BBC地平线：太空旅游

Over 40 years ago man first went into space. Ever since ordinary people have dreamt of getting there themselves. But after several false starts, a group of space obsessed entrepreneurs believe the first commercial flights into the final frontier are only a few years away.
　　The concept of space tourism is not new. Following the enormous achievements made by the Americans and Russians during the 1960s many of us assumed that it was only a matter of time before it was the turn of tourists. These dreams were fuelled even further when the era's new celebrities – the astronauts – returned with tales of life-changing experiences. Space fever was so intense that by 1969 Pan-Am, one of the world's most respected airlines, opened a waiting list for a moon shuttle. It was only a concept on a drawing board but almost 100,000 people signed up.
　　The problem was that going to space was incredibly expensive. The vehicles being sent into space were only used once so every time a rocket lifted off millions of dollars effectively went up in flames. In order for space tourism to become a reality, that needed to change.
　　Budding space tourists were certain that the space shuttle was the answer to their dreams. It was reusable and capable of making several trips a year. Even the commercial world was inspired by the shuttle and in 1985 a California company started offering trips to space on a craft that would be ready for lift off in 1992.
　　In 1986 a civilian finally made it onto the launch pad when NASA put school teacher Christa McAuliffe on board the shuttle Challenger. But just over a minute into the mission Challenger exploded and the entire crew was killed. The accident had an immediate impact. Commercial ventures were cancelled.
　　It wasn't until ten years later that the dream of space tourism was revived by space entrepreneur Peter Diamandis. Convinced that it was the job of the commercial world to open the space frontier for the masses, Diamandis established the X Prize. The prize would eventually offer $10 million for the first craft to make it to sub orbital space – 62 miles above the earth – twice in 14 days.
　　The race attracted over 20 competitors. The first person to join up was Burt Rutan, one of the world's most prolific aircraft designers.
　　There was also Chuck Lauer, a former property developer who had co-founded Rocketplane Ltd. Rocketplane's approach was to build a spaceship by modifying a Lear Jet.
　　John Carmack, a 34 year-old computer games millionaire, signed up with his company Armadillo Aerospace. Carmack and his crew of volunteers only worked part-time but were attempting to build a vertical take-off and landing vehicle from scratch.
　　Most of the entrants had big ideas, but little money or concrete plans.
　　Burt Rutan decided to spend the first few years working in secret on his project. He eventually came up with a design he was certain could do the job, especially as it addressed two of the most dangerous aspects of space flight, lift-off and re-entry.
　　To avoid the dangers of a ground launch, which uses tons of highly explosive fuel, Rutan designed a carrier aeroplane that would carry his craft, SpaceShipOne, to 47,000 feet