CAPE CANAVAREL, FL (Aug. 18)NASA Administrator Michael Griffin announced during a press conference Thursday that the space-shuttle program would address criticisms about delays and setbacks by placing the shuttles on unannounced and impromptu missions. "Those who believe we lack initiative will be happy to learn that, from now on, we go at the drop of a hat," Griffin said. "Whatever experiments are on board when the engines start, those are the ones we do. Astronauts will be permanently quartered in the ready room, and will be notified when they hear the countdown start at, say, 20. It's part of NASA's exciting new..." The rest of Griffin's announcement was inaudible in the overwhelming sound of the Shuttle Discovery, whose crew decided to launch during his speech.