He has trekked Antarctica in search of meteorites, dived to the Titanic in a submarine, paddled down the Amazon, soared to the upper atmosphere in a fighter jet at twice the speed of sound, scaled mountains and thrown himself out of a hot-air balloon flying as high as a passenger airline.

For Richard Garriott, 47, the son of a Nasa astronaut, the Final Frontier has been off limits — until now.

At the age of 12 Mr Garriott was told that his poor eyesight would disqualify him from following his father, Owen, into space. So the British-born computer games tycoon spent the next 35 years charting an alternative route to the stars.

In October he will become the first second-generation American astronaut after signing a deal with the Russian space agency for a seat on the Soyuz capsule, headed for the International Space Station. It will cost him $30 million (£15 million) for the ten-day trip.

“It's wiped out the bulk of my wealth, but this is a goal I've been working towards all my adult life,” he told The Times during a trip to Nasa's Johnson Space Centre in Houston, on a break from training in Russia.

Mr Garriott will be the sixth commercial space tourist, although he objected to the term because it ignored the hard science, commercial research and educational activities that he will undertake in space, including a schools project in liaison with the British National Space Centre. “I'm frankly going just because I want to go. However, I don't just want to go and look; I want to learn and study and share,” he said.

He has fulfilled his ultimate fantasy by being the ultimate fantasist; he is known as one of the all-time “game gods” in the computer world as the creator of Ultima, a bestselling video game series.

Born to American parents, he left Britain aged two months and was raised in the US. His Texas home has its own observatory, dungeons, secret passageways and hidden doorways that slide open when a ceramic talisman is waved over a sensor.

It is home to a collection of artefacts that would make Indiana Jones envious: suits of armour, fossils, a 17th-century vampire-slaying kit, a 5,000-year-old mummified Egyptian falcon and a Soviet Sputnik satellite that he brought into the country labelled as a salad bowl to avoid questions at Customs.

Among his most prized possessions — not that he will ever see it despite having paid $68,000 for it at a Sotheby's auction — is a Russian lunar rover, known as Lunakhod. It is parked on the Moon.

His curiosity for space was inevitable for a child who grew up in the elite astronaut community of Houston. His neighbours on both sides were astronauts and his father went into orbit twice.

“I would describe my dad in all seriousness as Spock from Star Trek — very articulate, calm, rational, dispassionate. Friends would come up and say, 'Wow, your dad's an astronaut, what was it like to be in space?' and I would think, 'That's a point, he never told me'.

“So I would ask him ... and he would say, 'Well, you know, it was nominal' [Nasa-speak for as expected]. I think in many ways he thought it would be bragging, or just that it made him uncomfortable to seem excited.”

It is not only his family heritage that has earned Mr Garriott respect within the space community. He has been involved in, and has invested in, adventure travel companies including Space Adventures and Zero-G, and helped to finance the X-Prize Foundation, which sets space technology competitions.

“I get criticised even though I'm spending my own money. People will always say there are far better things to spend it on. But to go over the next horizon is the only way mankind has found the things it has,” he said.

His training at Star City, outside Moscow, has tested his body to the limits. Since the start of the year he has gone through a punishing programme that has included being spun in a centrifuge to replicate the heavy gravitational forces during launch and re-entry — he is proud to say that he was not sick once — and flying in a nose-diving aircraft to achieve zero gravity.

Then there was survival training in the Black Sea, lest the Soyuz should splash down in water.

The last two Soyuz re-entries bringing crews back from the space station have gone a little awry, subjecting occupants to forces up to 9G — nine times the gravitational pull of Earth. “Even at 6 to 7G — in effect when you have six to seven times your own weight lying on top of your chest — breathing becomes a problem,” he said.

Since the day an optometrist shattered his boyhood dream with the words, “I'm sorry, but you'll never be a Nasa astronaut”, his life has been dedicated to solving the problem.

“As a kid it was like I was in a club, that everyone wanted to go to space. I just assumed it was normal,” he said. “Then all of a sudden it was like, by the way Richard, you're never going to be in that club. Yeah? Well, look at me now.”

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