Thirteen years after Bjarni Tryggvason blasted into space on board the space shuttle Discovery, the veteran astronaut will travel to the U.S. to witness its final flight.

And he will be watching with envy when his fellow astronauts take the leap beyond the Earth's boundaries, exploring the world of outer space.

"My thoughts are kind of always with them," Tryggvason told in a recent telephone interview from his Ontario home.

Since his own flight to space in August 1997, Tryggvason has retired from life as an astronaut and is now involved with other pursuits in the private sector.

But he has still kept a hand in the world of adventure. Last year, Tryggvason flew a replica of the Silver Dart -- the first powered plane to take flight in Canada -- over a frozen Nova Scotia bay.

Tryggvason said leaving behind his astronaut life is a choice he says he doesn't regret, because it gave him the opportunity to spend more time with his family.

But Tryggvason, now 65, admits he remains "jealous as hell" that he isn't the person leaving Earth behind every time he sees a shuttle launch, taking one of his colleagues to space.

"Every time I see the shuttle going into space…I know someone on it," he explains.

Tryggvason is one of only three Canadians who flew aboard Discovery during its 26-year service run.

The first was Roberta Bondar, who served as payload specialist on Discovery during a January 1992 NASA mission.

In a telephone interview, Bondar explained to that she was actually supposed to ride on two other shuttles before she ended up travelling on Discovery.

Bondar said she is still remembers "the feeling that we were on a mission of Discovery," and that life would be different when she entered the belly of the space orbiter and blasted off from Earth.

"You are going to be the thing that either kills me or makes me a different and better person," she said jokingly.

Bondar also recalls vividly the first time she looked down upon the Earth from inside the Discovery.

The next Canadian to ride on Discovery was Tryggvason, who went to space five-and-a-half years later. He also served as the payload specialist on the shuttle.

The last was Julie Payette, who served as the mission specialist for Discovery's trip to the International Space Station in the spring of 1999.

On those three missions, Discovery travelled a combined 1.82 million kilometres and put each Canadian in space for more than a week.

For Payette, her ride on Discovery was her first trip to space, something she describes as being "a huge deal in an astronaut's life."

After years of training, it was her chance to take the journey of a lifetime -- though in her case, Payette would return to space a decade later on board the Endeavour space shuttle a few months before her 46th birthday.

But the details of her first space-flight are firmly etched in her mind: The drive to the base of the shuttle at Kennedy Space Center. The bright Xenon lights lighting up Discovery's exterior in the early-morning hours. The experience of weightlessness.

"The spacecraft is very much alive," Payette told in a telephone interview, describing the moments before the launch of a shuttle.

Upon lift-off, Payette sat in the "exact same seat" where famed astronaut U.S. John Glenn had sat in the previous Discovery flight.

That was the flight where Glenn set a record as the oldest man to travel to space at the age of 77.

It's this kind of history that is made with each shuttle flight. Just like when Payette flew to the International Space Station on Discovery, becoming the first Canadian to step foot on board the international research lab.

But Payette is quick to point out that astronauts do not choose the shuttle they travel on, that they are fortunate to be picked for any mission, to perform any task.

"We just go out there and try to do the best job that we can," said Payette.

When Discovery launches its final flight, Payette and her Canadian colleagues will mourn the coming end of an era.

NASA is winding down the space shuttle program and Discovery will be the second-last space shuttle to launch. The last will be Endeavour, which will carry spare parts to the space station next year.

It will shift the activities of astronauts such as Payette, who have spent years learning the intricate operations of the space shuttle and the 1,800 switches in its main cockpit.

"The shuttle training is getting to an end and we concentrate now on the space station," Payette said.

Both Tryggvason and Payette told that they will be at the Kennedy Space Center for Discovery's final flight.

Tryggvason will travel to Florida from his home in Ontario, making sure to get a front-row seat for the launch.

"I'll be there in the family viewing area, because I'll be there as a guest of the crew," he said.

Payette will be travelling from Houston, where she continues to train as an astronaut.

Bondar said she'll be watching Discovery on a high-definition television at home in Canada, where the moment will be almost as special.

Though she's been to a lot of launches, Bondar said seeing people "disappear off the planet" is an extraordinary sight to see in person.

She said it is fitting that Tryggvason and Payette can both attend the last Discovery launch, representing two generations of Canadian astronauts.