But since those heady, pioneering days, space exploration has lost much of its lustre, with the science fiction worlds of TV and film taking us beyond the final frontier and leaving reality a distant speck on the horizon.

Now, though, it seems we could once again be standing on the cusp of a new and exciting era. Billionaire tycoon Sir Richard Branson recently described 2008 as the "year of the spaceship" after unveiling the designs of two Virgin Galactic craft which could help take the first tourists into space. Work on SpaceShipTwo, and its mothership White Knight Two, is nearing completion and flight tests are due to begin later this year.

Sub-orbital trips, taking six paying passengers at a time, are already planned for 2010 although a seat on one of these flights will reportedly set you back $200,000 (£107,000). This might sound astronomical, but Sir Richard says the technology behind these space planes will herald a new era and could help to "answer key questions about Earth's climate and the mysteries of the universe".

These are bold claims, but space enthusiast Jonathan Levy believes they may well be justified. "It's exciting, because whereas before the concept of ordinary people going into space was in the realms of science-fiction, Branson's investment has meant that space travel could one day be affordable."

Levy describes Sir Richard as the first "astropreneur" and believes his investment could spark a new commercial space age and reignite public interest. "When I was young I wanted to be an airline pilot because I knew I wouldn't be an astronaut, but maybe the next generation of children will say they want to be a pilot on Branson's space team."

He says that private investment is the key to future space exploration. "Because the space programme is built around government money some people see it as being built on old technology and it's taken the commercial sector to come in with new ideas to take space technology to the next level."

US businessman Dennis Tito became the first space tourist when he flew in a Russian Soyuz launcher in 2001, but he had to fork out £11m for the privilege. Virgin Galactic's planned flights last two-and-a-half hours with passengers climbing to an altitude of 68 miles, where they will experience a couple of minutes' weightlessness and can stare, for a moment, out into the vastness of space, before returning to Earth. And with 200 people already understood to have booked and another 85,000 registering an interest, there appears to be no shortage of takers.

David Ashford, director of commercial space plane design firm, Bristol Spaceplanes (BSP), thinks space tourism will soon become big business and will eventually become affordable to people like us.

"My projection is that we could have one million people going into space in the next 15 years," he says. "Once the programme gets underway costs will come down quite rapidly, perhaps down to as little as a few thousand pounds."

Ashford, whose firm is looking to develop its own sub-orbital spaceplane, the Ascender, claims the industry has suffered decades of under-funding and says it is time to end what he calls the "government's monopoly" on space exploration and research.

"If you go back to the Sixties, the expectation was that space planes would be the next step, but this didn't happen because of bureaucratic inertia."

The American X-15 rocket plane reached the edge of space more than 40 years ago during the first manned sub-orbital flights, but it is only recently that such military-based technology has become accessible to the private sector.

Virgin Galactic is among several companies hoping to offer space trips in the next few years. Amazon.com entrepreneur Jeff Bezos is spearheading a project, while Europe's EADS Astrium, the company that co-ordinates the manufacture of the Ariane 5 rocket, is developing a commercial space plane.

Sub-orbital flights give those on board a tantalising glimpse of space, but we are still some way off being able to develop passenger craft that can orbit the earth and allow us to continue our migration into the solar system. That, it seems, will be left to future generations.