NASA and Elon Musk’s SpaceX rocket company have postponed launching the first crewed space flight from US soil in close to a decade on Thursday morning.
The historic launch would have also been the first time a private company has been trusted to send people into space.
At 6.20am it was announced the launch would be postponed due to bad weather.
SpaceX and NASA will have another go on the weekend, with another opportunity to launch at 5.22am Sunday morning AEST.
NASA administrator Jim Bridenstine explained the decision to scrub the launch a short time after.
“We had just simply too much electricity in the atmosphere,” Mr Bridenstine said.
“There wasn’t really a lightning storm or anything like that, but there was a concern that if we did launch it could actually trigger lightning.
“We made the right decision, we had the parameters set ahead of time, the teams worked together and in the end the right decision was made.”
Mr Bridenstine said that NASA wouldn’t buckle to any pressure when it came to the delicate and dangerous task of sending people into space.
“If we are not ready to go, we simply do not go,” he said.
After that call was made the pair faced around 40 minutes wait inside the SpaceX Crew Dragon capsule as propellant was removed from the rockets.
Waiting ten to fifteen minutes could have been enough for the weather to settle, but Thursdays launch had an “instantaneous launch window” that meant that wasn’t possible.
The last crewed flight to take off from the US was in 2011, after which NASA’s shuttle program was closed down.
Since then it’s relied on collaboration with Russia to transport crew and supplies to the International Space Station.
Thursday’s launch was part of the Commercial Crew Program, in which NASA decided to appoint private companies with the task of building spacecraft to take astronauts and supplies into space.
SpaceX and Boeing were granted approval to participate in the program in 2014, being awarded contracts worth $US3.14 billion ($A4.73 billion) and $US4.8 billion ($A7.23 billion) respectively.
SpaceX would have been the first private company to send a crewed flight to space, and also beat Boeing to getting approval to conduct more crewed flights in the future.
Boeing is expected to get its chance at similar approval next year, after delays and problems with its testing procedures.
SpaceX’s Crew Dragon capsule is designed to separate from its rocket around 12 minutes after launch, then spend the next 19 hours or so chasing down and docking with the International Space Station.