstrated command to the Dragon spacecraft, verifying the communications path between the station and the capsule is stable.

Dragon's closest approach to the space station Thursday will be about 1.5 miles below the complex before a rocket burn sends the capsule away for a day while engineers on the ground analyze the spacecraft's performance.

A second rendezvous with the space station Friday will culminate with the Dragon closing to a distance of 10 meters, or about 32 feet, beneath the orbiting lab, close enough for NASA flight engineer Don Pettit to grapple the capsule with the station's robotic arm.

The grapple is scheduled for approximately 8:06 a.m. EDT (1206 GMT) Friday. The space station crew will guide the Dragon spacecraft on the robotic arm to a port on the Harmony module.

The station residents will open hatches leading to the Dragon on Saturday, beginning work to unload nearly 1,150 pounds of bonus supplies hauled into space inside the Dragon, including food, crew provisions, student-developed experiments, and computer equipment.

The crew will install experiment hardware, broken parts, and used spacewalking gear into the Dragon's pressurized cabin for return to Earth.

The capsule is due to depart the station and fly to a parachuted splashdown in the Pacific Ocean on May 31.