The Starship Free Enterprise. It also confirms what I wrote below about the unknown costs of regulatory compliance. If the FAA insists that vehicles designed for space tourism meet the same certification requirements as airplanes, then space tourism will be dead before it gets started.

Despite much excitement over the X prize, though, only a few of the more than 20 groups that have registered their wildly differing ideas with the prize foundation have any realistic chance of winning. Furthermore, of those few, it is unclear whether any have designs that will suit commercial operation. Jeff Greason is the CEO of XCOR Aerospace, another small firm based in Mojave, which designs, tests and builds flight hardware. He worries that the prize, with its attached conditions, may not lead to the right sort of craft being built. Prize entrants simply need two flights in close succession, and are not necessarily motivated to develop a vehicle with low operating costs.

Mr Greason's company has a prospective design for a suborbital vehicle, Xerus, that could fly a single tourist into space. That automatically disqualifies it from winning the X prize. But Xerus is designed to make money. As Dan DeLong, the firm's chief engineer, points out, it is necessary to take more than one passenger only if the cost per launch is high.

Mr Rutan, naturally, has his own ideas about what a truly commercial vehicle would look like. He seems to favour craft that would carry more people—perhaps between six and nine. He estimates that the first tickets would cost between $30,000 and $50,000. A second-generation vehicle, he speculates, might bring the cost down to between $7,000 and $12,000. That is about the price of a luxury cruise. But he has not published the costs of operating SpaceShipOne and its carrier jet aircraft White Knight, so it is difficult for his competitors (as well as everybody else) to work out what a ticket might actually cost.

A back-of-the-envelope calculation gives some idea. Mr Rutan says his highest costs are staff for the pre- and post-flight check-ups. He has a few dozen staff and, at one point, had a plan to run SpaceShipOne once a week for five months. Assuming each of his staff cost $120 an hour to employ, it would cost a minimum of $60,000 per tourist for staff alone. On top of that come the costs of fuel, compliance with regulations, depreciation and, naturally, profit. That bumps the figure up to something nearer $100,000. Fortunately, studies have shown there would be a market for flights into space even at this price. In this context it may be no coincidence that Mr Melvill, though a fit and experienced test pilot, is 63. For a certain sort of retiree, a trip into space would be a desirable alternative to a cruise round the world. By picking Mr Melvill to fly SpaceShipOne, Mr Rutan has given America's elderly rich a subtle reminder that space could be for them, too.

Indeed, Space Adventures, a firm based in Arlington, Virginia, which has already brokered three tourist trips on Russian rockets to the International Space Station, is promising customers a trip on the first vehicle that goes into commercial operation. It has set a ticket price of $100,000, and has sizeable deposits for 100 trips. XCOR certainly believes Xerus could operate commercially at this price.

The big unknown (and one that is bothering potential investors) is the cost of compliance with government regulations. If a spacecraft cost the same as an aircraft to certify (several hundred million dollars), the industry would not get off the ground. Aircraft companies can spread the cost of certification over many units. That would not be true (at least at the beginning) for spacecraft manufacturers. Government inspection has already, according to XCOR, added three years to the Xerus project.

Mr Rutan will not say whether he is going to try to build a craft that will take paying customers, though several reports have suggested he is putting together a business plan to do this. Mr Allen confirms that he is interested in investing in commercial operations, but says he has not reached a decision. Other wealthy entrepreneurs, such as Dennis Tito (the first of the tourists taken up by the Russians) and Sir Richard Branson (proprietor of the Virgin Group), who have expressed an interest in commercial space ventures, turned up to the launch of SpaceShipOne. Mr Tito appears ready to make an investment in the space-tourism market as soon as the legislation under which it will be regulated is finalised. Unfortunately, a bill that would do this is currently stuck in the American Senate and may run out of time this year.