SpaceX founder Elon Musk was choked up with emotion after his company successfully launched astronauts to space for the first time on Saturday (May 30). 

"I'm really quite overcome with emotion on this day, so it's kind of hard to talk, frankly," Musk said in a post-launch press conference at NASA's Kennedy Space Center in Florida Saturday evening. "It's been 18 years working towards this goal, so it's hard to believe that it's happened."

Musk's comments came a few hours after SpaceX's Falcon 9 rocket lifted off from the center's historic Launch Complex 39A, carrying a Crew Dragon spacecraft with NASA astronauts Bob Behnken and Doug Hurley on board. 

By successfully launching its new Crew Dragon spacecraft with astronauts on board for the first time, SpaceX became the first private company to launch astronauts for NASA. The crewed test flight, called Demo-2, is also the first crewed launch from the United States since the space shuttle program ended in 2011. SpaceX and Boeing were both selected for NASA's commercial crew program to wean the agency off its dependence on Russia's Soyuz to fly  astronauts after the shuttle program was retired.