Space is tourism's final frontier, and its lure has helped a dozen start-up companies raise millions of dollars for the development of cheap re-usable rockets to take high-flying trippers into orbit.
And they are just the pioneers of an extra-terrestrial tourist industry that could lead to hotels on Mars later this century, the American Association for the Advancement of Science annual meeting has been told.
Mr Yoji Kondo, an astrophysicist with NASA, said the start-ups were pinning their hopes on a variety of launch technologies.
"These entrepreneurs do not need new break-through technologies to succeed," said Mr Kondo, who monitors their activities for the US space agency.
"They are adapting existing technologies and making them far cheaper to operate than the Shuttle."
Although NASA is not directly involved in space tourism, its Xseries programme to produce a successor to the Shuttle is developing technology that will be useful for the private sector.
Each Shuttle flight requires 10,000 NASA staff and contractors to service and operate it, and the US taxpayer pays about $100 million (€102 million) per astronaut for a week-long stay in orbit.
The private-sector companies aim to cut costs to $100,000 or less per passenger for a much shorter trip of perhaps an hour or two in orbit just long enough to experience sustained weightlessness and enjoy the magical sight of earth from a couple of hundred miles up.
Their motivation is the extraordinary growth in demand for expensive adventure holidays, which leads tens of thousands of people to spend thousands of pounds travelling to Antarctica and other remote destinations every year.
Working from surveys which consistently show a huge public interest in space travel, Mr Kondo claimed 10 million Americans would be willing to pay $100,000 for a ticket into orbit.
Travel companies may be selling tickets for short orbital flights later this decade. But space tourism will not stop there.
Japanese and US companies have already designed orbital hotels for longer visits, which could be open by 2020.
And Prof Freeman Dyson of Princeton University's Institute for Advanced Studies had no doubt that wealthy people would want to visit Martian settlements, just as they are keen to taste the experience of earth orbit today.
He told the conference about his vision of hotels on Mars.
"The best approach will be to use biotechnology to grow the habitat, rather than using engineering to build it," Prof Dyson said.
