Experts Examine 2-Ton Chunk of Shuttle Segment That Failed

Experts seeking to determine precisely what caused the explosion of the space shuttle Challenger examined a two-ton piece of rocket wreckage Tuesday that contains part of the joint that failed and apparently triggered the accident.

As the scorched 11-by-20-foot chunk was unloaded from the salvage ship Stena Workhorse, observers could see a large hole that had been burned through the joint between rocket segments and the surrounding steel casing. The Navy said the hole measured 15 by 28 inches.

Launching day photos show a plume of flame spewing from this joint, and investigators believe it burned through the bottom rocket attachment, allowing the top of the solid-fuel booster rocket to swivel and crash into the shuttle’s huge external fuel tank.

Hoisted From Ocean Floor

The crew of seven died in the explosion that occurred 73 seconds after the shuttle lifted off on Jan. 28.

The Stena Workhorse recovered the piece Sunday, hoisting it from 560 feet down on the floor of the Atlantic Ocean.

The presidential shuttle commission said Monday that the recovery was of “critical interest” to its investigation. Commission member Eugene E. Covert and members of the commission staff were among those who examined the piece Tuesday.

Meanwhile, divers combing the wreckage of Challenger’s crew cabin may have found more astronaut remains Tuesday, according to radio traffic monitored by news organizations.

Coded Message

A coded message from the salvage vessel Pierce referred to a “Tom O’Malley,” a term used earlier by ships in the cabin search area. It is believed to indicate the discovery of remains.

After stormy weather left a blanket of silt over what remains of the cabin last week, sources close to the investigation said divers were certain they would recover no more remains.

However, the sources, who spoke on the condition that they not be identified, said some remains of one of the crew members had not been found. They said that, when the weather cleared, a scallop boat was hired for a day to help clear the silt, and the search was resumed.