Qualifications

Very rich Speaks English Good health

Disqualification

Drugs Alcohol abuse Criminal, disgraceful or infamous behaviour

The nine-page report was released as the world's second space tourist, South African internet millionaire Mark Shuttleworth, completed a week of training at the Johnson Space Center in Houston, Texas.

In the past, Nasa has resisted the idea of space tourism. It strongly opposed the trip made by the world's first space tourist, Dennis Tito, in April 2001.

But in December last year, the agency made a dramatic U-turn and gave its approval to Mr Shuttleworth's flight.

Disqualification

When Mr Tito visited the Johnson Space Center two years ago, he was banned from joining his Russian crewmates in training.

Nasa resisted Dennis Tito's flight

But now Nasa's top space station official, Michael Hawes, has acknowledged that Mr Tito's flight helped form the basis for the new criteria for deciding who could and could not go.

Under the new criteria, which took two years to prepare, having an enormous amount of money will not be enough to ensure entry to the ISS.

Candidates can be disqualified for numerous offences, including delinquency and criminal, dishonest, disgraceful or infamous conduct.

Habitual drug users or those who indulge in excessive drinking will also fail to make the grade.

As will those who have held membership or sponsorship in organisations which could damage the public's confidence in the space station or any of the space agencies involved.

Embarrassment to partners

According to Charles Precourt, Nasa's chief astronaut, who helped create the list, said each candidate would be assessed on a case-by-case basis and a person's age at the time of the offence and the surrounding circumstances would be taken into account.

Mr Shuttleworth will blast off in April

The list will be followed by the space agencies of the United States, Russia, Canada, Japan and Europe.

"We want to ensure when we nominate someone, that we don't embarrass our partners by having someone who would be so controversial that it would be an insult to the other partners to fly them," Mr Precourt said.

According to Mr Precourt, the evaluation is similar to that used by the US Government in background investigations for positions requiring security clearance.

Fitness test

Future space tourists must also be able to read and speak English, pass medical tests and will be required to undergo training both in Moscow and Houston and follow a code of conduct.

Nasa is keen to stress though that the publication of the list does not mean that it is about to start flying tourists into space itself.

Mr Shuttleworth, who is reported to have paid as much as $20m for his flight, will have to travel to the ISS in a Russian Soyuz capsule.

He had been scheduled to take off on 22 April, but now that launch has been pushed back to 27 April because of technical problems.