Mild fanfare greeted this April’s news that Charles Simonyi, an author of Microsoft Office, had become the fifth civilian to visit the International Space Station. Newspapers reported on the gourmet dinner packed by his companion Martha Stewart, and Bill Gates expressed interest in taking the next whirl. But as Simonyi savored weightless flight, back on Earth some were wondering—can space tourism ever be more than an intense hobby for the exceedingly rich?

Peter Diamandis, co-founder and director of Space Adventures, the company that brokered Simonyi’s trip, thinks it can. He forecasts a day when flights such as Simonyi’s cost not $20 million, but $10,000. “We’re starting to change the paradigm, which previously was that space flight was only for government astronauts,” he says. “There are thousands of millionaires who desire and could afford space flight. The question is, how do you tap that early market?”

Since his graduation from Harvard Medical School, Diamandis has created a slew of enterprises—Space Adventures, the Rocket Racing League, the Zero Gravity Corporation, the X Prize—in the quest to answer that question. Diamandis holds that a consumer-centric market of “private astronauts” could lead to everything from more efficient rocket engines to the colonization of Mars. “We need to get to the personal computer era of space, in terms of creating a volume  business,” he says.

In the push to  attract new consumers, Diamandis casts his start-ups in terms of adventure tourism and entertainment. Space Adventures offers space flight training, underwater buoyancy simulations, and tickets for a future trip to the moon (if you happen to have $100 million, you can sign up at the company’s website). At the cheaper end of the scale, only $3,500, is Zero-G, offering weightless flights on a retrofitted 727—on May 15, the company began selling tickets through the Sharper Image.

Perhaps the most blatant bid for media appeal is the Rocket Racing League, conceived as a sky-high version of NASCAR. The racing season is set to begin in 2008; governments in Dubai, Singapore, and Western Europe have expressed interest in hosting atmospheric raceways.

It is a testament to Diamandis’ passion that many of his eyebrow-raising schemes have garnered not only investors, but also profits. A dark-eyed Greek kid from the Bronx entranced by the Apollo moon landings, he was space-crazed from the age of 10. It was taken for granted that he would be a doctor like his father, but in college Diamandis pursued his space dreams with an intensity all out of proportion to a mere extracurricular. During his freshman year at MIT he plastered the campus with posters— “Student Space Enthusiasts Wanted!”—and convened the first meeting of Students for the Exploration and Development of Space, which today counts 30 chapters. Medicine beckoned, in part because he’d heard that M.D.s had a high acceptance rate to NASA’s astronaut training program.

At Harvard, Diamandis and two kindred academics launched the International Space University (ISU), a graduate institute now based in Strasbourg. In his third year, Diamandis decided to return to MIT for an aerospace degree. He later finished his medical degree at Harvard, founding a rocket company in his final year, and ultimately decided to forego residency. It was during this period that he copyrighted the poster, Peter’s Laws: The Creed of the Sociopathic Obsessive Compulsive, which included:

Perfection is Not Optional.
Do It By the Book ... But Be the Author!
When in Doubt: Think!

No wonder Diamandis needed some poster-ready guidance: During his final year of medical school, his schedule involved working the graveyard shift at the ER, sleeping five hours, and then running the rocket company for the rest of the day.

Members of the current generation of “astropreneurs,” many of them Silicon Valley billionaires, often compare the nascent space industry to the early days of the Inter­net. Diamandis has thrived on that start-up atmosphere, launching many companies from his home office. These days, his former program—Health Sciences and Technology, run jointly by Harvard and MIT—is abuzz with the possibilities of commercial space flight. Erika Wagner, a Ph.D. student specializing in space medicine, notes that private start-ups are beating out NASA as career destinations. “It’s like when the dot-coms were new,” she says. “It’s an atmosphere of high risks and high rewards.”

Of course, the dot-coms couldn’t succeed without millions of consumers connected to personal computers—and the space industry also depends on cheaper, safer flight technologies. Diamandis has been active on that front, too. Perhaps his biggest triumph to date was the 2004 debut of the Ansari X PRIZE, a high-profile competition to spur development of a reusable space shuttle—and successor, Diamandis says, to the prize that stimulated Charles Lindbergh’s trans-Atlantic flight in 1927. Richard Branson’s company Virgin Galactic is already signing up customers for future launches of SpaceShipTwo, an updated version of the vehicle that won the prize.

Private astronauts, sub-orbital vacations—where does it all lead? For Diamandis, space tourism is only a conduit to more extravagant interactions with the galaxy: land-grabs on the moon, asteroid mines, off-planet biotech experimentation. And like physicist Stephen Hawking, who rode a Zero-G flight in April and has long said that the survival of the human race depends on space colonization, Diamandis worries that humanity has all its eggs in one basket. “There’s a moral obligation to back up the biosphere, to catalogue the sum total of human knowledge, as well as the genetic diversity of life off Earth,” he says. “Should anything happen—asteroid imp­act, massive terrorist attack—it would be a bloody shame to lose most of the information that has accumulated.”