WASHINGTON

NASA and private aerospace manufacturer SpaceX are delaying their historic space launch Wednesday after poor weather conditions jeopardized the crew's safety. 

NASA Administrator Jim Bridenstine confirmed on Twitter that the launch will be delayed until Saturday, stressing "safety for our crew members" is the agency's "top priority."

"We'll try, try again to #LaunchAmerica on Saturday with liftoff at 3:22pm ET [1922GMT]," he said. 

The rescheduling was also confirmed by SpaceX, which said the time slot noted by Bridenstine is the "next launch opportunity" for the mission.

When completed, the launch to the International Space Station will not only mark SpaceX's first manned launch, it will be the first privately-developed spacecraft to carry humans into space. It will also be the first time astronauts have been sent into outer space from the US since NASA ended its manned program in July 2011. 

The launch could usher in a new era where private companies, not governments, send people into space. 

Blastoff was slated for 4.43 p.m. local time (2043GMT), but weather around Cape Canaveral, Florida had been dicey with rain, clouds and thunderstorms that ultimately derailed plans.

Bob Behnken and Doug Hurley, the two NASA astronauts that will be carried into space aboard a SpaceX Dragon reusable spacecraft, had been loaded into the vessel hours ahead of launch before it was called off. 

They were driven to the launchpad in Tesla Model X's, the luxury SUVs built by CEO Elon Musk's electric vehicle company. He is also the CEO of SpaceX.

"This is a dream come true, I think for me, and everyone at SpaceX," Musk said hours before the launch. "If somebody told me in 2002 that I would be standing here with NASA's administrator, meeting the astronauts, and the rocket and spacecraft on Pad 39A, the best pad in the world, it's an honor to be there, I would have thought 'man, I don't know what you're talking about.'"