The Space Shuttle Discovery is in orbit after a picture-perfect launch Tuesday, the first-ever shuttle mission to lift off on America's Independence Day holiday.

After two cancellations due to poor weather conditions, Discovery rocketed away from Cape Canaveral, Florida under near-cloudless skies for a 12-day mission.

Headed by Commander Steven Lindsay, Discovery's seven-member crew, will visit the International Space Station Thursday to deliver supplies and equipment, and to evaluate safety procedures. At least two spacewalks are planned. One crewmember, Mission Specialist Thomas Reiter of Germany, will remain on the space station for a six-month stint.

The launch went forward despite concerns stemming from a small crack that was discovered in the foam insulating Discovery's mammoth external fuel tank. It was a chunk of foam that broke off of the Space Shuttle Columbia during a 2003 lift-off that was blamed for the orbiter breaking up upon reentry to the Earth's atmosphere, killing all seven crewmembers.

Prior to lift off, NASA officials said the foam crack on Discovery was meticulously inspected, and they did not believe it posed a danger. Initial reports after the launch indicated no major problems with the insulation or any other components or systems.

Even so, NASA Space Shuttle Program Manager Wayne Hale acknowledged that some particles did fall away from the orbiter during lift-off. "What we saw happened after the time that we are concerned about debris coming off. And that is really good news," he said.

NASA officials explained that, as the shuttle rises during a launch, the atmosphere becomes thinner and particles that fall away are no longer accelerated to a speed that can cause damage to the shuttle. That out-of-danger point is reached about two minutes after initial lift-off.

NASA may opt to extend the mission to a 13th day, with a final decision on the orbiter's return date expected by Thursday.

This is Discovery's 32nd mission, the 115th overall for the space shuttle program, and the second since the Columbia disaster. The shuttle fleet is scheduled to be retired in 2010.