The space shuttle Discovery successfully lifted off from its Florida launch pad on Tuesday, carrying its seven crew members and a new habitable component to the International Space Station.

The space shuttle Discovery lifts off from launch Pad 39A at the Kennedy Space Center in Cape Canaveral, Fla., on Tuesday.
(John Raoux/Associated Press)

On Monday, the U.S. space agency had warned of the possibility of rain and low clouds, but the shuttle lifted off from NASA's Kennedy Space Center in Florida to clear skies at 11:38 a.m. ET.

While weather wasn't an issue, NASA considered delaying the launch after inspectors discovered a piece of ice on a liquid hydrogen line. The piece of ice measured at 10 centimetres long and four centimetres in diameter.

NASA was originally concerned the chunk of ice would fall off during launch and possibly damage the orbiter as it rose, but later determined the size of the ice did not pose a problem. The issue became a moot point after the ice appeared to melt in the hours leading up to the scheduled launch time.

The space agency last week decided to go ahead with the launch despite questions about small defects on heat shield panels along its wings. NASA said the degrading of the coating, while not fully understood, was an acceptable risk.

The Discovery and its crew of seven, led by shuttle commander Pamela Melroy, is scheduled to carry up a pressurized compartment — called Harmony — to the International Space Station that will act as a dock for two new laboratories.

This photo shows a close-up of the engines in early stage ignition as the shuttle launches.
(NASA)

The mission will last 14 days and will include five spacewalks. In addition to installing the Harmony node, the shuttle and space station crews will also transfer a solar array from the top of the station to its permanent position on the port side.

They will also test a thermal tile patch, one that could be used in case repairs are needed to the shuttle.

A European laboratory is scheduled for a Dec. 6 launch, while a Japanese version is set to go up in two pieces, in February and April.