Discovery completes mission STS-133, landing at Kennedy Space Center in Florida on March 9, 2011. Photo by NASA TV

NASA's most flown orbiter and its six veteran astronauts landed 8:57 a.m. PST at Kennedy Space Center. They completed a 13-day mission that delivered supplies, a new storage module and the first human-like robot to the International Space Station.

Discovery spent 365 days in space and traveled nearly 150 million miles during its 27-year career.

"It was a great day to come back and land in Florida, we're happy to bring Discovery home," said Commander Steve Lindsey, but added, “[i]t kind of got sadder for me as the minutes rolled past.” 

Lindsey was joined on the STS-133 mission by pilot Eric Boe and mission specialists Alvin Drew, Steve Bowen, Mike Barratt and Nicole Stott. Bowen replaced Tim Kopra, who suffered a bike injury in January. 

Kopra maintained contact with the crew during the mission. "He actually helped us through the EVA's (extravehicular activities, or spacewalks) from the ground, which I greatly appreciated," said Bowen, who with Drew, each completed two spacewalks to install space station parts and conduct other maintenance.

The originally 11-day mission was extended primarily to unpack and outfit the new module Leonardo-- which provides 2,472 cubic feet of pressurized volume for storage and scientific use-- and fill the H-II Transfer Vehicle with trash before its planned undocking in late March.

Well over 100 percent of the on-orbit mission objectives was accomplished and landing was outstanding thanks to the Discovery team above and on the ground, said Mike Leinbach, shuttle launch director. “It was virtually a perfect mission.”

"This is very bittersweet for all of us," said NASA Administrator Charlie Bolden, who was present to greet the astronauts. "Discovery holds a special place for me and for (Kennedy Space Center Director) Bob Cabana over here because we both had the opportunity to fly on it twice."

Discovery's farewell marks the beginning of the end to the 30-year shuttle program. Only two missions remain: Endeavour's STS-134 in April and Atlantis' STS-135 in June, both to the space station.

NASA will continue to use Russian Soyuz spacecraft to ferry crew to and from the space station after the shuttles retire later this year. However, the NASA Authorization Act of 2010 signed into law last October pushes NASA to increase American commercial partnerships to fill those transportation needs while the agency develops its own heavy-lift rocket and crew capsule that could take humans beyond low-Earth orbit by 2016.

(Obama's FY 2012 budget request provides for both the development of the commercial crew industry to support space station/low-Earth orbit missions, and the heavy-lift rocket and crew capsule to support beyond low-Earth orbit/eventual deep space/backup space station missions. But many congressional members criticized the budget because, according to them, it does not prioritize the heavy-lift rocket and crew capsule enough.)

Bill Gerstenmaier, associate administrator for Space Operations, said last week's Glory satellite launch failure due to a Taurus XL rocket malfunction, is a reminder that spaceflight is not easy.

Gerstenmaier said STS-135-- which is moving forward although funding is pending as Congress continues to work out a budget for the remainder of FY 2011--would provide commercial companies more time to develop. “With this flight, that delays the criticality of those commercial partners coming online until probably the end of 2012.” 

Once retired, shuttles will be shipped to a different site each for permanent display. But locations won't be announced until April, officials said.

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