Dafydd Williams will be making three space walks on the mission

Dafydd Rhys Williams, whose father was from the valleys town of Bargoed, has already spoken Welsh in space and taken Gareth Edwards' rugby cap into orbit.

Weeks away from his second trip on the space shuttle, Dr Williams told BBC Wales that a Welsh dragon would be watching over his mission notebook.

The 14-day tour will see Dr Williams make three space walks.

The former emergency room physician will be helping to build an extension on the international space station on the mission, which blasts off from the Kennedy Space Centre in Florida, USA on the shuttle Endeavour on 7 August.

Dr Williams is excited by his latest challenge, which is vastly different from his role aboard Columbia in 1998 when he carried out experiments in space as a neuro-scientist.

I realised that in 30 seconds I was going to have 7,000,000lb of thrust beneath me and that kind of got my attention Dafydd Rhys Williams

"I'm not really feeling nervous at the moment, it is more a sense of excitement as all of our training is beginning to come together," said Dr Williams, who is 53 and a father-of-two.

"The last time I flew in space I was kind of the same way.

"Up until about 30 seconds prior to lift off and then, as I was looking out of the windows of the space shuttle, I realised that in 30 seconds I was going to have 7,000,000lb of thrust beneath me and that kind of got my attention!"

Dr Williams' second mission was due to have taken place in November 2003, again aboard Columbia.

But all space shuttle missions were put on hold until May 2006 by Nasa in February 2003 when Columbia burnt up on re-entry to earth.

Dr Williams lost close friends and classmates in the tragedy, but has said it would not stop him from going back into space.

His late father Bill was born and grew up in south Wales before moving to Canada when he was about 30.

But he remained proud of his Welsh heritage and passed this onto his son, who took the Welsh flag with him on his first space mission.

A Welsh rugby cap floated in orbit on Dr Williams' first mission

Dr Williams is hoping to return that flag to Wales when he touches down from his mission on Endeavour.

There are plans for him to tour schools and colleges in Wales in the autumn when he will talk about his experiences in space.

"I want to captivate the minds of students growing up in Wales who may dream of being an astronaut as well," he said.

"When I was growing up in Canada, the Canadian space programme did not exist other than to send up satellites into space.

"But lo and behold, years later Canada is one of the space exploring nations in the world, so don't think your dreams are impossible."

The Canadian Space Agency selected Dr Williams, a native of Saskatoon, Saskatchewan, as an astronaut in 1992.

He began training with Nasa three years later. His career also includes participating in two missions as a crew member in the Aquarius underwater research facility off the Florida coast.

In 2006, Dr Williams was the crew commander of a mission on Aquarius dedicated to assessing new ways to deliver medical care to a remote location, as would be done in a long space flight.