CAPE CANAVERAL, Fla. The space shuttle Endeavor blasted off toward the International Space Station on Thursday, carrying a huge robotic arm that will extend the reach of astronauts building the $95 billion orbiting laboratory, Reuter reported.

Endeavor left launch pad 39A at Kennedy Space Center exactly on schedule at 2:40 p.m. EDT (1840 GMT), well within its brief five-minute launch window. The last hours of the countdown were free of complications, and the shuttle lifted off under fair skies, with a light wind and pleasant temperatures.

"It looks like a beautiful day to take the Canadarm2 and the Raffaello into orbit, so good luck and have fun on the International Space Station," Endeavor launch Director Mike Leinbach told the shuttle's seven-member crew in the final minutes before liftoff.

Canadarm2 is the monster robotic arm provided by Canada that is expected to work as a construction crane on the orbiting station, and Raffaello is a bus-sized cargo carrier provided by Italy, the two main payloads of Endeavor's mission.

Endeavor's crew is being billed as the most international of any shuttle mission, with four Americans, one Russian, one Italian and one Canadian aboard.

Canadian Chris Hadfield will be instrumental in installing Canadarm2, a $900 million, 58-foot-long (17.6 meter) robotic arm designed to move much as a pair of human arms might -- if human arms were able to move independently from a human body and carry tons of material in space.

The Italian-built Raffaello logistics module, nicknamed "Ralph," will drop off research supplies and experiments and leave the space station when Endeavor does, in about a week.

Pinpoint Timing for Endeavor

Endeavor's pinpoint timing was an advantage on this flight, because the shuttle needs to be gone from the station before April 30, when the Russian Soyuz craft is scheduled to dock there.

The Soyuz mission is essential as it is meant to exchange a new Soyuz craft, which serves as a lifeboat for the space station, with an aging one.

Endeavor's crew includes shuttle Commander Kent Rominger, pilot Jeffrey Ashby, John Phillips and Scott Parazynski -- all of the United States; Hadfield of Canada, Umberto Guidoni of Italy and Yuri Lonchakov of Russia.

They will be the first crew to visit the space station since the arrival of the three members of Expedition Two, who have been at the station since March 8.

Four of the five space agencies involved in building the mammoth orbiting outpost are represented on the crew. Only Japan was not represented on this flight.

Shuttles have used robot arms, also made in Canada, for years, but unlike those earlier versions, Canadarm2 will have no permanent attachment to the station.

Instead, it will be able to work its way, hand-over-hand along the station's walls, plugging into a series of power and data ports lining the station's exterior.

With seven joints and enough computer power to plan its own maneuvers, Canadarm2 will be able to lift multi-ton modules, handle delicate experiments or hunt for leaks and frayed cables. Eventually the arm will have a mini two-armed robot that can attach to the arm for delicate repair work.

Canadian to Make First Spacewalk

Installing the arm will take at least two and possibly three spacewalks by Parazynski and Hadfield, who will be the first Canadian to make a spacewalk.

April is expected to be the busiest month yet on the station, which has been in orbit since 1998. On Monday, the current crew of Yury Usachev, Susan Helms and James Voss oversaw the departure of a Russian Progress cargo ship, and on Wednesday, they crawled into their aging Soyuz and reparked it on another part of the station so there will be room for Endeavor to dock.

On April 30, the same day Endeavor is to land, the Soyuz crew that includes California millionaire Dennis Tito is expected to arrive, even though the National Aeronautics and Space Administration and other international partners on the station have objected to Tito's presence as a possibly hazardous distraction to the crew.