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KENNEDY SPACE CENTER, Florida (CNN) -- NASA has grounded its space shuttles until engineers solve the recurring problem of falling debris, NASA's mission managers said Wednesday.
Pieces of debris tore away from the shuttle Discovery during liftoff Tuesday -- despite NASA spending hundreds of millions of dollars trying to prevent a repeat of the problem that caused the 2003 Columbia disaster.
A piece of insulating foam falling from the external fuel talk during Columbia's launch was blamed for the deaths of its seven crew.
NASA officials say they do not believe falling foam actually hit Discovery.
"Until we fix this, we're not ready to go fly again," shuttle program manager Bill Parsons told reporters at Johnson Space Center in Houston, Texas. "You can say that means they're grounded."
Wayne Hale, deputy shuttle program manager, added: "We are treating it very seriously. Are we losing sleep over it? Not yet."
Discovery is due to return to Kennedy Space Center August 7. A date for the next planned mission has not been set.
Earlier Wednesday NASA lead flight director Paul Hill said that, based on engineers' "first-blush" analysis of falling debris, there was "no significant problem" with the orbiting shuttle.
Hill spoke to reporters after astronauts, using a robotic arm equipped with a camera and laser, spent "one hell of a day" poring over every inch of Discovery for surface damage.
Of the Discovery's seven-member crew, three spent the entire day operating the 50-foot robotic arm and its 50-foot boom extension. Other members who had a spare moment from their tasks "were also there helping to look out the windows and look at camera views," Hill said.
NASA was analyzing data from the launch and from the robotic arm to decide what steps to take next.
"We should start seeing the jury coming in on those decisions by the end of the crew's day tomorrow," Hill said.
Although the search for damage was already included as part of the mission, video from an array of cameras raised concerns after showing a piece of debris falling away from the orbiter's underside during Tuesday's liftoff.
NASA officials said the debris could have broken off from a tile near a door covering the nose landing gear. Space shuttles have shed tile during previous missions without consequences.
The February 2003 Columbia disaster prompted NASA to ground the shuttle fleet and make safety-related activities a priority.
NASA flight operations manager John Shannon said the debris that broke off may be the tile covering rather than the tile itself. He said that initial estimates show it was about 1.5 inches long.
Footage from Discovery's launch also showed a piece of debris falling from the external fuel tank at the time it separated from the orbiter. That debris did not strike the orbiter, he said.
Footage also showed that the external fuel tank's nose cone hit a bird about 2.5 seconds after liftoff -- when Discovery was probably traveling too slowly to sustain any damage, he said.
As the orbiter approaches the international space station for a scheduled Thursday 7:18 a.m. ET docking, the station's crew will photograph Discovery to look further for any damage.
Shuttle crew members plan to test repair techniques during three scheduled space walks by astronauts Steve Robinson and Soichi Noguchi of Japan. The astronaut pair also plans to service the space station.
Since Columbia, NASA has developed contingency plans for astronauts to try to repair damaged shuttles so they can return to Earth. In the event a spacecraft cannot be repaired, plans call for the crew to take refuge in the space station until a rescue mission can be launched.
CNN's Miles O'Brien, Marsha Walton and Kate Tobin contributed to this report.
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