The landing gear of space shuttle Discovery touched the concrete of the Kennedy Space Center's landing strip at 0914 EDT (1314 GMT) on Monday. The safe landing followed 13 busy days in space for its six crew members, whose mission has left International Space Station (ISS) ready for renewed construction.
"Thanks, it was a great mission, a really great mission and we enjoyed the entry and the landing," commander Steve Lindsey told mission control after touchdown.
For the landing, entry flight director Steve Stich decided he would have Lindsey approach the runway from the northeast instead of the southwest, in order to avoid thunderstorms that just formed south of the runway. Lindsey and pilot Mark Kelly still had to fly through a deck of clouds.
This flight was the second test flight for NASA following the Columbia accident in 2003. Since then, the space agency has worked to redesign the external fuel tank to reduce the amount of foam insulation that comes off during launch. This was what ultimately led to the destruction of Columbia. But even after a redesign, another sizable chunk of foam fell off during Discovery's launch in 2005.
This time, however, both the tank and the orbiter performed well. Once in orbit, the crew used the robot arm and a boom to check for any damage from foam and ice. They performed a second inspection near the end of the mission to look for any damage from micrometeoroids or space junk.
Their careful look at Discovery's wings and nose cap did not turn up anything substantial. "We feel very confident that Discovery's in good shape to come home," said entry flight director Steve Stich on Sunday.
In addition to testing post-Columbia fixes, the mission also fitted the ISS with new equipment and delivered a third member to the crew, European Space Agency astronaut Thomas Reiter.
There was one small glitch in the pre-landing check out. One of three Auxiliary Power Units (APUs) in Discovery's rear compartment had a small leak - about six drops per hour. The APUs power the hydraulic pump, which controls some of the systems needed for landing, such as the rudder/speed brake and the wing flaps.
Flight controllers are not sure whether the leak was hydrazine fuel or the nitrogen that is used to pressurise the fuel tank. A hydrazine leak would have been more serious than a nitrogen leak. Before the de-orbit engine firing, that APU was tested and was working fine.
Now, NASA has to get ready for another shuttle launch. Atlantis could lift-off as early as 28 August, just 40 days away.
The work done by Discovery's crew has paved the way for Atlantis' mission. Astronauts Piers Sellers and Mike Fossum spent part of their three spacewalks fixing a railcar on the station's truss. The station's robotic arm needs to be able to move along the truss on this railcar to add more segments.
Atlantis will bring up some of those segments, known as the P3 and P4 solar arrays. These will provide extra electricity to the station and allow more lab modules to eventually be brought up.
Fossum and Sellers also tested out a boom on the end of the robotic arm that could be used to carry an astronaut to inspect and repair the heat shield underneath the orbiter.
Discovery's flight was the first shuttle flight to use Global Position System (GPS) satellites to give navigational guidance with landing. It is a back-up capability to the microwave system currently used. Space shuttle Endeavour will use only the GPS system when it next flies.
Read all about the mission in our special report on the space shuttle.
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