Technicians using ultrasonic devices were trying to determine Friday if an insulation problem on a booster rocket is serious enough to delay the next shuttleflight.

NASA said the separation of the insulation was found Thursday on the bottom edge of one of four segments that make up the right rocket. Officials said if the debonding has not spread beyond that, it can be repaired here without affecting the Aug. 4 launch schedule.Sources who requested anonymity said if the separation extends deeper into the insulation, the segment might have to be returned to the Morton Thiokol plant in Utah for another segment, which could delay the launch several weeks.