Nasa puzzled over mysterious debris:

Endeavour astronauts inspected the space shuttle’s heat shield Wednesday, while Nasa puzzled over a mysterious piece of debris that may have struck the shuttle’s nose just after launch.Officials at the Johnson Space Center in Houston, Texas refused to speculate on the origin or even the size of the debris captured on camera 10 seconds after launch. Nor are they sure if it struck the shuttle. "It looks like it’s not coming from the orbiter, and you can’t really tell if it strikes the orbiter or not," flight director Mike Moses said. "I can’t even begin to speculate on what it could be," Moses said.