Rocket engineers fired a small-scale shuttle booster Monday in an apparently successful test of redesigned O-ring nozzle joints, setting the stage for a crucial full-scale booster firing next week, officials said.
Allan J. McDonald, in charge of the redesign project for Morton Thiokol Inc., which makes the boosters, said he was "very happy" with the test.
He said the booster would be disassembled over the next few days for a complete assessment, but a quick inspection did not show any signs of problems, even though a defect was deliberately built into the joint.
The firing followed a similar test two weeks ago, which indicated that a new version of the type of joint that doomed Challenger 19 months ago will work as intended when the shuttle Discovery blasts off next June on America's next manned space flight.
Unlike the earlier firing, which tested redesigned versions of joints between segments of the booster, called field joints, the test Monday focused on the joint that attaches the giant nozzle to the base of the full-scale rocket.
The "case-to-nozzle" joint has a history of major problems from prior shuttle flights, and most NASA engineers express more concern over this element.