Elon Musk's SpaceX is getting ready to launch its upgraded Falcon 9 rocket to the International Space Station, after a series of delays.
It's the first time the rocket is being used in a mission, and will be a crucial test for SpaceX – when it launched the older version of the Falcon 9 in June, take-off failed due to a technical fault in the upper stage of the rocket.
SpaceX is competing against Boeing for commercial contracts from Nasa, so showing it has successfully upgraded the vehicle is important.
Key improvements to the previous Falcon 9 model include new Merlin 1D engines and bigger fuel tanks.
This mission will involve the delivery of 11 communication satellites to the ISS, but after take-off they will attempt to land part of the rocket back on solid ground – the first time it has done this.
It was supposed to take off earlier this month, and then again yesterday, but both times it had to be delayed due to weather conditions.
The take-off is scheduled for 8.33pm local time from Cape Canaveral in Florida – the early hours in the UK.
Launch & landing can be seen on the https://t.co/bDd3GxQXMC webcast or in person from Cape Canaveral public causeway at 8:33pm local tmrw— Elon Musk (@elonmusk) December 21, 2015