Space shuttle Atlantis has launched from the US Kennedy Space Center in Florida, the first mission of 2007.
The shuttle took off in clear weather. It reached orbit less than nine minutes after lift-off, Nasa said.
The seven astronauts aboard Atlantis will fly to the International Space Station to continue installation work, including a new pair of solar panels.
In February, hail damage cancelled a planned March launch. Nasa's last space shuttle mission was in December.
Shuttle program manager Wayne Hale said some foam fell off the fuel tank as Atlantis headed for orbit, but added that it should not pose a risk and preliminary analysis showed it did not strike the shuttle.
"The tank performed magnificently, despite having several thousand repairs to it," Mr Hale said. "[The debris] should not be a hazard that late in the flight."
Crew will check for damage to the shuttle's heat panels later on Saturday.
In 2003, the shuttle Columbia was hit by a piece of foam during launch. Wing damage from the foam caused the shuttle to disintegrate as it returned to earth, killing all seven crew.
The Atlantis mission will lay the groundwork - and the power lines - for Europe's Columbus module to join the International Space Station later this year.
"Everything continuing to go very smoothly," a Nasa commentator said three minutes into the flight.
Nasa had hoped to be launching its second flight of the year by now, but an unusual storm passed over the Florida launch site in late February and dropped large hailstones on the shuttle, delaying the mid-March flight.
Atlantis was at the launch pad when technicians found more than 4,200 gouges from hail strikes in the external fuel tank's foam insulation.
The tank was repaired, but Nasa had to give up three months in a tight schedule to finish space station construction before the shuttle fleet is retired in three years.
"It took us a while to get to this point, but the ship is in great shape," Nasa launch director Mike Leinbach said.
Despite the delays, managers are confident they will be able to complete the station before the shuttles' 2010 retirement date.
Nasa plans to fly 15 more missions to the station to deliver large components, spare parts and other supplies. In addition, one final servicing call to the Hubble Space Telescope is planned for September 2008.
Before completion, the station is expected to be able to support six resident crewmembers - twice as many as now.
Atlantis' crew includes commander Frederick Sturckow, pilot Lee Archambault, lead spacewalker James Reilly, Pat Forrester, John "Danny" Olivas, Steven Swanson and Clayton Anderson.
Cdr Sturckow has two previous spaceflights and Col Forrester has one.
Mr Anderson will not be coming home with the Atlantis astronauts.
His job is to replace Nasa astronaut Sunita Williams, who has been aboard the space station since December. She will return with the Atlantis astronauts.