Britain's first astronaut in more than 20 years, a 41-year-old Apache helicopter pilot called Major Tim Peake, said today that his biggest anxiety about spending six months on the International Space Station as a flight engineer was the thought of leaving his young family behind on Earth.
Despite the gruelling physical and psychological tests that he has already had to endure during the highly-competitive selection process - he was just one of six European astronauts chosen out of a field of 8,000 candidates - Major Peake admitted he has a weak spot: his wife and two young sons.
"In terms of my greatest apprehension, as a family man it is the concern that over the next three years I will be spending an awful lot of time away from them," Major Peake told journalists at a press conference at the Science Museum in London.
"And when you are on board the space station for six months you leave your family behind and you are in no position to offer them any support," he said.
However, in all other respects he said he was delighted by the decision of the European Space Agency (ESA) to choose him for the six-month mission beginning in November 2015. He will be the first British astronaut to be officially funded by the UK Government.
"It really is a true privilege to be assigned to a long-duration mission on the International Space Station. For me it feels like the high point of a long career in aviation," he said.
Asked whether he is concerned about the risks of "low-earth" orbit more than 200 miles overhead, Major Peake said these are minimal compared to those he faced in his former job as a military test pilot and helicopter instructor with the Army Air Corps.
"Actually my future career is probably far safer than my past career. I've been involved in aviation for many years as a test pilot and I've carried out some fairly high-risk flight tests," he said.
"And something that that has taught me is risk mitigation to create the safest environment you possibly can. So it is not an unfamiliar environment to be working in," he added.
As part of his extensive training, Major Peake had to live for a week in an underground cave in Sardinia and spend 12 days performing complex "zero-gravity" tasks underwater off the coast of Florida.
"My training on the American space suit will continue and I will be eligible for a space-walk at the time of the mission but it is too early to say whether there will be an opportunity," he said.
Science Minister David Willetts could not contain his joy over the decision of the European Space Agency to choose "Major Tim" for a long-haul flight on the Space Station, despite the fact that Britain contributes nothing to the agency's long-term programme of manned space flight - a one-off UK payment of Euros 20m (£17m) to the agency helped to swing the deal.
"This is a landmark moment for Britain and our reputation as a leading science nation. Not only will we have the first UK astronaut for over two decades, but Tim Peake will be the first-ever Briton to carry out ground-breaking research on the space station," Mr Willetts said.
"Tim represents the very best of British. He will become a powerful role model for the young people we need to bolster this country's science and engineering workforce," he said.
Major Peake will inspire a generation of British schoolchildren to take up science and engineering, similar to the "Apollo effect" felt in the United States following the Moon missions of the 1960s and 1970s, Mr Willetts said.
Major Peake said that Commander Chris Hadfield, the Canadian astronaut who recently returned from the space station and was a hit on U-tube, has set a high bar for all subsequent astronauts in terms of engaging the wider public through tweets and photographs from space.
"Chris Hadfield has done a fantastic job and I don't think I'll be able to top his tweet rate, but I will be tweeting from space. That is certainly a large part of what I want to achieve out of this mission to try to inspire a generation," he said.
"And before you ask, yes, I do play the guitar, but very badly. And I wouldn't inflict my singing on anybody," he added.
FAMOUS FIVE: FORMER "UK" ASTRONAUNTS
Helen Sharman, 49, a chemist working for the chocolate makers Mars, was the first Briton in space. She went to the Soviet Mir Space Station in 1991 after a sponsorship deal between the former Soviet Union and a group of private British companies. She spent nearly eight days in orbit.
Piers Sellers, 58, born and educated in Britain but became a naturalised American in 1991 which allowed him to become a US astronaut. He flew on three Shuttle missions to the space station between 2002 and 2010.
Nicholas Patrick, 48, born in Britain and educated at Cambridge University as an engineer. He flew on two Shuttle missions in 2006 and 2010 after becoming a US citizen in 1994.
Michael Foale, 56, was the first Briton to carry out a space-walk. He was born in Lincolnshire but has dual nationality thanks to a British father and American mother. He is a veteran Shuttle astronaut, flying on five missions between 1992 and 2004, thanks to his US passport.
Mark Shuttleworth, 39, a software entrepreneur and second person to pay for a low-earth orbital flight as a space tourist. Holding dual South African-British nationality, he paid $20m to spend about eight days on the International Space Station in 2002.