By Jo Twist
BBC News Online science and technology staff
For more than 20 years, American businessman Burt Rutan has been behind some of the oddest and most innovative planes around.
Burt Rutan: A man with high ambitions
In the US, he is considered by some experts to be a national treasure, one of the few creative pioneers who has made a real difference to aerospace advancement.
When the US government wanted to test a fairly high-risk engine concept recently, Rutan wanted to be the test pilot.
He was only prevented from doing so because the government did not want to run the risk of losing him. That is how much of a precious commodity he is considered to be.
It is his company - Scaled Composites - which is responsible for SpaceShipOne, the winner of the Ansari X-prize.
Tourism on the edge
SpaceShipOne and its airborne launcher, White Knight, are widely considered to be the most promising, recyclable and efficient uses of advanced aerospace technology seen in recent years.
Scaled Composites is also behind the design of Steve Fossett's Virgin GlobalFlyer, the plane in which the adventurer will soon attempt to fly solo around the world without re-fuelling and in record time.
Craft like SpaceShipOne could be a platform for science
The current mark was set in 1986 in another Rutan creation called Voyager, piloted by his brother, Dick, and fellow aviator Jeanna Yeager. They did it in nine days, three minutes and 44 seconds.
But the 61-year-old's ambitions go further than flights of fancy around the globe, however. He wants to realise the idea of taking tourists to the edge of space and back.
His would not exactly be a budget airline into orbit - the passengers would be very rich tourists - but it would be a substantially cheaper way of getting above the Earth than current technologies.
'A real leap'
Rutan's dreams started simply. After seven years as a flight-test project engineer for the US Air Force, he opened up shop in California's Mojave Desert in the form of the Rutan Aircraft Factory (RAF).
There he built light-weight craft until, in 1982, his flight vision came into focus and he set up Scaled Composites of which he remains CEO.
Behind the company is heavy-weight funding from former Microsoft co-founder and billionaire Paul Allen.
Fed up of waiting for someone else to take him to space, Rutan took a DIY approach and started his own private space programme.
In the depths of the desert, he secretly developed SpaceShipOne at an estimated cost of $20m (£12.4m) and its airborne launcher, the White Knight.
It is White Knight's development that has really demonstrated the potential for low-cost space travel, says Professor Ann Karagozian, head of the Combustion Research Lab at University of California-Los Angeles (UCLA).
She describes Rutan's achievements as "monumental".
What makes his work different is that, instead of expensive launches of space rockets from the ground, a single aircraft takes off, flies to the required altitude and releases the spacecraft to continue the journey upwards.
It is a stable concept, says Professor Karagozian; there are no external fuel tanks that separate and fall into the ocean as with the space shuttle.
"It is really unheard-of in my opinion," she said. "It is a real technological leap and the fact he has done it in basically two years, starting from scratch, is really very novel.
"This could well be the technological concept that pushes us over the edge into the low-cost space travel arena."
Safe and robust?
The technology Rutan uses in his vehicle has been built on and developed over many years in the US, says Professor Karagozian. The difference is, he is using it in a much more efficient way.
"If he demonstrates it as a robust and safe system, then there are plenty of people who would enjoy that kind of trip to the edge of space," Professor Karagozian thinks. "But scientifically, there are lots of experiments to be done in micro-gravity."
Space tourism in 5 years?
As a former member of Nasa's Aero-Space Technology Advisory Committee and a member of various high-level strategic committees, including the National Science Foundation, this prospect appeals to Professor Karagozian.
In the aftermath of the Columbia space shuttle disaster, getting into space has been turned into a very difficult issue.
To date, most micro-gravity experiments have been done in drop towers, in which an experiment is released from the top of a very high tower to re-create weightless conditions. Nasa has these facilities but the effect only lasts a few seconds.
"Columbia's last mission was to conduct a great many combustion experiments in micro-gravity," explains Professor Karagozian.
"Many are proposing they could be done on the ISS [International Space Station] but this kind of concept could also be an alternative micro-gravity test bed."
SpaceShipOne, she says, would be cheaper than using space shuttles and, depending on how the dollars are counted, could provide a potentially cheaper way of doing the experiments than on the ISS.
"In many ways, [Rutan's] achievements in putting together these known technologies into novel and robust systems can be compared, I suppose, to what the Wright brothers did."
Of course, Rutan is not the only one working on low-cost space travel concepts but no one else is quite as far along in terms of their overall space tourism viability.
Cheap space access concepts could eventually open the door to other countries for satellite launches, Professor Karagozian says.