Thunderstorms forced NASA to call off Saturday's launch of Discovery, delaying the first space shuttle flight in a year by a day.
More bad weather was forecast for Sunday and for the rest of the weekend.
Storm clouds moved in and out of the launch zone throughout the morning and early afternoon, posing lightning threats. As the countdown held at the nine-minute mark, it became clear the weather would not improve, and launch director Mike Leinbach announced a one-day delay.
"We're not going to make it today," Leinbach said. "It's not a good day to launch the shuttle. So we're going to try again tomorrow."