Final launch for space shuttle Discovery

Image 1 of 22

Space shuttle Discovery shook off months of delays with a spectacular launch this afternoon – a bittersweet moment for NASA as its most experienced spacecraft blasted into orbit for the last time.

A last-second technical scare in the Air Force tracking system forced NASA to use up literally every extra second in the launch window, but engineers scrambled to clear the issue and Discovery roared brilliantly out of sight atop twin pillars of bright flame.

"They had a hiccup in some of their command systems that they didn't understand...they talked it over and decided the configuration they were seeing was stable and they were happy with it," launch director Mike Moses explained. "We had about two seconds remaining, which is about one second more than [flight director Mike Leinbach] needed to get the job done."

"This was Discovery's way to go out. She gave us a little bit of a fit today, but it was a great launch," Leinbach added.

It was the kind of cliffhanger you'd expect for a mission that was supposed to happen last November. An engine glitch and then a fuel leak forced back-to-back delays. Then cracks appeared in the orange external tank's insulating foam, revealing more cracks in the actual tank structure underneath.

Engineers conducted unprecedented repairs out at the launch pad, but NASA eventually decided to roll the entire vehicle back to the cavernous hangar to allow for more thorough repair work around the entire circumference of the tank.

Even with those issues fixed, the mission was not without more bad luck. Spacewalker Tim Kopra was injured in a bicycle accident a month ago and had to be removed from the crew and replaced by another veteran astronaut.

But all of that faded into memory as Discovery embarked on her 39th and final flight. Since 1984, Discovery has served as NASA's workhorse of the shuttle fleet, flying more times than any other orbiter and serving as the return-to-flight vehicle after two tragedies.

"It has been bittersweet. Whenever we've achieved major milestones along the way...there tends to be a few tears," offered NASA's Stephanie Stilson, who was in charge of Discovery's preps for launch. "The team, although they're excited about the launch today, there is some sadness."

Discovery is expected to stay in space for 11 days, stocking up the orbiting outpost with supplies and delivering the last major U.S. module. After this mission, the orbiter will likely be handed over to the Smithsonian's Air and Space Museum.

The shuttle program is winding down based on a presidential directive issued in the wake of the Columbia disaster. The White House hopes that commercial companies will be able to take over the job of ferrying astronauts and supplies to the space station, freeing NASA to focus on more exploratory missions.

Space shuttle Endeavour is scheduled to fly its last mission in April. NASA hopes to fly Atlantis on a final mission in June, but Congress has not allocated funds for that flight yet.