HOUSTON, Texas — Discovery made a safe return to Earth Tuesday 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 Center 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.
And it signaled a growing awareness among NASA's ground team and astronauts that the vaunted shuttle program is winding down, marking the end of an era in human spaceflight.
"It's a little bit bittersweet, but we do have to recognize that like anything else, there does have to be an end to any major program," said Pete Nickolenko, NASA's launch director, during a post-landing news briefing.
"We recognize that we are facing that, that we are coming up to it," he said.
Meanwhile, Bryan Lunney, the NASA flight director who supervised Discovery's descent and will also oversee the final shuttle flight, said it is a bit too early to get misty-eyed.
"For me, we are heads down focused on the mission, trying to make sure it's safe and successful," he said.
"I haven't gotten too philosophical or concerned about the future. I'm just taking care of business," Lunney said.
Discovery dropped from orbit Tuesday 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.
The shuttle'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 observation rack to hold cameras and spectral scanners for studies of the atmosphere, geological formations, and 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 bulky 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.
During its 12-day mission, six astronauts will deliver a Russian mini-research module and external spare parts, including power storage batteries, a communications antenna and a radiator as well as Canadian and European robot arm components.
Endeavour is to follow, with a launch scheduled for July 29. Its cargo includes the Alpha Magnetic Spectrometer, an internationally-sponsored physics investigation for the study of cosmic radiation and anti-matter.
If the scheduling holds, Discovery will lift off for the station on September 16 for the final shuttle flight carrying yet more cargo and a pressurized storage module.