The space shuttle Atlantis blasted off on Saturday from Cape Canaveral, Fla., with a crew of six astronauts on board, including Canadian Steve MacLean, with no apparent damage from debris.
The liftoff took place at 11:15a.m. ET through a partly cloudy sky.
"What you saw today was a flawless count, a majestic launch," NASA administrator Michael Griffin told reporters.
Atlantis, now in orbit over the Earth, is expectedto dock with the international space station on Sunday. The mission itself is expected to last 11 days.
"It feels great," MacLean's wife, Nadine, told reporters. "We are all relieved!"
Cameras focused for damage anddebris
As Atlantis soared into into space, more than 100 NASA cameras were trained on it, watching for any sign of foam breaking off the shuttle's external fuel tank.
NASA's cameras spotted three possible hits — two small foam streams and one ice chunk — but they came so late that the debris wasn't moving fast enough to do much damage, shuttle program manager Wayne Hale said.
"We are looking at nits — nothing of any remote consequence," Hale said. "Not only am I not alarmed, I'm really at ease after looking through this video."
The first and most noticeable hit was just four minutes after launch when a dribble of small foam particles hit Atlantis's right belly, but it didn't appear to cause any damage, Hale said.
A minute and a half later, more foam hit the shuttle's right side, but again with no evident damage, Hale said. And at nearly nine minutes, a small ice chunk hit near the nose gear landing door but with no apparent harm, he said.
Foam problem led to Columbiadisaster
On Feb. 1, 2003, a piece of foam came off the external fuel tank of the shuttle Columbia. The foam hit the shuttle's wing and left a hole, which led to the wing overheating as the shuttle re-entered the atmosphere. Columbia disintegrated a few minutes before it was scheduled to land, killing all seven astronauts aboard.
On Friday, NASA had to cancel a launch attempt only 45 minutes before it was scheduled to happen. Officials blamed a problem with a sensor on the large external fuel tank, which had also caused the cancellation of two other launch attempts.
Atlantis was originally set to launch on Aug. 27, but was delayed when lightning struck the space centre two days earlier. The launch was rescheduled, but had to be postponed again because of the approach of tropical storm Ernesto.
It was delayed onWednesday when a problem with the coolant system on one of the shuttle's fuel cells was found.
Finally on Saturday, Atlantis was able to lift off.
Tears and relief at Mission Control
"The countdown itself went extremely smoothly, which probably shouldn't be surprising considering how many times we tried it," said Mike Leinbach, NASA's launch director.
Leinbach said the smooth launch was something the Atlantis astronauts and ground crew have worked on for years.
"There were literally tears in the firing room. It felt excellent to reward them with this launch today," he said.
MacLean and five other astronauts have been preparing for more than four years to perform construction work on the international space station.
MacLean will operate Canadarm 2
Canadian astronaut Bjarni Tryggvason, who was on hand to comment for NASA from Cape Canaveral, told CBC News that MacLean will play a pivotal role during the Atlantis mission.
"He's going to be operating the Canadarm 2, the robotic arm on the station that Canada providedfor the space station program. He'll be the first Canadian astronaut to actually operate that arm on the space station," said Tryggvason.
"Later in the flight, after the shuttle detaches from the space station, he will be operating the arm to do the inspection of the space shuttle tiles to make sure that they're allOK for the return to Earth in about a week and a bit."
The Canadarm 2 weighs 1,640 kilograms andis 17.6 metres long when fully extended,with seven motorized joints. It's capable of handling large payloads and helping to dock the space shuttle.
It was installed on the space station in April 2001, when Chris Hadfield became the first Canadian to take a walk in space.