Washington  - The US space shuttle Discovery's landing on Friday has been moved to Edwards Air Force Base in California from the Kennedy Space Centre because of rain and thunderstorms near Cape Canaveral in Florida, NASA said.

Discovery was set to land back on Earth at 8:53 pm (0053 GMT), following another postponement due to bad weather. Stormy weather is common during summer evenings in sub-tropical Florida.

The touchdown was originally scheduled for Thursday night, but NASA had to cancel two provisional landing times. The shuttle also had to avoid a piece of space junk on its flight to Earth, the space agency said.

In total, four landing times have been planned between Friday night and Saturday afternoon.

Discovery, which has seven astronauts on board, has enough supplies and energy to last in orbit until Sunday. NASA would prefer to have the shuttle land in Florida. A landing in California would mean high transportation costs back to the Kennedy Space Centre.

Discovery's launch was also delayed three times because of bad weather and technical problems.

The crew of six US and a Swedish astronaut delivered to the International Space Station (ISS) a new sleeping compartment and a treadmill named for television comedian Stephen Colbert, as well as two racks for scientific experiments and a freezer to store experiments set to be sent back to Earth.

One of the racks will be used to conduct research on metals, semiconductors, crystal, glass and other materials in microgravity. The other will be used to study liquids and gels in space.

During three spacewalks, astronauts replaced an empty ammonia tank and made other repairs. (dpa)