The U.S. space shuttle Discovery has landed in Florida, ending a resupply and maintenance mission to the International Space Station. Its successful flight means the space agency NASA can finally resume construction of the station.
Discovery's safe landing is an obvious relief to NASA, which was forced to halt assembly of the half-built space station more than three years ago when the shuttle Columbia disintegrated upon re-entry into the atmosphere.
Discovery, sounding like any other airplane, glided smoothly onto a runway at Kennedy Space Center.
Flight controllers greeted its six astronauts.
"Welcome back Discovery, and congratulations on a great mission," said the flight controller.
The landing concluded the first shuttle flight in one year, and only the second since Columbia's demise.
Columbia burned up when searing gases, caused by friction with the atmosphere, entered a hole in its wing. The hole was caused by hard foam insulation that broke away from the external fuel tank and hit the shuttle during launch.
NASA described Discovery's flight as a test of its three-year effort to make sure this never happened again.
It minimized the amount of debris that flies away from the fuel tanks, installed an array of ground cameras to monitor launches, and put new cameras and sensors on the orbiters to detect possible launch debris strikes or hits by micrometeoroids while in orbit. Discovery's crew found no damage during several scans of its fragile heat shield, giving NASA confidence it could bring the shuttle home safely.
The chief of the International Space Station program, Mike Suffredini, says the mission was nearly flawless.
"I cannot think of a better mission in recent history. Every objective that we went in with was completed, and, in fact, a couple of extra things got done for us that we thought, perhaps, we wouldn't have time for," he said.
The objectives included bringing a third crew member to the space station, which had only two since Columbia's accident. Discovery also hauled up new supplies and equipment to the outpost, and the astronauts took spacewalks to repair station equipment critical to resuming its construction.
"So with this flight, in our minds, we are ready to get on with assembly, and we will do just that," he said.
Space station assembly restarts late next month, when the shuttle Atlantis is scheduled to deliver a pair of solar energy panels, new batteries and a truss segment on which to mount other components.