Shuttle Discovery bolted to external tank; roll out stays on schedule

The shuttle Discovery, being lowered into position for attachment
to its external tank and boosters. (Photo: NASA)

Engineers successfully re-positioned a wayward nut in the shuttle Discovery's aft engine compartment and finished bolting the orbiter to its external fuel tank early Saturday, keeping the ship on track for roll out to pad 39A Sept. 20 and launch on the ship's 39th and final mission Nov. 1.

Discovery was hauled from its processing hangar to the Vehicle Assembly Building Thursday. A large sling was attached to the orbiter late in the day and the shuttle was rotated vertical and lifted into the high bay where its external tank and boosters were waiting.

Engineers successfully attached a large separation system bolt on the lower right side of the shuttle's belly, but an internal nut on the left side near a 17-inch liquid hydrogen feed line slipped out of position and fell away inside the aft compartment. The explosive bolts are part of a system that ensures the tank separates from the shuttle after the ship reaches orbit.

Troubleshooters initially worried Discovery would have to be removed from the tank and placed back in a horizontal orientation to make repairs. But they later concluded they could safely open the aft compartment, set up access platforms and reposition the nut with Discovery in a vertical and partially mated configuration.

That work was completed early Saturday and the ship was "hard mated" to the tank at 9:27 a.m. EDT.