In what may be an inspired piece of publicity, a Russian pop group is undertaking medical tests with a view to travelling into space.

In between concerts, members of Na-Na are paying for the medical tests themselves.

If the outcome of the tests is beneficial, the group may begin training for a space flight with the Russian Aviation and Space Agency.

A famous precedent has already been set by pioneering space tourist Dennis Tito, who paid $20m (�14m) for an eight-day holiday in space.

Na-Na were part of the welcoming committee in Kazakhstan when he touched down on 6 May 2001.

Controversial

The cash-strapped Russian Aviation and Space Agency began offering flights aboard its spacecraft, brokered by a US travel agency, in order to raise funds for its space programme.

Millionaire Dennis Tito was the first to sign up. Tito's former employer Nasa objected to the trip on safety grounds.

But international space officials finally agreed that Tito could fly, subject to him signing a deal relieving all national space agencies of responsibility in the event of a tragedy.

Tito was the 415th person in space, and the first to pay for a trip into space, but not the first civilian to make the long journey.

Tragedy

One of Nasa's early attempts to put a non-professional in space ended in disaster when teacher Christa McAuliffe and the crew she was flying with were killed in the Challenger explosion in 1986.

Other civilians include confectionery scientist Helen Sharman, who in 1991 beat thousands to become Britain's first astronaut, a Japanese journalist and a member of the Saudi royal family, who both went to Mir.

Anyone who wants to fly into space, and has the financial resources to do so, has to set long term goals. "Have patience, set the goal, even if it takes, two, three, four, five or even 10 years," said Mr Tito.

"Set the goal and you will get there in the end."

Na-Na are not the first pop group to be involved in outer space. British band Blur recorded a song which will be beamed back from the unmanned UK space probe Beagle 2 when it lands on the red planet in 2003.

If Na-Na ever do make it into space, we may be able to watch the first ever zero-gravity concert.