NASA this evening delayed the launch of its first space shuttle mission since the 2003 Columbia disaster after engineers discovered a problem with one of shuttle Discovery's fuel sensors, NASA's launch commentator said.
"We will not be able to fly today," said commentator George Diller.
The space shuttle Discovery on the launch pad at Kennedy Space Center
Earlier today a last-minute mishap caused by a falling window cover, briefly cast doubt on the launch schedule after it damaged two heat resistant tiles near the rear of the shuttle.
Nasa engineers replaced the panel, which was said to be a routine procedure.
Today was to have been he first space shuttle mission since the Columbia shuttle disintegrated 2 1/2 years ago, killing seven astronauts and spilling debris over Texas.
Columbia fell apart on February 1st, 2003, because falling foam from the external fuel tank had knocked a hole in its wing during liftoff 16 days before. When the shuttle returned to the Earth's atmosphere, superheated gases ate into the breach.
Much of NASA's efforts since have been directed at minimizing the possibility of falling debris at liftoff and one of Discovery's main missions will be to see whether those efforts have paid off, and to try out experimental repair techniques if they have not.
Weather conditions will have to be perfect, not just in the flight path but at emergency landing zones at Cape Canaveral, elsewhere in the United States and in Europe.