New Engine for Challenger to Be Tested

Engineers have taken a big step toward the resumption of space-shuttle flights by developing a rocket engine that should prevent failures like the one that destroyed Challenger, the leader of a Marshall Space Flight Center team announced today.

“We’ve taken every step to understand what happened on Challenger and to preclude that from happening again,” said John Thomas, the manager of the solid rocket motor redesign team. “We are well on the way to accomplishing a good, safe redesign.”

Thomas said the engineering team has settled on a fundamental new design that will prevent the problem that led to the Jan. 28 Challenger accident that killed seven crew members.

He said that partial full-scale testing of the new design will begin late this fall and that test-firing of qualification motors will be held in the fall of 1987.

If the redesigned motor passes all the tests, Thomas said, space-shuttle flights could resume in the first quarter of 1988.

Shuttle Fleet Grounded

A presidential commission blamed the Challenger disaster on failure of a solid rocket booster joint. The National Aeronautics and Space Administration grounded the shuttle fleet until the design flaw could be corrected.

The commission said Challenger exploded because two O-rings became unsealed and permitted superheated gases to burn through the wall of a propellant tank. Fuel and oxidizer from the tank erupted in a fireball.

Thomas, at a news conference at the space flight center here, said the new design will include a third O-ring and a metal lip that will force the engine joint to remain sealed. He said it also has interlocking insulation to prevent hot gases from touching the rubberized O-ring seals.

He also said bolt assembly will be added to provide additional rigidity between the rocket nozzle and the rocket casing.

Rigid Under Pressure

By installing a metal lip, Thomas said, the joint will be held rigid under pressure.

“No matter what happens with movement of the joint, one of those (three O-rings) will close,” he said.

On Challenger, the rocket engine seals were designed to be activated when pressure surged against them at rocket ignition. Under the new design, said Thomas, a pressure surge is not needed to achieve a seal.

Thomas said heaters installed in the new rocket joint will maintain the temperature even in frigid conditions.

He said design teams are continuing to study four other rocket engine concepts that could be used should tests prove that the primary design does not work.