CAPE CANAVERAL, Fla. — Shuttle Endeavour and a crew of seven blasted into orbit today on what was to be the longest space station mission ever, a 16-day voyage to build a gangly robot and add a new room that will serve as a closet for a future lab.

The space shuttle roared from its seaside pad at 2:28 a.m., lighting up the sky for miles around as it took off on a multinational flight involving Canada and Japan.

It was a rare treat: The last time NASA launched a shuttle at nighttime was in 2006. Only about a quarter of shuttle flights have begun in darkness.

"Good luck and Godspeed, and we'll see you back here in 16 days," launch director Mike Leinbach radioed to the astronauts right before liftoff.

"Banzai," replied Endeavour's commander, Dominic Gorie, using a Japanese exclamation of joy. "God truly has blessed us with a beautiful night here, Mike, to launch, so let's light 'em up and give 'em a show."

They did. The shuttle took flight with a flash of light, giving a peach-yellow glow to the low clouds just offshore before disappearing into the darkness.

Gorie and his crew face a daunting job once they reach the international space station late Wednesday night. The astronauts will perform five spacewalks, the most ever planned during a shuttle visit.

The launching site was jammed with Canadians and Japanese representing two of the major partners in the international space station. The Canadian Space Agency supplied Dextre, the two-armed robot that was hitching a ride aboard Endeavour, while the Japanese Space Agency sent up the first part of its massive Kibo lab, a storage compartment for experiments, tools and spare parts.

Also on hand for the liftoff was a 19-member congressional delegation led by Rep. Nick Lampson, D-Texas, whose district includes Johnson Space Center in Houston. He is pushing for increased NASA funding.

For the first time since space station construction began nearly 10 years ago, all five major partners were about to own a piece of the orbiting real estate. The launch of the first section of Kibo, or Hope, finally propelled Japan into the space station action.

"With this flight I believe that we finally became a real partner of the (space station) project, not just one of the members on the list, after 20 some years of effort in the project," said Keiji Tachikawa, head of the Japanese Space agency.

Work on the space station project began in the mid-1980s, with preliminary design work for Kibo (pronounced KEE'-boh) starting in 1990. Space station construction, however, was stalled over the years for various reasons, most recently the 2003 Columbia tragedy.

The main part of the Kibo lab will fly on the next shuttle mission in May, with the final installment, a porch for outdoor experiments, going up next year.

Altogether, the Japanese Space Agency has invested about $6.7 billion in the space station program, including a Kibo control center near Tokyo.

Canada's $200 million-plus Dextre, meanwhile, is designed to eventually take over some of the more routine outdoor maintenance chores from spacewalking astronauts. Dextre, short for dexterous and pronounced like Dexter, will join the space station's Canadian-built robot arm, already in orbit for seven years.

In addition to working with their international payloads, Endeavour's astronauts will try out a caulking gun and high-tech goo on deliberately damaged shuttle thermal tile samples. The test — part of NASA's ongoing post-Columbia safety effort — should have been performed last year, but was put off because of emergency space station repairs.

Astronaut Garrett Reisman will stay behind on the space station until June, swapping places with a Frenchman who accompanied Europe's Columbus lab into orbit in February.

A Japanese astronaut is also part of Endeavour's all-male crew.

Endeavour's countdown was the smoothest in years, officials said. Shortly after liftoff, however, the astronauts had to deal with a couple of problems that ended up being minor. They got alert messages for some of their ship's steering thrusters, but it turned out to be a bad electronics card. Then the primary cooling system failed, and they had to switch to the backup.

A cursory look at the initial launch images — fewer than usual because of the nighttime launch — showed only one significant loss of debris from the external fuel tank 83 seconds into the flight. But it appeared to miss the right wing.

In any event, Endeavour will be checked thoroughly in orbit for any potential damage, standard procedure ever since the loss of Columbia because of a foam strike.

"This is just a wonderful beginning to what's going to be a long and challenging mission for us," said LeRoy Cain, a shuttle manager who gave the final "go" for launch. "But we're really looking forward to it and we're ready to go, ready to get to work on orbit."

It is the second of six planned shuttle missions this year, all but one to the space station. NASA faces a 2010 deadline for finishing the station and retiring its shuttles.