Major Tim Peake will make history today by becoming the first British astronaut to visit the International Space Station.
The 43-year-old dad-of-two, from Salisbury, will be blasted into space in a Russian rocket from the Baikonur Cosmodrome in Kazakhstan at 11.03am UK time.
No Brit has undertaken such a mission - or even left Earth - in more than two decades.
There are 70 events across the UK where people can watch the launch - including his hometown of Salisbury and at a school in Gloucestershire.
Travelling with him are Russian commander Yuri Malenchenko and Nasa astronaut Tim Kopra.
The trio will be squeezed into the "descent module" of a tiny Soyuz TMA space capsule, which is only about seven feet long.
At launch, the 162 ft rocket generates 422.5 tonnes of thrust - a total of 26 million horsepower.
Before lift off the crew have to endure a tense wait of an hour or more in the capsule, during which they can listen to play lists of selected music.
The three songs Major Peake chose were:
- Queen - Don't Stop Me Now
- U2 - Beautiful Day
- Coldplay - A Sky Full Of Stars
At a press conference Major Peake said what he was looking forward to most was his first glimpse of Earth seen from space: