Nasa and SpaceX are preparing for the first manned launch to take off from American soil since 2011.
The world will be watching eagerly to see how astronauts Robert Behnken and Douglas Hurley fair on their journey to the International Space Station (ISS) on Wednesday.
They will be on board a Crew Dragon capsule, blasted into space by a Falcon 9 rocket built by SpaceX.
Here is how you can watch this historic moment as it happens:
– When is the launch due to take place?
The lift-off is planned to take place at 4.33pm local time on Wednesday, from Nasa’s Kennedy Space Center in Cape Canaveral, Florida.
This works out at 9.33pm British summer time.
– How can I watch the launch?
Nasa is streaming the launch live on Nasa TV, which is available to watch on YouTube at: https://www.youtube.com/watch?v=Aymrnzianf0
Coverage will start at 5pm UK time, so you can get a glimpse of last minute preparations, interviews and more in the lead up to the big moment at 9.30pm.
– Why is this mission so important?
The mission, known as Demo-2, will allow the US to once again send humans into space rather than relying on paying Russia for a lift on their spacecraft as they have done for the past nine years.
According to Nasa, this is a demonstration mission to show SpaceX’s ability to ferry astronauts to the space station and back safely.
It is the final major step required by SpaceX’s astronaut carrier, the Crew Dragon, to get certified by Nasa’s Commercial Crew Programme for more long-term manned missions to space.