Discovery rocketed aloft from the Kennedy Space Center in Florida at 7:39 a.m. PDT, sending its seven-member crew on a mission that involves a rendezvous with the International Space Station and a range of safety tests developed after the 2003 disaster.
The early stages of the flight appeared to go smoothly. The shuttle's solid rocket boosters separated on schedule two minutes after liftoff, and a newly installed digital camera beamed live photos from the spacecraft back to the ground.
NASA said that it was finally ready for Discovery's 12-day flight. During the 29 months that the shuttle fleet has been grounded, the agency has scanned shuttle panels for cracks with ultrasound and X-rays, redesigned the external tanks, added new sensors, and created a new level of bureaucratic strata focused on mission safety.
Also, a contingency plan, dubbed "Safe Haven," would permit the seven-person crew to take refuge temporarily at the International Space Station if their orbiter vehicle were critically damaged. The station is estimated to have enough air and "consumables" for between 50 days and 60 days, though it would take about a month to launch the Atlantis shuttle on a rescue mission.
Discovery was, but malfunctioning fuel sensors in the external tank pushed back the date.
Discovery's crew is scheduled to deliver a cargo container filled with supplies to the space station, perform three spacewalks, and conduct routine maintenance on the station's equipment. NASA said a "top priority" will be to inspect the Reinforced Carbon-Carbon panels on the leading edge of Discovery's wing for cracks.
In August 2003, a government review board reported that Columbia's break-up was caused by a piece of insulating foam that broke loose from the external fuel tank during the climb to orbit. That suitcase-size foam block slammed into the leading edge of the orbiter's wing--an area of the spacecraft subject to intense heat--and eventually weakened it enough to cause a breakup at an altitude of 40 miles upon re-entry.
One reason for the criticism of NASA since the Columbia disaster is that the agency was warned about lack of attention to shuttle safety. A September 2001 report by outside government auditors--about a year and a half before the loss of Columbia--had raised alarms about the shuttle fleet.
"NASA still needs to fully staff areas critical to shuttle safety," the Government Accountability Office warned at the time.
Even with NASA's prelaunch preparations for Discovery, an oversight panel reported last month that the agency still does not comply with all of the recommendations made by Columbia accident investigators two years ago.