At the moment, only Russia has a more open policy, but it seems the airlock is only open to those that have a fortune in the bank to pay for a ticket. Well done, Mr Tito.
Although the International Space Station is being built in orbit, manned missions to Mars are being planned and China is close to putting a man in space, it is still as difficult as ever to become an astronaut.
The European Space Agency (Esa) has frozen its astronaut recruitment programme, the US space agency (Nasa) is delaying the admission of its next intake of astronauts, and other countries that have astronaut programmes, such as Canada and Japan, train so few space travellers that the chances of becoming one of the lucky few are slim even if you are of the right nationality and "stuff".
At the moment, only Russia has a more open policy, but it seems the airlock is only open to those that have a fortune in the bank to pay for a ticket. Well done, Mr Tito.
So if you do have ambitions to fly more than 100 kilometres above the Earth, be warned: seats on any rocket will be very rare and you may have to wait many years before you get a turn.
The best advice for budding astronauts is to start your preparation early, do well at school, be very patient, try not to be too tall and consider becoming an American citizen and even a boy scout.
There is no doubt that Americans have the best chance of getting into orbit because, as you might expect, Nasa needs more astronauts than any other space agency.
Helps to be American
Nasa's astronaut office constantly accepts applications - but only from American citizens. British-born Michael Foale got into space with dual nationality; while he was born in England, his mother was an American.
Unfortunately, budget cuts and delays in the launch and construction of the International Space Station (ISS) mean that the current selection process has been delayed by at least 12 months.
Since 1998, the European Astronaut Corps (Eac) has been based in Cologne, Germany. As a partner on the International Space Station programme, Esa regularly gets the chance to send astronauts to participate in space missions.
Even before the corps was created, Esa regularly sent people into space. Esa astronaut Ulf Merbold went into orbit in 1983, becoming only the second western European to join the elite sky-high club.
Currently, Esa has 16 astronauts on its books - the most recent one being Italian Umberto Guidoni who was also the first European on the space station. The next Esa astronaut to go to the ISS will be Frenchwoman Claudie Andre-Deshays, in October.
Must be clever
But anyone applying any time soon to be a European astronaut is likely to be disappointed. A spokesman for the Eac said recruitment had been frozen until 2005 at the earliest.
"This is because we have enough astronauts for our missions," he said.
Once the European Columbus orbital facility is added to the ISS, there may be a need for more astronauts but they are likely to be drawn from the existing corps, he added.
In any case, before you consider sending in your application, be sure you meet the minimum qualifications. Astronauts divide into two types: pilots and mission specialists.
Pilots get to fly the shuttle and dock it with the ISS, or whatever other satellite it is being sent to service or pick up.
Typically, pilots are picked from the armed forces and only those with several thousand hours of flying time on a wide variety of aircraft are likely to be considered.
There are more mission specialists on space flights but becoming one is a formidable task. Nasa, and the other agencies echo its requirements, said the minimum educational requirement was a BA or BSc from an accredited university. As well as this, it requires post-graduate work of at least three years. Many mission specialists have PhDs.
Make your own way
Astronauts should be between 27 and 37, have blood pressure, while sitting, no greater than 140 over 90 and visual acuity no greater than 20/50 uncorrected. Applicants can be up to 1.9 m (72 inches) tall, but pilots are likely to be shorter because they can cope with high-G acceleration better.
Becoming a boy scout or a girl guide might help too, believe it or not. Nasa said that 64% of its astronauts had been involved in scouting.
Even if the numbers of astronauts needed swells in the next decade, competition is likely to be very tough. Esa had 22,000 applicants when it sought candidates for training; it tested 5,500 but selected only six.
There are alternative routes into space for those that fail to be chosen in the application process. Dennis Tito has shown one way, but not everyone has $20 million to spare to pay for the fare.
Another way, of course, is to build your own spacecraft. The X-Prize has been set up to encourage and reward amateur astronauts who are building their own rockets.
But again, this route is likely to be open only to those with deep pockets, even though the X-Prize will give $1m to anyone who makes it into space and back in their own craft.