But even with the flawless night landing at Edwards Air Force Base in California, the shuttle fleet will be grounded
for an undetermined length of time. That's because a piece of foam insulation broke off the shuttle's external fuel tank during the 26 July liftoff -- the same problem that doomed "Columbia" and that was supposed to have been corrected.
Mission control in Houston announced the return of "Discovery":
"Main [landing] gear touchdown. Drag [para]chute deploy. Nose gear touchdown. And 'Discovery' is home."
A few seconds later, shuttle commander Eileen Collins expressed the feelings of the crew, saying: "We're happy to be back, and we congratulate the whole team on a job well done."
Two planned landing attempts in the southeastern state of Florida were canceled earlier on 9 August because of concern about low clouds. The shuttle needs clear visibility for about 8 kilometers to ensure the spacecraft is properly aligned for landing.
After the shuttle's 26 July launch, "Discovery" spent nine days hitched to the International Space Station. In addition to resupplying the station, the "Discovery" crew also removed waste and broken equipment -- one of the main goals of the mission.
Astronauts also conducted three space walks.
Two space walks were used to replace a failed gyroscope and to restore power to another. The gyroscopes control the orientation of the station. After that work, "Discovery" commander Collins was able to confirm that all four of the station's gyroscopes were running simultaneously for the first time in three years.
"We have definitely accomplished our mission objectives," she said.
The two space walks also were used to test repair techniques for the shuttle's thermal tiles in case of damage.
And in the third space walk, astronaut Stephen Robinson put some of those techniques to the test. For the first time on a shuttle mission, he went beneath "Discovery" to gently tug out two protruding thermal-tile fillers that had apparently been damaged during liftoff. Engineers on the ground thought the material could cause overheating during re-entry and perhaps lead to another Columbia-type catastrophe.
Columbia was doomed by a large piece of insulation that broke free from the external fuel tank during launch and caused a hole to form in the ship's left wing. As Columbia re-entered the Earth's atmosphere, searing gases melted the wing from the inside, causing the ship to break apart. All seven astronauts aboard were killed.
Because of that tragedy, the shuttle's crew used cameras and lasers to inspect their ship for damage on five different days of the mission. Those inspections alerted ground controllers to the problem with the thermal tiles, which protect the craft from burning up during re-entry.
After his space walk, Robinson spoke about the significance of the repairs.
"The ability to repair goes hand in hand with the ability to inspect. We now know more about our shuttle than any crew has ever known before they came back home," Robinson said. "That's a fantastic step forward. The next step is to be able to repair any damage we happen to have found. Our shuttle didn't require any repair. Just a tiny little dental flossing -- plugging a couple of gap fillers up. But the work that the folks have done on the ground -- and the tests that we've done in orbit this time with the spacewalking -- have laid the first brick in that road. So we're pretty confident that a lot more progress will be made pretty soon."
The shuttle's mission initially had been scheduled to last 12 days. An extra day was added so the crew could transfer as many provisions as possible to the space station amid uncertainty about the date of the next shuttle flight.
The shuttle spent another extra day in orbit after concern over weather in Florida led ground controllers to cancel a landing planned for 8 August.
(compiled from agency reports)