The Discovery space shuttle and its six-strong crew have returned to Earth after a 13-day mission to the International Space Station.
The orbiter touched down at the Kennedy Space Center in Florida at 1314 GMT.
Mission control had raised concerns about weather conditions, but gave the go-ahead shortly before the ship began its hour-long descent.
Nasa hopes the mission's apparent success has drawn a line under doubts over the shuttle programme's safety.
"Welcome back Discovery and congratulations on a great mission," mission control told shuttle commander Steven Lindsey, as the orbiter came to a halt on the runway after deploying its parachute.
"It was a great mission. A really great mission," Lindsey replied.
Discovery was cleared for re-entry over the weekend when inspections revealed no signs of damage to the craft.
The orbiter's flight was only the second shuttle mission since the Columbia broke up on re-entry in 2003 killing everyone on board and grounding the rest of the shuttle fleet.
Six-month stay
Crew members were woken early on Monday to begin preparations for re-entry, one of the riskiest phases of a shuttle mission.
DISCOVERY SHUTTLE FLIGHT
Mission known as STS-121
Discovery's 32nd flight
18th orbiter flight to ISS
Landing: 0914 EDT (1314 GMT)
Landing location: Kennedy Space Center, Florida
Returning crew: Lindsey, Kelly, Fossum, Nowak, Wilson, Sellers
Mission control waited until almost the last minute to confirm the weather was good enough for the shuttle to return.
There had been some worry over a bank of rain clouds in northern Florida which were expected to head towards the landing site.
Once the go-ahead was given, Steven Lindsey and co-pilot Mark Kelly started the spacecraft's plunge out of orbit.
The shuttle reached a velocity of nearly 25 times the speed of sound as it hurtled through the atmosphere, generating huge amounts of heat.
No problems were reported with the ship's heat shield, and the shuttle touched down on schedule under overcast skies.
The orbiter has returned a man lighter than at take-off, having left German astronaut Thomas Reiter on board the International Space Station for six months.
'Back on track'
Ahead of the landing, Mr Lindsey said Discovery's incident-free mission should dispel lingering doubts over the safety of the shuttle programme.
"I hope our legacy was that we closed out the return-to-flight test portion of the programme following the Columbia accident," he told ABC TV in the US.
"I personally believe we are back on track."
Accident investigators said the Columbia disaster had been caused by insulating foam falling from the vehicle's external fuel tank during launch, striking the orbiter's wing and damaging the heat shield needed to protect it during re-entry.
Discovery's heat shield was examined in detail just after launch and just before re-entry. Astronauts used a laser and camera system to check over the ship's nose and belly.
The final inspection was geared in particular to look for micrometeoroid impacts that could have damaged the shuttle during its stint in space.
The Discovery mission undertook three spacewalks, including doing repairs on the ISS that were vital to resuming building work on the platform.
Source:-- 1'st BBC
2'nd NPR
The orbiter touched down at the Kennedy Space Center in Florida at 1314 GMT.
Mission control had raised concerns about weather conditions, but gave the go-ahead shortly before the ship began its hour-long descent.
Nasa hopes the mission's apparent success has drawn a line under doubts over the shuttle programme's safety.
"Welcome back Discovery and congratulations on a great mission," mission control told shuttle commander Steven Lindsey, as the orbiter came to a halt on the runway after deploying its parachute.
"It was a great mission. A really great mission," Lindsey replied.
Discovery was cleared for re-entry over the weekend when inspections revealed no signs of damage to the craft.
The orbiter's flight was only the second shuttle mission since the Columbia broke up on re-entry in 2003 killing everyone on board and grounding the rest of the shuttle fleet.
Six-month stay
Crew members were woken early on Monday to begin preparations for re-entry, one of the riskiest phases of a shuttle mission.
DISCOVERY SHUTTLE FLIGHT
Mission known as STS-121
Discovery's 32nd flight
18th orbiter flight to ISS
Landing: 0914 EDT (1314 GMT)
Landing location: Kennedy Space Center, Florida
Returning crew: Lindsey, Kelly, Fossum, Nowak, Wilson, Sellers
Mission control waited until almost the last minute to confirm the weather was good enough for the shuttle to return.
There had been some worry over a bank of rain clouds in northern Florida which were expected to head towards the landing site.
Once the go-ahead was given, Steven Lindsey and co-pilot Mark Kelly started the spacecraft's plunge out of orbit.
The shuttle reached a velocity of nearly 25 times the speed of sound as it hurtled through the atmosphere, generating huge amounts of heat.
No problems were reported with the ship's heat shield, and the shuttle touched down on schedule under overcast skies.
The orbiter has returned a man lighter than at take-off, having left German astronaut Thomas Reiter on board the International Space Station for six months.
'Back on track'
Ahead of the landing, Mr Lindsey said Discovery's incident-free mission should dispel lingering doubts over the safety of the shuttle programme.
"I hope our legacy was that we closed out the return-to-flight test portion of the programme following the Columbia accident," he told ABC TV in the US.
"I personally believe we are back on track."
Accident investigators said the Columbia disaster had been caused by insulating foam falling from the vehicle's external fuel tank during launch, striking the orbiter's wing and damaging the heat shield needed to protect it during re-entry.
Discovery's heat shield was examined in detail just after launch and just before re-entry. Astronauts used a laser and camera system to check over the ship's nose and belly.
The final inspection was geared in particular to look for micrometeoroid impacts that could have damaged the shuttle during its stint in space.
The Discovery mission undertook three spacewalks, including doing repairs on the ISS that were vital to resuming building work on the platform.
Source:-- 1'st BBC
2'nd NPR