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SpaceX founder Elon Musk speaks with the NASA astronaut Bob Behnken at Launch Complex 39A at Kennedy Space Center in Cape Canaveral, Florida, on March 1.Joel Kowsky/NASA

Elon Musk told NASA astronauts' kids ahead of the SpaceX launch, 'We've done everything we can to make sure your dads come back OK'

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Update: SpaceX scrubbed Wednesday's launch due to potentially unsafe weather conditions. The next launch attempt is on Saturday at 3:22 p.m. ET.

SpaceX CEO Elon Musk seemed to get emotional on Wednesday when discussing the astronauts his company is about to launch into space.

Speaking on NASA live TV two hours before the scheduled liftoff, Musk said he felt responsible for the astronauts who were inside his company's Crew Dragon spacecraft. They are set to launch at 4:33 p.m. ET, headed for the International Space Station.

"I felt it most strongly when I saw their families just before coming here," Musk said, pausing for a few seconds and appearing to choke up before continuing. "I said, 'We've done everything we can to make sure your dads come back OK.'"

The astronauts' safety is the "the only priority" for the SpaceX team during the mission, Musk told "CBS This Morning," adding that aspects of the mission had given him sleepless nights.

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Musk, Vice President Mike Pence, NASA Administrator Jim Bridenstine, and the families of Behnken and Doug Hurley on Wednesday.Joe Skipper/Reuters

"I'm the chief engineer of this thing, so I'd just like to say that if it goes right, it's credit to the SpaceX-NASA team. If it goes wrong, it's my fault," Musk said.

The responsibility, he said, was "really all I can think about right now."

"I have to kind of mentally block it because otherwise it would be emotionally impossible to deal with," Musk added.

But he expressed confidence in his company's technology and the safety of the mission.

"The spacecraft and the rocket have gone through literally thousands and thousands of tests and reviews," he said, calling Falcon 9 "a well-proven rocket."

NASA estimates a 1-in-276 chance of crew loss

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Behnken and Hurley in their spacesuits during a dress rehearsal on Saturday, ahead of NASA's SpaceX Demo-2 mission to the International Space Station.SpaceX via Twitter

On Saturday, NASA told Business Insider that it estimated there was a 1-in-276 chance that the flight could be fatal and a 1-in-60 chance that a problem would cause the mission to fail (but not kill the crew).

The risk to the mission is therefore considered about 4.5 times the risk to the crew. This is in part because of SpaceX's advanced emergency-abort system, which a January demonstration proved could fly the Crew Dragon spaceship to safety, away from a doomed Falcon 9 rocket. SpaceX has also worked to limit the risk that space junk, asteroid and comet dust, and other debris might pose to a mission.

The two astronauts, Bob Behnken and Doug Hurley, for their part, have accepted the risk calculated by NASA and SpaceX.

"I think we're really comfortable with it," Behnken told Business Insider on Friday.

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Behnken and Hurley strapped into their seats on the Crew Dragon.NASA via Youtube

Behnken added that since he and Hurley had worked with SpaceX on Crew Dragon for roughly five years, they'd gained more insight into the ways the mission could fail "than any crew has in recent history, just in terms of understanding the different scenarios that are at play."

Estimations of the odds that the mission could fail are based on computer models that lean on real flight data. SpaceX has launched its latest Falcon 9 rocket dozens of times, generating measurements that can be fed into simulations. The company has also completed a full (uncrewed) test flight of its new Crew Dragon vehicle and about 20 flights of its Cargo Dragon spaceship.

"Its evolution has become more and more safe as it's been operated, and that's something that we really do appreciate," Behnken said. "It's just remarkable to see all the other missions that have contributed to the human spaceflight program by, in some sense, being a test mission for us before we had the chance to fly on the Falcon 9."

You can find livestream broadcasts of the launch here.