South African millionaire Mark Shuttleworth, a self-described "computer geek from Cape Town" and the second man to buy a multi-million-dollar ticket to the international space station, admits he's a bit nervous about blasting off Thursday aboard a Russian Soyuz rocket.

"A bit scared," in fact.

"The launch obviously is going to be dramatic," he told CBS Radio in a telephone interview Tuesday from the Baikonur Cosmodrome in Kazakstan. "It's 526 seconds of high explosives, a controlled explosion, 40 meters below me. I don't think there's any way that that cannot be a complete adrenalin rush.

"It's going to be hard to stay focused and to make sure we do everything we've been trained to do because the sheer exhilaration getting up there is going to be extraordinary. The Soyuz is apparently quite a ride. So I'm looking forward to that."

The Russian Soyuz rocket on the launch pad for Thursday's liftoff. Photo: Energia

At the same time, the 28-year-old entrepreneur-turned-space tourist says he's "kind of sad that the training has come to an end."

"Living in Star City was just an extraordinary experience and it's a little bit sad to me that the start of the flight is the end of the preparations and I'm going to miss that life and those people tremendously," he said. "So it's a great mix of emotions. Of course, one thinks about life in its broadest sense and all I can say is I'm ready for whatever life throws at us Thursday."

Shuttleworth, Soyuz commander Yuri Gidzenko and Italian astronaut Roberto Vittori are scheduled to blast off from Baikonur at 2:26 a.m. EDT Thursday. If all goes well, the cramped capsule will dock at an Earth-facing port on the international space station's Zarya module around 4 a.m. Saturday.

They will be welcomed aboard by the station's fourth full-time crew, Expedition 4 commander Yury Onufrienko, Daniel Bursch and Carl Walz. Onufrienko and his crewmates were launched aboard a shuttle in December and as of Wednesday, had spent 139 days in space. If all goes well, they will return to Earth in June after six months in orbit.

From left: Shuttleworth, Gidzenko and Vittori. Photo: Energia

Gidzenko, Vittori and Shuttleworth are delivering a fresh three-seat Soyuz to the station to replace its current lifeboat. Russian Soyuz capsules are certified for six months in space and the spacecraft currently docked to the outpost is nearing the end of its orbital lifetime.

After an eight-day stay aboard the space station, Gidzenko and his "taxi" crew will return to Earth aboard the lab's older Soyuz.

Vittori, a professional European Space Agency astronaut who hopes to join a future expedition to the station, is on board the Soyuz taxi mission as part of a commercial contract between the Italian Space Agency and the Russians.

Shuttleworth, on the other hand, is not a professional astronaut, scientist or aerospace engineer. He's an internet entrepreneur and science fiction fan who paid the Russians somewhere around $20 million to fulfill a lifelong dream of flying in space.

"Spaceflight has always been almost the ultimate dream for me and in a way, I always kind of imagined it would become a reality," he said from Baikonur. "I just didn't think it would become a reality on this basis. I'm convinced in our lifetimes we'll see dramatic advances in technology that make spaceflight accessible to everybody. And so I couldn't really wait for that day to come.

"But it's an even greater privilege not just to experience it as a passenger, but to be able to train with these extraordinary people who do this for a living and to use the same technology that's been sending people into space since the 1960s. I never thought that I would, not just experience space, but that I would experience it on a rocket, in a capsule with all off those tremendous forces and challenges."

American millionaire Dennis Tito became the first space tourist in April 2001 when he joined an earlier taxi crew. NASA protested his inclusion, saying the station's international partners had not yet agreed on training requirements for civilian visitors.

NASA managers went on national television, arguing Tito represented, at best, a distraction for the station's full-time crew at a critical point in station assembly and at worse, a safety threat.

Dennis Tito waves for the camera before departing on his orbital adventure. Photo: Anatoly Zak/Spaceflight Now

But in the end it was a moot point. NASA lost the PR battle and finally gave in when it became obvious the Russians were going to launch Tito whether the U.S. agency approved or not.

Since then, protocols governing training and medical requirements for non-professional station visitors, including space tourists, were finally signed and Shuttleworth, unlike Tito, was welcomed at the Johnson Space Center in Houston for training on U.S. systems.

"One of the things I wanted to achieve was to show that private interests and public agencies could work to together and that that relationship could not just be cordial but actually could be constructive," he said. "While I was very apprehensive, I must say that my entire experience with NASA has been exactly that.

"I think it's been helped by the fact that I hold very similar values as the people at NASA. I believe that exploration of space is very important for mankind. I think space provides a unique platform for specific kinds of science and in particular for inspiration and education. Because we're speaking the same language, in a sense, it's been a lot easier perhaps for me to build a constructive relationship with NASA.

Shuttleworth said NASA has made a "strong commitment to embracing what some people would say is the inevitable."

"Hopefully, they will see some fruit from their labors with me and I certainly do appreciate the help they've given us in terms of access to educational materials and the fact that we've actually reached a formal relationship which makes me a real member of the crew on both the Russian and American segments."

Unlike Tito, Shuttleworth is not merely a tourist who plans to film a few commercials and take pictures. The South African enlisted scientists to design a trio of experiments that he will carry out aboard the station, including one project devoted to AIDS.

He also plans to chat with South African school kids via ham radio, to photograph South African landmarks and he is supporting a major education initiative on the ground.

"I do hope this flight of mine (will) bring technology back to the forefront, make it a subject of discussion around the breakfast table at home and if in that way it does inspire kids to think about math and science as exciting and opening up possibilities for themselves, I'd be over the moon, so to speak."

Shuttleworth has a fit-check of his spacesuit and individual seat liner. Photo: Energia

But Shuttleworth has had to put his money where his mouth is. The addition of scientific experiments and educational activities presumably drove up the cost of his trip. But under his contract with the Russians, he said he cannot disclose exactly how much he paid.

When pressed, however, he said $20 million was the "starting point" for his negotiations.

"At the end of the day, it's a long and complicated negotiating process," he said. "In my case, I wanted to achieve quite a bit more than simply sitting in the seat and so we had to factor in the science program and other work that we've done together with the Russians.

"But the flip side was that I was very fortunate that there wasn't anybody else bidding against me, as it were. So while I can't disclose the figure, I'd say I was very, very satisfied that it was reasonable and certainly in the ball park of what other space agencies have paid to fly their astronauts and run their programs."

His research and education programs are impressive even by NASA standards, and the crew of the space station plans to welcome Shuttleworth aboard with open arms. While Tito was not allowed in U.S. modules without astronaut supervision, Shuttleworth will pretty much have the run of the place.

"I don't anticipate doing any baby sitting," Bursch told CBS News in a recent interview. "Anybody who's been as successful as Mark Shuttleworth probably doesn't need baby sitting. His plan, from what I've heard, seems pretty aggressive as far as what he wants to accomplish. He has some definite goals, some science objectives. ... I'm looking forward to their visit and it'll be interesting to see how he operates up here. We'll help out as much as we can."

Said Shuttleworth: "I have nothing but the most profound respect for those guys. They've been working flat out I think nearly five months now since December when they went up. I know they're going to be tired. We have some small gifts for them and I hope we won't take up too much of their time and that they will enjoy our visit as much as we're going to enjoy visiting their home."

Shuttleworth was born in the gold-mining town of Welkom, South Africa, While attending the University of Cape Town, he founded Thawte Consulting, an internet consulting business that ultimately became a leader in developing secure e-commerce web servers. Thawte ultimately was acquired by VeriSign.

Shuttleworth currently heads a venture capital firm called HBD, which stands for "here be dragons," and the Shuttleworth Foundation, a non-profit organization that funds educational initiatives in South Africa. He lives in London.

"I'm not an official representative of South Africa in any way, I'm not a professional cosmonaut, I wasn't selected after a grueling process and yet despite all of that, I'm very, very proud to carry the flag, not only of South Africa, but of the continent into space," he said.

"I've been really moved and touched by the reaction of people in South Africa to this. It's very important to me that South African children embrace math and science and technology at a young age because Africa needs to embrace its future. And so while this is really a personal adventure and not a national project, as it were, it moves me and I'm very touched by the wonderful support I've had from the country."

Sounding relaxed but enthusiastic, Shuttleworth gave CBS Radio an overview of his mission, saying "there are so many things that I've dreamed about that are going to be compressed into the next 10 days I think it's going to take me a year just to let the dust settle."

As soon as the Soyuz reaches orbit, he said, "we'll enter weightlessness and we enter the part where we'll be working very hard, testing the Soyuz capsule, testing the spaceship, making sure every sensor, every thruster, every pump, every valve is doing exactly what they should and that we of course have a good seal on the craft. After that, we get a chance to relax and that means I'll be looking out the window for a while and seeing the Earth for the first time from space, which is something that I've always dreamed about.

"On the third day, we dock with the station and that's going to be extraordinary. I don't think people realize what an enormous undertaking it is, not just to have such a complex piece of equipment up there but to do it as an international cooperation. Living in Star City, I can actually see the international learning that's taking place. In the short time that I've been there, the impression I've gotten is great strides are being made even though it's an incredibly difficult thing to get very different cultures, very different nationalities, very different people ... working together.

"The impression I have is this is a very important and meaningful project. To see that in action, to get the chance to work there and to get to live and work with the people whose job it is to build that station and turn it into a platform for science is going to be great."

The taxi crew during a training session in the Assembly and Testing Facility. Photo: Energia

If all goes well, Gidzenko, Vittori and Shuttleworth will strap into the station's older Soyuz and undock at 8:20 p.m. on May 4. Landing is expected about three hours later.

"The descent of the Soyuz is very intense, it's much more like an Apollo or Gemini-style descent because it's a capsule," Shuttleworth said. "So it hits the atmosphere very hard, with very intense G forces, lots of shuddering and vibration. Then hopefully, everything goes well and our parachute deploys and we have this, what they jokingly call a soft landing. So it's going to be quite a ride and my only hope is that I'll have time both to enjoy it and to do everything I've been trained to do and all the science I've got a chance to do."

Is he scared?

"Of course I'm apprehensive. There have been several days during the training when I will admit to being outright scared. I'm not a professional test pilot - I'm not a pilot! - and while those guys are used to climbing into new equipment and putting it through its paces and the risks that are associated with that, I'm a computer geek from Cape Town and this is certainly not my day job.

"But I have focused very hard on the training and I've tried to do everything that I've been asked to do. My real hope is I'll be able to perform under that pressure and be an effective member of the crew."