Hail Damage to Delay Liftoff of Space Shuttle

Space shuttle Discovery’s flight to the new space station will be delayed at least a week so technicians can patch holes carved into the fuel tank by hail, officials said Thursday.

Discovery was supposed to blast off May 20 with 1 1/2 tons of gear for the space station. Instead, it is headed back to the hangar this weekend for repairs, with liftoff targeted for no earlier than May 27.

“We’ll take the amount of time it takes to go fix the vehicle correctly,” shuttle processing director Dave King said after Thursday’s decision. “We think that’s a week to 10 days at this point.”

Hail gouged about 150 holes into the foam insulation on Discovery’s 15-story external fuel tank during a severe thunderstorm over the weekend. At least 35 of the nicks are in an area that can’t be reached from the launch pad.

The largest visible hole on the tank is 2 inches wide and one-third of an inch deep. Most are much smaller.

Engineers are worried that ice could form in the holes when the tank is filled with super-cold fuel in the final hours of the countdown. If chunks of ice broke off at liftoff, the shuttle could be damaged. The cockpit windows are especially vulnerable.

Shuttles have been rolled off the pad and back into the Vehicle Assembly Building only 12 times before.

In 1995, Discovery was sent back because of fuel tank damage caused by a pair of woodpeckers that drilled about 200 holes in the rust-colored foam insulation, apparently in an attempt to roost and build nests.

Discovery’s 10-day ferry mission will be the year’s first shuttle flight. The last was in December, when Endeavour carried up the first U.S.-built section of the station.