The rocket leaving from Gate 18 ...

The guide book has already been written. When the first Shuttle- load of tourists touch down on the Sea of Tranquillity, they can consult a guide to the Moon, published this year by a Californian company with the appropriate name of Moon Publications. Space tourism is here, and it's big business. Even in election year in Washington DC, the White House tour loses out in visitor interest to the Air and Space Museum. Within a mile, the tourist to the American capital can see two great early Sixties icons: the portrait of Jacqueline Kennedy Onassis hanging in the hub of government; or the tiny Mercury capsule in which John Glenn orbited the earth in 1962. Ten million people each year choose the final frontier, even though the spaceship looks more like a mis-shapen Mini than a craft capable of a trailblazing trajectory.

The pattern is repeated all over the United States. Nasa's space programme may be almost burned out in a fiery atmosphere of federal cost-cutting, but the cosmos is still drawing the crowds. The stretch of Florida's shoreline nearest to Orlando is named the Space Coast, after the Kennedy Space Center on Cape Canaveral. Even though America's most dramatic venture into space in recent years has been the celluloid re-run of Apollo XIII, the launch site for lunar expeditions draws thousands of visitors every day.

Across at Mission Control in Houston, Nasa has latched on to the commercial potential of space tourism. For decades, the Johnson Space Center displayed no more drawing power than an asteroid. In 1992, the worthy displays of moon rock in dull, museumy cabinets were replaced by Space Center Houston, a Saturn V-sized theme park based loosely on space exploration.

Attracted by the gravitational pull of profits, Nasa is converging quickly with the entertainment industry - which recognised long ago the potential of extra-planetary activities. It is no surprise that Alton Towers made its name among thrill seekers with the Black Hole, while the latest big ride at Disneyland Paris is Space Mountain. The new attraction at Universal Studios in Orlando, designed to provide momentary weightlessness, is considered well worth two hours' queuing beneath the Florida sun. Astronomy sells.

All of which suggests that space tourism could be a rising star. Supporting evidence for this can be found in Bhutan - not because this tiny Himalayan kingdom is further from the centre of the earth than most places, but because of what it tells us about trends in tourism. The King of Bhutan imposes strict limits on the number of visitors allowed to catch a glimpse of a people largely unscathed by technology, and makes tourists pay dearly for the privilege of staying in relatively primitive conditions. The result is a long queue of prospective visitors. And once you can boast "been there, done that" about all the trendy and expensive places in the world like Bhutan, the only way is up.

The idea of paying to be part of the payload has been around for as long as the American space shuttle. More than 10 years ago, a Seattle-based adventure travel company called Society Expeditions was taking deposits on space shuttle trips scheduled to coincide with the Columbus 500 celebrations in 1992. Then came the Challenger disaster. After the deaths of seven astronauts, the company put its plans on hold.

The recent expensive failure of the Ariane launch in French Guiana emphasised the inexactness of space science. But with punters willing to pay out for ever more extreme experiences, certain parts of the travel industry will start asking "Can we make money out of it?" rather than "How safe is it?". For this reason I suspect the first commercial space flights will originate in Russia, the nation where you can already, with sufficient dollars, pilot a MiG fighter. The demise of the USSR means that the space programme has to pay its way. So before too long, high-spending tourists will be flown out to the former Soviet "space city" in a remote corner of Kazakhstan to be trained as temporary cosmonauts.

How high-spending? A billion roubles (about pounds 250,000) should do nicely for a few hours of near-earth orbit. Longer stays aboard the Mir space station would cost considerably more. The basic journey will be uncomfortable in the extreme. Astronauts are not strapped down to look cool, but to help withstand g-forces that make theme park rides look tame as the rocket struggles to break free of the immediate gravitational field.

How high? You won't actually get very far for your money: 50 miles is quite sufficient to achieve a respectable orbit. This is four-and-a-bit Concorde altitudes, or one-5000th of the distance to the moon. But at least you shouldn't get your feet wet when you come back down to earth; the USSR was using ground landings for years while American missions splashed down.

What will you do when you get there? In inner space, the answer is "not much". David Bowie was right when he sang "Planet Earth is blue/And there's nothing I can do". You can look out of a small window at the planet, and definitely see the curvature of the earth. Save for the odd piece of obsolete space hardware floating past, the view will begin to pall after a while. The trouble is that as tourists we have ever more sophisticated tastes - which space cannot live up to. Space is a cultural vacuum as well as a physical one.

If the initial earnings from tourism are invested wisely, though, it is not too far-fetched to see a time when day-trippers help to fund exploration. Space starts getting interesting when you reach the Moon, and Tranquillity Base will one day be the hub of the lunar tourist trade. Neil Armstrong's one small footstep will become a cosmic shrine, while all around lead- booted visitors will gleefully make the most of minimal gravity to leap higher, faster and further - which, increasingly, seems to be the ambition of every tourist.

Until space tourism takes off, the closest that the everyday traveller can get to outer space is a trip on Concorde. The supersonic aircraft cruises at 60,000 feet, an altitude at which passengers are supposed to be able to discern the curvature of the earth. I couldn't see it, though.

Concorde first flew commercially 20 years ago, and the fleet probably has another couple of decades of life left. One reason the archaic Sixties design can be expected to endure for so long is under-use. British Airways' supersonic network, which over the years has included Bahrain, Dallas, Miami, Singapore and Washington, has shrunk to just one route - Heathrow to New York. From 31 July, the service will be cut to once-daily, meaning that the fleet of seven Concorde averages only one hour in 24 actually flying. The rest of the time, BA scratches a profit from renting out planes for day-trips. Ironically, an aircraft designed to accelerate the pace of business travel is now an aviation sideshow at the flightier end of the tourism market.

No convincing replacement for Concorde is on the drawing board, a reflection of the astronomical cost of going ever higher and faster. Aircraft manufacturers and airlines find it is much more profitable to dream up new ways of keeping air travellers entertained with inflight entertainment than to send them into orbit. Moving a few people fast, however, is not nearly so profitable as shifting them in bulk at subsonic speed - otherwise Concorde might have been a success. So Britain's putative son of Concorde, called HOTOL, is unlikely to get off the ground.

The idea is seductively simple. The Horizontal Take Off and Landing craft will behave at low altitude like an ordinary plane, but then lift its payload into orbit for a high-speed hurtle through inner space. London to Sydney would take around three hours, with no need to stop at some vacuous transit lounge.

Europe's Airbus Industrie is looking at several supersonic proposals, in conjunction with US manufacturers and Japanese interests, and may yet come up with a bigger, higher, faster replacement for Concorde. But technology may not be such an obstruction as ecology. The higher you fly, the more your environmentally incorrect impact. Concorde has a grotesque noise "footprint": Windsor Castle almost visibly shakes at around 10.40 each morning, when four Olympus engines - designed for military use - lift 100 passengers on to the fast track to New York. Soon after, a sonic boom ripples the Atlantic. Concorde's effect on the fragile atmosphere 11 miles above sea level is less easy to gauge than its noise pollution, but is likely to be significant. So scheduled supersonic travel could draw to a close when the Olympus engines are finally shut down. For a supersonic aircraft to be more than the fantastically expensive failure that Concorde has become, it would need an extensive route network - which in turn would require a large number of governments to grant permission for landing rights. It was hard enough for Concorde to secure rights in the Seventies; today, it could be impossible.

The possible environmental effects of tourism in space are difficult to assess, though the space shuttle's solid rocket boosters are suspected of contributing to pollution of the atmosphere. Tests now conducted twice a year produce 109,000 kg of hydrochloric acid and 170,000 kg of aluminium oxide during each test. NASA responds by saying that these compounds are diluted to safe levels by the wind. But this does not account for where those compounds relocate. If we do come close to a fortnight in space, we might yet find our desires frustrated by the lobbying efforts of Friends of the Moon.