Canadian astronaut Julie Payette and the space shuttle Endeavour crew may stay grounded this weekend if the weather doesn't co-operate.

After a month of delays stemming from hydrogen leaks, Endeavour was finally set to blast into space Saturday night.

But NASA warned Friday that the shuttle's third launch attempt could be scrapped if forecasted thunderstorms roll into the area of Cape Canaveral, Fla.

Forecasters put the likelihood of stormy weather at 60 per cent, pouring cold water on the prospect that Payette would soon join fellow Canadian astronaut Robert Thirsk at the International Space Station.

Despite the delays, Payette is a space veteran who is staying calm, according to friend and fellow astronaut Chris Hadfield.

"She's one of the experienced members of the crew," Hadfield told CTV News Channel on Friday.

"You have to accept the fact that when you've been training for years and years and years, you realize that this is just another week of training," he said, speaking from the Kennedy Space Centre in Cape Canaveral.

Hadfield first blasted into space in 1995, and six years later, became the first Canadian to complete a space walk.

"In the big picture, we don't even remember after the flight that we had a little delay before hand," he said.

"It just requires keeping your emotions in check."

Hadfield said that since Payette has already been in space, she's been providing leadership for the newer Endeavour crew members, who are no doubt nervous ahead of their first launch.

"For the un-flown guys, their entire professional career hinges of them flying ... it is the true membership card for an astronaut," he said.

Endeavour and its seven crew plan on docking with the International Space Station over a 16-day mission. The shuttle is slated to deliver a final piece for Japan's space lab.

Plus, the mission will mark the first time that two Canadians have been at space at the same time.

Thirsk is on a five-month mission at the International Space Station, where he's been working on plans to put Canadian-made robots on other planets.

"It's an amazing evolution of human capability," said Hadfield about the Canadian space summit.

"It's a historic next step for Canada, and the two of them aren't going to miss the history of it, nor are they going to miss the fun of it."

Despite the anticipation, Hadfield said that a safe launch is paramount.

"We really treat it carefully," he said.

"This is the most complicated vehicle ever built. And so it's not an easy thing to launch."

With files from The Canadian Press