Discovery made a safe return to Earth yesterday after a two-week resupply mission to the International Space Station that broke new ground by putting four women in orbit for the first time.

The shuttle and its seven-member crew finally touched down at Nasa's Kennedy Space Centre in Florida at 9:08 am (1308 GMT) after a series of earlier delays due to rain and fog.

"Welcome home. Congratulations on an outstanding mission," Mission Control said after the Discovery put more women in orbit than ever before, with three female crew joining one woman already on the space station.

"What a great mission," replied Discovery commander Alan Poindexter. "We enjoyed it."

The mission also marked the first time that two Japanese astronauts were in space at the same time with Discovery mission specialist Naoko Yamazaki joining Soichi Noguchi of the Japan Aerospace Exploration Agency.

The shuttle dropped from orbit over the Pacific Ocean and followed a rare course that took it over much of the US upper Midwest and Southeast, leaving a glowing contrail for ground observers.

Discovery's crew delivered nearly eight tonnes of scientific equipment and other supplies intended to fortify the orbiting science laboratory for operations well beyond the final shuttle flight.

The new research gear includes an Earth observations rack to hold cameras and spectral scanners for studies of the atmosphere, geological formations as well as weather induced crop damage.

Another new experiment monitors changes in the muscle and joint health of the astronauts in the absence of gravity. A new freezer will store specimens for medical and biological experiments.

During three spacewalks, two of the astronauts wrestled with balky bolts to replace a boxy coolant tank that is essential to the long term function of the station's life support systems.

Discovery has only one more flight before it is mothballed, while Nasa counts just three more missions until it retires its entire shuttle fleet and embarks on a new phase in human spaceflight.

The US space agency will have to turn to Russia to transport Americans to the orbiting science laboratory while it tries to foster a commercial space taxi industry.

President Barack Obama has drawn fire for shelving plans outlined by his predecessor George W. Bush - which he argues are too costly - for Nasa to develop a new generation of spacecraft for missions to the Moon and Mars.

Shuttle Atlantis will fly next, with a lift off tentatively scheduled for May 14.