Delicate work ahead on tank

A crew of about 100 people at Kennedy Space Center are scrambling to get in place everything they need for the unprecedented repair work on a hail-battered space shuttle external tank.

Reporters got a close-up look today at the complicated network of custom-built scaffolding and other repair tools necessary to fix the holes and gouges made in the tank by a freak hail storm at the launch pad.

There is no real change in the repair planning as it pertains to when the shuttle will launch. As of now, NASA is hurrying ahead in hopes that repairs to the tank might allow a launch in the final days of a launch window that ends May 23. But officials repeated today that they might not make it.

A decision-point ahead is April 10. Another external tank is about to be shipped to KSC from Michoud Assembly Facility in New Orleans. It would arrive around April 10, or maybe a few days before then. NASA plans to decide then whether to repair and fly this tank or trade tanks.

That decision will be made based on whether the agency has determined the repaired tank will be safe to fly and which option gets the shuttle back out to the launch pad the fastest.

If NASA can't fly in May, the next available window opens June 8. Right now, teams are working on the rippling impact on the overall construction schedule for the International Space Station. The goal is to regain time lost to this hail incident over the course of this year and 2008.

The work to repair the bottom two-thirds of the tank and some minor damage on the orbiter's heat-shielding tiles is complete. The harder effort ahead involves the top portion of the tank. An arm's length look today at the top of the fuel tank, inside the Vehicle Assembly Building, demonstrated the task ahead is a complicated one.

The tank's foam appears to have been riddled with hail hits in a very concentrated area.

At the very top of the tank, workers have sanded off about a half-inch of the three or so inches of foam insulation in that area. They've been smoothing the area for a never-before-tried-at-KSC foam spray. That work, typically done by robots at the factory to ensure perfection, will be done by humans toting spray guns on platforms suspended from above.

Just below that, hundreds of white spots on the tank will be filled with a liquid form of the foam using a syringe. Molds and sanding tools will be used to smooth the surface once the repair foam expands and hardens in place. The repair areas are being marked and prepared now and some initial setup work has been done for the first repairs. The dings are the size of nickels and quarters, but in the worst places there are dozens of them within an inch or so of one another.

All around the area, high inside the VAB, space center workers had to engineer and then assemble custom scaffolding that is close enough to the tank's delicate foam insulation to let workers reach out and touch it but strong enough to not bend and collide with the foam. The insulation is so delicate that the press of a human finger could do enough damage to pose a safety threat to the shuttle in flight.

Whether the damage tank flies on this mission or not, the repair work will be done. The tank will eventually be repaired and flown - as soon as the very next shuttle mission later this summer.