Discovery at Edwards Air Force Base in California

The U.S. space shuttle Discovery has landed in California safely, ending the first shuttle mission since the loss of the orbiter Columbia in 2003. The touchdown concluded a mission to re-supply and repair the International Space Station. And the shuttle itself underwent an unexpected repair in orbit. The landing was one day late because of bad weather on the ground.

For the second day, flight controllers diverted Discovery from the preferred Florida landing site because of storms. Instead, they ordered it to glide down to Edwards Air Force Base in the California desert on the other side of the country.

With memories of the Columbia accident still fresh, an obviously relieved mission control welcomed commander Eileen Collins and her crew home after two weeks in orbit.

MISSION CONTROL: "Congratulations on a truly spectacular test flight. Welcome home, friends."

COLLINS: "Thank you. Those are great words to hear. We're happy to be back and we congratulate the whole team for a job well done."

Shuttle program manager Bill Parsons says Discovery's return is a tribute to the fallen Columbia astronauts.

"Today we honored the Columbia crew. We brought Discovery home safely. It's a great day. If you want to know how I feel, I feel fantastic," said Mr. Parsons.

Steve Robinson pulls out a protruding piece of filler fabric from between heat tiles on the underside of the Discovery orbiter

Discovery's mission is the last for an unknown period of time. The U.S. space agency NASA has grounded the shuttle fleet again until it can determine why a piece of hard insulation foam broke off from the orbiter's external fuel tank during liftoff. This was the same kind of mishap that damaged the shuttle Columbia's wing, dooming it to perish upon re-entry, killing all seven people aboard.

NASA chief Michael Griffin says the agency will try to launch another shuttle to the space station in September, but he is not making promises.

"Shuttle flights cannot be conducted according to a schedule," explained Mr. Griffin.  "We are going to use the remaining shuttle flights to complete the building of the space station, but we will fly each shuttle mission when it is ready to go."

Unlike Columbia, Discovery escaped serious damage from the launch debris, but an unprecedented array of shuttle cameras and in-flight inspection techniques installed because of the Columbia accident showed minor damage to some protective tiles and part of a thermal blanket.

NASA determined that these would not threaten the orbiter during re-entry, but it did send an astronaut on an emergency repair spacewalk to remove two thin strips of fabric that had emerged from between the tiles. Engineers feared the protrusions could upset airflow around the shuttle and increase the extreme re-entry heat.

Despite these problems, Bill Parsons calls Discovery's mission a success, not only because it resupplied and maintained the space station, but also because it provided engineers their first results of the safety improvements they made after Columbia's demise.

"We always knew this was a test flight that was going to give us a lot of information," explained Mr. Parsons.  "We have some things that we learned and that we have to go work on, but I think that now it's clear what it is we have to work on and we'll go do that."

Discovery will return to its Florida launch site in about one week attached to the back of a jumbo jet airliner.