They are self-confessed practical jokers but, from tonight, the last laugh is going to be on them.

Meet the country's most gullible 'space tourists', who are unwittingly taking part in the biggest hoax in TV history.

All of them believe they are at a former Soviet military base preparing for a trip into space with Russia's Space Tourism Agency for a new reality show.

The brutal truth is they are not. They are at an old airbase in Suffolk - and will remain there. A special effects company made their 'rocket' for the film Space Cowboys and they will be shown video images of Earth through its windows.

Three actors have secretly joined the contestants, aged between 19 and 28, to help pull the wool over their eyes. The three most gullible candidates will be chosen to go to 'space in a rocket' with one of the actors.

The new Channel 4 show almost crashlanded before it began, though.

On their plane flight from England to 'Russia', the cadets nearly saw Canary Wharf as they came in to land after circling the English Channel for three hours.

However, a quick-thinking producer of Space Cadets started a singalong to stop them looking out of the windows.

When they got out, one of them observed: 'It's bloody cold in Russia.'

Presenter Johnny Vaughan will keep tabs on their progress until he finally reveals the hoax to them on December 16.