Challenger Cost: $3.2 Billion

The Challenger disaster cost the nation $3.2 billion and rocket seals suspected of triggering the explosion should be redesigned before shuttles fly again even if they are absolved of blame, the head of NASA said today.

Acting Administrator William Graham also said the space agency is taking a fresh look at tentative plans to launch the three remaining shuttles three weeks apart three years after the ships are cleared to fly again, expected some time next year.