SpaceX says ‘all systems are go’ to launch NASA’s longest, most ambitious astronaut mission yet on Sunday night

SpaceX says ‘all systems are go’ to launch NASA’s longest, most ambitious astronaut mission yet on Sunday night

NASA has given SpaceX the green light to proceed with its most crucial mission yet: launching four astronauts to the International Space Station.

The Crew-1 mission was set to launch Saturday but mission managers bumped the flight to Sunday due to weather and technical issues.

SpaceX said on Sunday morning that "all systems are go" for a launch at 7:27 p.m. ET. However, launch site weather conditions have a 50% chance of delaying the mission to Wednesday.

If successful, Crew-1 will be NASA's longest spaceflight ever and the first aboard a human-certified commercial spacecraft.

Final launch preparations help "keep the nerves down," says Crew-1 commander Mike Hopkins.

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NASA has given SpaceX the go-ahead to launch its first full crew of four astronauts toward the International Space Station