CAPE CANAVERAL, Fla. (AP) _ Space shuttle Discovery's flight to the new space station will be delayed by at least a week so technician's can patch holes carved into the shuttle fuel tank by hail.

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

Shuttle managers made the decision Thursday following an extensive engineering analysis.

Hail gouged about 150 holes into the foam insulation on Discovery's 15-story external fuel tank during a severe thunderstorm over the weekend. About 13 of the nicks are in an area that cannot 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.

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 space station.

It's the longest gap in shuttle launches since flights resumed in 1988 following the 1986 Challenger disaster.