Storms scuttle Endeavour's 5th launch attempt

The space shuttle Endeavour sits idle under stormy skies at the Kennedy Space Center in Cape Canaveral, Fla., on Monday. (Scott Audette/Reuters)

Thunderstorms have scuttled NASA's fifth attempt to launch space shuttle Endeavour from the Kennedy Space Center in Florida.

Launch managers halted the countdown just minutes before Endeavour's scheduled blast-off time of 6:51 p.m. ET Monday. Forecasters had warned there was a 60 per cent chance weather would force another delay.

NASA said the next launch attempt will be delayed for 48 hours until Wednesday. After that, the mission will have to wait until July 27, so Russia can launch supplies to the space station.

NASA had to scrub four earlier launch attempts. Bad weather delayed the shuttle launch on Saturday and Sunday, and last month potentially dangerous leaks of hydrogen gas thwarted back-to-back launch attempts.

The seven astronauts, including Canadian Julie Payette, came within minutes of launching to the International Space Station on Sunday, but storms quickly moved in from the west, prompting managers to stop the countdown.

Canadian astronaut Chris Hadfield said the delay until Wednesday is needed to give the crew of Endeavour time to get refreshed after going through five launch preparations.

"These guys worked all last week here and worked through the whole weekend and now they have worked today and you can only go to the well so many times," he said.

"You need people to not make mistakes because they are tired. That's the situation we're in here now. And so that's the right call to make," Hadfield said from the space centre in Cape Canaveral, Fla.

During the 16-day mission, the astronauts are scheduled to perform five spacewalks and complete the construction of the Japan Aerospace Exploration Agency's Kibo experiment module at the space station.

Payette, Endeavour's flight engineer, will operate the Canadarm 1, the Canadarm 2 and a third mechanical arm that is to be installed on the space station.

Payette, who is making her second foray into space, was the first Canadian to visit the space station in 1999.

The mission will mark the first time two Canadians will be in space at the same time. Robert Thirsk arrived at the space station in late May aboard a Russian space capsule for a six-month stay, the first time a Canadian has participated in a long-duration mission to space.