The leak-plagued shuttle Columbia likely will remain grounded until at least early December because of work to repair components in the ship's engine room that are leaking explosive hydrogen, officials say.

"I'm hopeful we will have gone through this entire (test) sequence and have Columbia back in the flying sequence in the December time frame and pull the (mission) off then," William Lenoir, NASA's associate administrator for space flight, said Wednesday at a Washington news conference.The space agency is gearing up to launch the shuttle Discovery Oct. 6.