With a thunderousroar,Space shuttle Endeavour blasted off Wednesday night, carrying Canadian astronaut Dave Williams who was embarkingon his second shuttle trip.

Williams, who was born in Saskatoon andgrew up in Montreal,lifted off from the launching padat Cape Canaveral, Fla., at 6:36 p.m. ET for what will probably be his last space mission.

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The Canadarm will play a critical role in this mission and coming missions. ((CBC))

"They're in space," fellow Canadian astronaut Julie Payette reported for CBC News Wednesday, watching alive NASA feed that showed Endeavour make a clean separation from its external fuel tank.

"And now the work has just begun," she said, asTVbroadcast live images of Endeavour rocketing upwards and then safely entering space.

It isa historic launch for Williams, 53, who is scheduled to make three spacewalks and spend a Canadian record-breaking 19 hours outside in space, breaking the previous mark held bycolleague Chris Hadfield. He spent 14 hours and 24 minutes outside the shuttle in 2001 duringtwo spacewalks.

"I'm looking forward to getting a chance to ride on the end of the Canadarm," Williams told a press conference.

Once out in space, it will be the Canadian'sjob to add a truss to the International Space Station.

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Space Shuttle Endeavour lifts off Wednesday night, from the Kennedy Space Center in Cape Canaveral, Fla. ((Bill Sikes/Associated Press))

Williams'swife, Cathy Fraser, told CBC News she hopes her husband, who has not ridden a shuttle in nine years, will take the time to savour the moment.

"They're so busy; I really hope he gets that chance to really look and say, 'Hey, this is rare; unique. And I may not get to do it again,'" she said.

Williams last flew on a 16-day mission in 1998, as a Mission Specialist aboard the Space Shuttle Columbia.

Mission previously postponed

Previous scheduled launch dates for Endeavour have been repeatedly pushed back, with everything from bad weather to a leaky cabin to blame.

In recent weeks, NASA officials also allegeda subcontractor had intentionally sabotaged a computer aboard the shuttle, and NASA faced more public relations problems after reports claimedastronauts were drunk during past liftoffs.

On Tuesday, though, NASA test director Jeff Spaulding promised the much-anticipated launch was ready for a Wednesday mission and that NASA officials did not anticipate any issues.

"After five long years, Endeavour is poised once again on the launch pad and is ready for launch," Spaulding said. "All of our systems are in great shape and this long overdue vehicle is ready to fly."

On Wednesday morning, NASA began loading the shuttle'sexternal fuel tank with almost two million litres of liquid oxygen and hydrogen, one of the first steps in launch-day preparations that included a final shuttle inspection, cabin leak checks and air-to-ground voice checks with the astronauts.

Joining Williams on the mission is Mission Specialist Barbara Morgan, the teacher-turned-astronaut who was Christa McAuliffe's backup in 1986. McAuliffe was killed along with six others whenthe shuttle Challenger broke up shortly after liftoff.

U.S. First Lady Laura Bush called Morgan to offer congratulations "one school teacher to another," and to say thank youfor her commitment to the space program and to education.

While Williams is the last Canadian astronaut officially scheduled to fly before NASA winds down the shuttle program by 2010, Canada will still have a presence in space.

Robotic hands to attach to Canadarm2

The first component of a Canadian-engineered robotic tool, called Dextre, will go to the space station on this flight.

Next year, the tool will attach to Canadarm2 in order to inspect and maintain the space station with its robotic hands, said Richard Rembala, a spokesman for Dextre's manufacturer, MDA.

"Dextre is there to alleviate the need for astronauts to go outside and repair it. So we can use Dextre in conjunction with Canadarm2 to go out and replace, remove and install brand new electronic boxes," Rembala said.