For those tourists who have visited every continent, or even every country, space has become the new destination. In 2001, American businessman, Dennis Tito, became the first private space adventurer and since then others have followed. US-based Space Adventures is now offering a lunar expedition for $100 million per person. "Experience the majesty and wonder of earthrise," and "explore and experience the far side of the moon," says the company's website, as if the prospect of a rocket trip around the moon is barely more extraordinary than a sunset cruise on the Nile.

Meanwhile, the British entrepreneur Sir Richard Branson has set up Virgin Galactic, which plans to offer sub-orbital space travel on a commercial basis. For $200,000, any member of the paying public will be able to join five other passengers on SpaceShipTwo for a two-hour flight reaching an altitude of 110 km. Passengers will be able to leave their seats and float in zero gravity for up to 6 minutes and, according to the press factsheet "enjoy a view of space and Earth stretching for around 160 km in every direction".

Branson promotes space tourism as a means to save the planet. At the company's press launch, he spoke of the "transforming effect" a space flight will have on the thousands who would travel with the company: "Seeing the planet from out there, surrounded by the incredibly thin layer of atmosphere, helps one to appreciate the fragility of the small portion of the planet's mass that we inhabit and the importance of protecting our Earth."

Virgin Galactic has calculated the carbon emissions for a space flight as being "approximately 60 per cent of a per passenger return commercial London-New York flight", which equates to 1.5 tonnes of CO2. Per Egstam, Managing Director of Tricorona Climate Partner, a major participant in the international carbon market, says with some understatement, that 1.5 tonnes "seems low for taking someone into space". But Branson insists that Virgin Galactic will be a force for good for the environment. A reusable spacecraft and unpowered re-entry and landing are two "environmental credentials" listed. In addition, the company has just announced that the spacecraft will be used to facilitate investigations into climate change by carrying research instruments for the US government's National Oceanic and Atmospheric Administration.

One of the first space tourists will be Professor James Lovelock, who, in a well-judged PR exercise, has been promised a free trip by Branson. "It will give me a chance to see the planet from the outside. It was that view from space that helped me see the Earth as a quasi-living entity that regulates its own composition and climate," says the scientist best known for formulating the controversial "Gaia theory". In Lovelock's view, space tourism is a valid scientific experiment that could play a part in the development of relatively low-emitting "coasting flights" to the other side of the world, ultimately replacing the present generation of jumbo jets.

According to psychologist and travel specialist Professor Robert Bor of London's Free Hospital, "Travel gives us a perspective on our place and size in the world, how and where we fit with others," he says. "It shines a light on our own lives in a way that we do not normally experience when at home. In this sense, travel is psychologically beneficial." He attributes the attraction of space travel to dissatisfaction with more simple pleasures. If we look at modern life, there is a drive to constantly work harder, so to excel and be super-successful. "Ordinary" and "comfortable" may be too mundane. The same applies to some holidays. Space travel may be the ultimate expression of this.

Will high-spending amateur astronauts come back down to Earth transformed and inspired to save our fragile planet? Maybe a CEO will cancel a logging concession. Another will invest millions in carbon capture technology. A celebrity might donate all her wealth to environmental causes. If so, might not the benefits of space tourism outweigh the environmental costs? Or would it be better for the planet if these high-flying tourists spent their $200,000 ticket money here on Earth? That can pay for a lot of good works.