The SpaceX Falcon 9 rocket sits at Launch Complex 39A.
Twelve minutes into the flight, NASA announced that the Crew Dragon spacecraft had separated from the Falcon 9's second stage, which meant that spacecraft was in its desired orbit.
Image Source: John Raoux/AP/Shutterstock10-year-old Jack Hurley waves at his dad, NASA astronaut Douglas Hurley, as Hurley and fellow astronaut Robert Behnken depart the Neil A. Armstrong Operations and Checkout Building on their way to Pad 39-A at Kennedy Space Center.
The SpaceX Demo-2 launch originally was scheduled for Wednesday, but it was called off less than 20 minutes before liftoff due to inclement weather.
In the years since NASA ended its own Space Shuttle Program, NASA astronauts have had to resign themselves to traveling to Russian Federation to train on its Soyuz spacecraft.
With the on-time 1922 GMT liftoff, SpaceX, founded by Musk, the Tesla electric-car visionary, became the first private company to launch people toward/into orbit, a feat achieved previously by only three governments: the US, Russia and China.
During a post-launch news briefing, Kathy Lueders, NASA's program manager for commercial crew noted that Hurley and Behnken have been nicknamed the Dads.
"Today was just an wonderful day", NASA administrator Jim Bridenstine said after the successful launch on NASA TV.
Asked why he felt it was important to be in Florida for the launch, given all that is going on in the country, Mr Trump said it was a "great inspiration" for the country.
The president watched the launch from the rooftop observation deck of the Kennedy Space Center in Florida.
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Saturday's blast off went smoothly, with the first booster stage of the rocket separating cleanly and landing upright on a barge off the Atlantic coast.
Dubbed Demo-2, this is a test flight.
NASA Administrator Jim Bridenstine tweeted, "For the first time in 9 years, we have now launched American astronauts on American rockets from American soil". "I would be surprised if it took more than four" years, he said.
Behnken and Hurley will rendezvous with the International Space Station (ISS) in approximately 24 hours, when the Crew Dragon will autonomously dock. SpaceX is receiving $135 million from NASA to support the first phase of Starship's development as a potential lunar lander, to be used on NASA Artemis missions by as early as 2024.
The project has experienced delays, explosions, and parachute problems - but even so, SpaceX has beaten its competitor, aerospace giant Boeing, to the punch.
"That was a handsome sight to see and I hope you all enjoyed it", Mr Trump said after the launch.
A SpaceX capsule exploded on the test stand past year.
If Crew Dragon proves safe, it may ferry more than astronauts.
The mission is technically considered by SpaceX and NASA to be a test flight.
"What Elon Musk has done for the American space program is he has brought vision and inspiration that we hadn't had" since the shuttle's retirement, Bridenstine said. The Crew Dragon capsule will then dock with the station and deliver its passengers and cargo. "Similar to when the first commercial airline flights began, I think the world will be changed forever".