The Space Shuttle Discovery (search) touched down safely in California Tuesday after spending two weeks in space, making it the first successful shuttle landing since Columbia (search) broke apart upon re-entry over two-and-a-half years ago.

"This experience we had was just an absolutely wonderful, breathtaking challenge -- it was a huge achievement," shuttle Commander Eileen Collins said during a news conference with the other crew members hours after the landing. "We saw some of the most beautiful parts of Earth."

She added: "This crew accepted the challenge doing this flight knowing the risks involved because we know how important space flight is."

The shuttle landed at 8:11 a.m. EDT, one minute early.

"Congratulations on a truly spectacular test flight," Mission Control said once Discovery came to a stop. "Welcome home, friends."

"We're happy to be back and we congratulate the whole team for a job well done," replied Collins, who manned a picture-perfect landing.

Buzz Aldrin, the second man to walk on the moon, told FOX News that the space program has come a long way since 1969, when he walked on the moon.

"The progress is just phenomenal — what we've been able to do since then and I think the shuttle will go down in history as such a marvelous vehicle. Maybe it's not what everyone wanted to see, but it has performed so well and we've learned so much out of all of these missions," Aldrin said.

After thunderstorms in Florida prevented the spacecraft from returning to its home base, NASA officials rerouted the shuttle to Edwards Air Force Base in the Mojave Desert.

"Today we honored the Columbia crew. We brought Discovery home safely," shuttle program manager Bill Parsons said during a news conference after the landing. "It's a great day."

Launch director Mike Leinbach said the shuttle program had "come full circle now."

White House spokesman Trent Duffy called it "a proud day for America."

The instability of the weather at Cape Canaveral, Fla., and storms popping up near the landing strip there prompted NASA (search) to turn to its backup site. On Monday, low clouds prevented a return to the cape.

Collins and her co-pilot, James Kelly, slowed Discovery's speed enough to drop the shuttle out of orbit about an hour before touchdown.

The inherently dangerous ride down through the atmosphere — more anxiety-ridden than normal because of what happened to Columbia 21/2 years ago — skipped most of the continental United States this time.

Discovery followed a course that took it over the Pacific and into Southern California. NASA officials had said they would adjust the flight path so the shuttle would skirt Los Angeles, because of new public safety considerations by NASA in the wake of the Columbia accident.

The detour to the opposite coast was a big disappointment for the astronauts' families, who had been waiting to greet their loved ones in Cape Canaveral. Their reunion was put on hold until Wednesday, when they all planned to meet in Houston.

NASA's top officials also had gathered at Cape Canaveral to welcome the crew home.

"It's going to be a new beginning for the space shuttle program," NASA's spaceflight chief, Bill Readdy, said from the Cape Canaveral landing strip.

NASA: 'We're Coming Back'

With its launch on July 26, Discovery became the first shuttle to fly since Columbia's catastrophic re-entry in 2003. But its flight to the international space station could be the last for a long while.

NASA grounded the shuttle fleet after a nearly 1-pound chunk of insulating foam broke off Discovery's external fuel tank during liftoff — the very thing that doomed Columbia and was supposed to have been corrected.

NASA called it a test flight and it was — in an alarming way no one anticipated. A potentially deadly 1-pound chunk of foam insulation came off the redesigned fuel tank during liftoff, missing Discovery but demonstrating that the space agency had not resolved the very problem that doomed Columbia.

The foam loss prompted NASA to ground future shuttle flights.

Shuttle managers freely acknowledged the mistake, while stressing that the inspection, photography and other shuttle data-gathering systems put in place for this flight worked exceedingly well. What's more, no severe damage was detected on Discovery while it was in orbit.

"I hope this shows people that we're coming back," Readdy said following touchdown. "We've got some more work to do. We know what we need to do and we'll do it."

Collins told reporters Tuesday afternoon that the shuttle orbiter performed "magnificently."

"We felt very safe" during the entire operation, she added.

A torn thermal blanket under a cockpit window was left as is, after engineers decided it posed little risk as re-entry shrapnel.

Two pieces of filler material dangling from Discovery's belly, however, were removed by a spacewalking astronaut last week, for fear they could lead to a repeat of the Columbia tragedy. The fabric strips slipped out of the narrow gaps between thermal tiles for reasons unknown.

NASA officials said a space shuttle will not fly again until the foam problem is solved and engineers understand why the two so-called gap fillers came loose.

Until the spacewalk to pull out the two protruding gap fillers, astronauts had never ventured beneath an orbiting shuttle or made repairs to its fragile thermal shielding.

"It's going to be a new beginning for the space shuttle program," Readdy said. "The approach that we've taken has to do with a very methodical series of flight tests. It's exactly the right approach.

"This was certainly the most documented flight in shuttle history," he added.

The shuttle astronauts spent nine days at the international space station, restoring full steering capability to the orbiting outpost, delivering much-needed supplies and replacement parts, and hauling away a 21/2-year backlog of trash.

They successfully conducted three spacewalks, including one to test new tools and methods for fixing a damaged shuttle heat shield in orbit. They also pulled off some fancy new flying maneuvers, flipping Discovery end over end near the space station so its two residents could zoom in with cameras as part of the exhaustive search for shuttle damage.

Flight director LeRoy Cain said over the weekend that not only did NASA learn a lot about the shuttle with this mission, but "we've learned a lot about ourselves."

Following the Feb. 1, 2003, Columbia catastrophe, NASA revamped the way it managed a shuttle mission. The mission management team met daily while Discovery was in orbit, taking time to listen to dissenting opinions and encouraging them as well, according to its chairman, deputy shuttle program manager Wayne Hale. Every potential serious problem was analyzed by a team of engineers and, in the case of the ripped blanket, even prompted a series of wind tunnel tests.

Some accused the space agency of going too far to reach a group consensus and having "analysis paralysis." Shuttle officials denied that was so and said their intent was to put the astronauts' safety first no matter what, an assessment shared by Discovery's co-pilot, Kelly.

"Just the fact that we're here means we don't have paralysis by analysis," Kelly said from orbit Sunday. "The folks on the ground have done an absolutely great job trying to take care of everything they possibly can."

The Associated Press contributed to this report.