The modified Boeing 747 carrying the shuttle lifted off at 8:31 a.m. for Cape Canaveral. It will make several stops — the first one in Oklahoma — to refuel during the 2,232-mile trip, which was expected to cost NASA at least $1 million.
Discovery and its seven-member crew touched down Aug. 9 at the Edwards backup landing site after a 14-day mission to service the international space station. NASA diverted the landing to California after low clouds and lightning prevented the shuttle from returning to Florida on four earlier attempts.
After landing, Discovery underwent maintenance inside a steel structure on the base two hours north of Los Angeles. Crews purged the shuttle of hazardous substances and removing fuel from the on-board tanks.
Thunderstorms late Monday forced crews to temporarily suspend preparations for the shuttle's ferry home. Technicians attached a 10,000-pound aluminum tail cone to the shuttle to eliminate drag during flight.
Discovery's homecoming has been tempered by uncertainties about the shuttle program's future. The same foam issue that doomed Columbia 2½ years ago showed up during Discovery's liftoff, prompting NASA to ground all shuttle flights until 2006 so engineers could solve the problem.
A chunk of foam insulation broke off Discovery's redesigned external fuel tank during blastoff on July 26, but unlike Columbia's case, the foam missed hitting Discovery. Columbia disintegrated over Texas, killing all seven astronauts on board, when a foam piece pierced a hole in the spacecraft's left wing during re-entry.
NASA ground crews who inspected Discovery after its return from orbit found little damage to its exterior. Technicians counted about 100 dings and divots around the shuttle's protective thermal tiles, including one-fifth that were larger than one inch. Those numbers were similar to the results of other shuttle post-landing inspections.
A preliminary inspection of the shuttle's thermal blanket under the commander's cockpit window, which looked torn from orbit, showed that it remained intact during re-entry. While the protective blanket was a bit frayed and stuck slightly outward, it did not show any scorch marks.
NASA initially worried that the thermal blanket would break loose during re-entry and strike the shuttle.
During their mission, Discovery's crew spent nine days docked to the international space station, restocking it and resupplying the crew, fixing broken equipment and hauling out trash. Discovery's astronauts also conducted intense inspections of their own shuttle for damage and tested repair techniques developed after the Columbia accident.