The US space shuttle Discovery returned safely to Earth today after completing a 15-day resupply mission to the International Space Station.
Discovery, with its crew of seven astronauts, glided to a smooth landing at the Kennedy Space Centre in Florida at 1.08pm Irish time, ending the 131st trip of the shuttle programme.
The shuttle and crew returned from a 10-day stay at the space station, a $100 billion project of 16 countries that has been under construction since 1998.
Discovery's commander Alan Poindexter and pilot Jim Dutton fired the shuttle's braking rockets while over the Indian Ocean to leave orbit and head for the spacecraft's home base in Florida.
Bad weather had delayed a scheduled return yesterday, further extending a mission that had already been lengthened by a day so the astronauts could use the orbiting space station's communications system to relay heat shield inspection results.
Nasa discovered the shuttle's Ku-band communications antenna was broken shortly after Discovery was launched on April 5th, obliging the crew to use the station's system. The inspection procedure was implemented after the Columbia disaster in 2003, which was blamed on a heat shield breach.
Discovery had delivered to the space station a cargo pod, about the size of a small bus, filled with equipment and experiment racks, a fourth US sleeping berth, a darkroom for the station's US laboratory module and other supplies. The returning Italian-built cargo pod was packed with old equipment and items no longer needed on the station.
The shuttle also hauled home a spent tank of ammonia coolant, which will be refurbished and returned to the station as a spare.
A new ammonia tank was installed during three spacewalks by Discovery astronauts Rick Mastracchio and Clay Anderson, but a problem with a valve prevented Nasa from activating the coolant system as planned.
The International Space Station has two coolant loops, and both will need to be operational within about a month to keep the station at full power as the changing sun angle generates more heat on the station.
Discovery's return leaves just three shuttle flights on Nasa's schedule before the ships are retired at the end of the year.
Its sister ship, Atlantis, is due to be rolled out to the launch pad this evening to be prepared for lift-off on May 14th.