Discovery glided down through an overcast sky onto the Kennedy Space Center runway at 9:14 a.m., allowing NASA to declare total victory for the first time since before the 2003 Columbia disaster.
It was so cloudy, shuttle commander Steven Lindsey couldn't spot the runway until about a minute before landing.
"Welcome back Discovery and congratulations on a great mission," Mission Control told Lindsey after Discovery rolled to a stop.
Later, Lindsey noted that he and his crew accomplished both major objectives: completing the post-Columbia testing of the shuttle and its redesigned fuel tank, and readying NASA to resume building the international space station.
"We're ready to go assemble station," Lindsey said after climbing out of Discovery, "and we're ready to start flying shuttles on a more regular basis."
The smooth landing left NASA officials jubilant, after conquering the chronic threat of foam chunks that break off the external fuel tank during launch still a problem, but not a serious one in this mission.
"This is as good a mission as we've ever flown," NASA Administrator Michael Griffin said. "But we're not going to get overconfident."
The shuttle came in from the south, swooping over the Pacific, Yucatan Peninsula, Gulf of Mexico and across Florida to cap a 5.3 million-mile journey that began on the Fourth of July.
A last-minute buildup of clouds prompted NASA to switch the shuttle's direction for landing. By the time Discovery approached, it was so cloudy, Lindsey couldn't spot the runway until about a minute before landing.
A couple of minutes out, NASA made a racket to keep birds out of the way of the approaching spacecraft. Car horns blared, and the sound of gunshots and firecrackers erupted.
At touchdown, shouts and whistles came from the few hundred astronauts' relatives and space center workers at the runway. "It's exciting to see the shuttle back," said astronaut Scott Kelly, the identical twin brother of Discovery's co-pilot, Mark Kelly. "We're back on track with maybe flying the shuttle regularly here starting again in August."
Atlantis is up next with a crew poised to carry out assembly of the international space station, a task put on the back burner after Columbia.
Congratulations poured in from afar. "A proud nation congratulates the brave shuttle Discovery crew on the completion of their successful return to flight mission," said Sen. Kay Bailey Hutchison, R-Texas.
The buildup of clouds shortly afterward prompted NASA to switch the shuttle's landing direction, CBS News correspondent Bob Orr reports. Officials at Marine Corps Air Station Cherry Point in eastern North Carolina also said they had been alerted for emergency landing duty as a precaution.
The shuttle, with commander Steven Lindsey and co-pilot Mark Kelly at the controls, plunged out of orbit an hour before touchdown Monday morning with the firing of the braking rockets, and began the hour-long descent. The flight path had the spacecraft coming in from the south, swooping over the Pacific, Yucatan Peninsula, Gulf of Mexico and across Florida to cap a 5.3 million-mile journey that began on the Fourth of July.
"It was beautiful," Lindsey told controllers. "We could see the bright orange glow above and I could see the Earth moving below and it was just spectacular. We actually also saw the moon through the plasma (scorching gases), so it was a great entry and a great landing."
NASA was certain that Discovery's heat shield was intact and capable of protecting the spaceship during the fiery re-entry. The shuttle itself was cleared Sunday for landing. CBS News correspondent Teri Okita reports the shuttle crew spent Sunday doing final top-to-bottom checks of the spacecraft. They also tested a leaking unit that powers hydraulics used for steering and braking.