The space shuttle Atlantis has touched down safely in Florida, ending a 12-day mission to re-start construction of the International Space Station (ISS).
The shuttle made a perfect landing on runway 33 at Nasa's Kennedy Space Center just after 0621 EDT (1021 GMT).
"Nice to be back. It was a great team effort. Assembly is off to a good start," said Atlantis' commander Brent Jett after the landing.
The mission is the third shuttle flight since the Columbia disaster in 2003.
A planned return on Wednesday was postponed after astronauts spotted several mysterious objects floating in space outside the orbiter.
But inspections found no damage to the spacecraft from the nearby debris. And the US space agency (Nasa) was happy that none of the items posed a further risk to the vehicle.
No problem: Atlantis performed impeccably, Jett said
There have been some suggestions that the objects escaped from the shuttle's cargo bay.
The six-strong crew disembarked Atlantis just before 0800 EDT (1200 GMT) and were welcomed on the runway by Nasa administrator Michael Griffin.
"Atlantis was a terrific ship. She gave us no problems at all during the mission. And we would have had no time to fix them so it was critical she performed well and she did," commander Jett said in a brief photo-call with his crew before returning to quarters.
In a post-flight press conference, Michael Griffin was asked about the "litter problem".
"Humans are not perfect and are not perfectable," he responded. "It would cost us an awful lot in money and in operations to make sure the cargo bay is pristine. But I'm not sure that's where we want to put our resources."
He added: "In zero-G those imperfections come out".
At 0514 EDT (0914 GMT) and orbiting at a speed of 29,000km/h (18,000 mph), Atlantis had initiated a three-minute engine burn to commit the spacecraft for the trip back to Earth.
The "de-orbit" burn slowed the shuttle's velocity by about 329km/h, just enough to slip the craft out of orbit and begin the plunge through Earth's atmosphere.
On its hour-long dive back to Earth, temperatures outside the shuttle reached nearly 1,650 C (3,000F).
A cockpit's eye-view shows the nighttime landing
The space station's new commander Michael Lopez-Alegria and Nasa science officer Jeff Williams watched the re-entry from the ISS, orbiting 354km (220 miles) above Earth. They reported a bright plasma trail as Atlantis descended to Earth.
"Spectacular lightning flashes just below the orbiter," Williams said over the radio to mission control. "The glow of the orbiter itself is getting dimmer, but the contrail is still pretty bright."
During Atlantis' stay at the ISS, crew members attached new solar wings to the space station - doubling its power generating capability. The shuttle left the ISS on Sunday.
The next shuttle flight in the ISS construction sequence is set for December.
Holiday in space
On Wednesday, space tourist Anousheh Ansari and two other crew members of a Russian Soyuz spacecraft entered the space station after docking smoothly with the orbiting platform at 0121 EDT (0521 GMT).
Ms Ansari arrived at the station with Lopez-Alegria and Mikhail Tyurin - the relief crew for the ISS.
The new arrivals were greeted warmly by the station's current crew
The three new arrivals were greeted warmly by the station's current inhabitants, commander Pavel Vinogradov, Williams and European Space Agency (Esa) astronaut Thomas Reiter.
Ms Ansari, an American businesswoman, is the first female space tourist and the fourth private space traveller to visit the ISS following Dennis Tito, Mark Shuttleworth and Greg Olsen.
The trio blasted off on 18 September on a Soyuz rocket from the Baikonur Cosmodrome in Kazakhstan.
Ms Ansari's space holiday lasts until the end of the month. She will then come back to Earth with Vinogradov and Williams.