The first space shuttle launch of 2007 went flawlessly.
"Five, four, three, two, one, and lift-off of space shuttle Atlantis to assemble the framework for the science laboratories of tomorrow," said George Diller, a NASA spokesman.
At a briefing after the lift-off of Atlantis, launch director Mike Leinbach was pleased with how things had gone.
"It was a beautiful launch. I'd forgotten how pretty they were," he said. "It's been about six months since we launched before, and it always come back to roost that they're just a beautiful sight to see a complex machine like this fly."
During the 11-day mission, the shuttle's seven astronauts will deliver two new segments to the orbiting scientific outpost and a pair of energy-producing solar panels.
Astronaut Clay Anderson will also replace astronaut Sunita Williams as the U.S. representative aboard the space station.
But the major focus during the lift off was the shuttle's external fuel tank. The insulating foam was heavily damaged by hail stones in a freak hail storm at the end of February.
The storm at Kennedy Space Center in Florida delayed the scheduled mid-March launch.
Instead of replacing the damaged tank, NASA decided to patch the thousands of dings, dents and pits to the fuel tank's insulation.
Space shuttle program director Wayne Hale said the foam that makes up the tanks' insulation held up well during take off.
"We did see some things come off late as we have come to from all our tanks," he said. "So, the tank performed in a magnificent way despite having several thousand repairs done on it, as did the rest of the system perform in an outstanding and magnificent way."
Because of delays, NASA has been forced to reduce the number of missions it planned to make to the space station this year from five to four.
The space agency is planning to fly at least 13 more construction missions to the space station before the space shuttle fleet is grounded in 2010.