A Sussex spaceman is preparing for the final frontier by travelling to the centre of the earth.

Tim Peake, the UK’s first astronaut in more than 20 years, is taking part in a training expedition with the European Space Agency (ESA).

The father-of-two will be the first Briton to visit the International Space Station when he blasts off in November 2015. He will spend six months in orbit 230 miles above the Earth.

ESA trainers and caving specialists have been travelling 5km underneath Sardinia to prepare a cave which will become the space agency’s training ground this summer.

The cave tests the astronauts’ abilities to function in extreme environments similar to those on the space station.

As part of his training the former British Army helicopter test pilot completed winter survival training in Russia to prepare for the harsh climates of space.

He spent 12 days underwater off the coast of Florida and has been practising spacewalks in a Russia Orlan spacesuit.

Despite the gruelling training and extreme conditions in space, Mr Peake said he was more concerned about leaving his wife Rebecca and their sons at home for so long.

He said: “I think my future career is probably far safer than my past career. I’ve carried out some fairly high risk flight tests. I’m not overly apprehensive.

“As a former test pilot, I believe that knowledge is gained when we explore the boundaries of what is technically and humanly possible.”

Francesco Sauro, Mr Peake’s exploration instructor, said: “Caves is an exploration mission, and this year will be more difficult as the astronauts venture further from base camp.”