Discovery blasts off

The shuttle roared through a partly cloudy sky at 11:38 am EDT 1538 GMT, defying predictions by meteorologists that clouds and rain could force a delay.

A buildup of ice on the external fuel tank, which could have fallen off and hit the shuttle, was ruled out as a threat by NASA engineers. Cameras showed a lot of debris coming off once the shuttle reached space, where there is little chance of it resulting in serious damage.