Rocket Shipment Canceled

WASHINGTON — Morton Thiokol Inc. today canceled the scheduled Saturday shipment to Cape Canaveral, Fla., of booster rockets for the first post-Challenger space shuttle flight, as engineers focused on the rockets’ nozzle movement to learn why a new component broke into pieces.

The rockets, which were to have been used for the flight in June, were built with the same “boot ring” that broke in a full-scale test firing last week. “We were scheduled to start shipping the flight motors to the cape on Jan. 2,” said Thomas Russell, a Morton Thiokol vice president. “At this point, we don’t believe that is going to happen.”