The Challenger exploded 73 seconds after liftoff on Jan. 28, 1986, killing all seven members of the crew. A leak in a joint on the right solid-fuel rocket booster was blamed.

Officials said they did not expect today's discovery to shed any new light on the accident.

''We understand what happened with Challenger,'' said Bruce Buckingham, a NASA spokesman. ''There's nothing more we can learn.''

It has been several years since anything from the Challenger has been found. Fishermen usually discover the scraps; in 1991 they found a small tank and a metal fragment a few feet long off Cape Canaveral.

''It brings things back,'' said Bruce Jarvis, father of the astronaut Gregory Jarvis, who died in the accident. ''It's like having a bad wound and you've got a scab. It's like somebody picking at the scab.''

The police said they were tipped off by a motel as well as a radio station that got a call from a listener reporting the debris.