A brief hailstorm at the Kennedy Space Center significantly damaged the external fuel tank of the space shuttle Atlantis on Monday, and NASA officials said yesterday that a mid-March launch of the spaceship will have to be postponed as a result.

The golf-ball-size pieces of ice, which fell only in a small area around the Cape Canaveral launchpad, left hundreds of "dings and divots" that officials said will require repair. Shuttle program manager N. Wayne Hale Jr. said he hoped the work could be finished in time for a launch in April or May, although it could take longer.

The shuttle will be rolled back to the center's assembly building for a detailed inspection that will determine how long the repairs will take. Hale said that for now, NASA's ambitious plan to launch five shuttle missions to the space station this year remains unchanged.

The delay came on the same day that a congressionally mandated review of the international space station program warned that NASA will face a major problem in resupplying the station after 2010. That is when the space shuttles are scheduled to be retired and assembly of the space station completed.

The situation could become so severe that the station crew might have to be reduced in size or the orbiting laboratory might even have to be abandoned, an independent panel of experts wrote.

To avoid that fate, they said the administration, Congress and NASA need to begin a much more aggressive program to replace the space shuttles. The shuttle, along with Russian spaceships, now ferry supplies to the space station. The expanded effort, they said, will cost an additional $1 billion a year starting in 2010.

NASA hopes to have a new space ship, called Orion, ready to fly by 2014, but it remains in the early planning stages. The European and Japanese space agencies are developing unmanned cargo ships that could help fill the gap, and NASA has funded two small American companies that are building rockets and capsules designed to carry cargo. But none of these alternatives has been proved so far.

With NASA's budget already severely squeezed by the competing demands of President Bush's plan to return astronauts to the moon and go on to Mars, in addition to ambitious and popular space and earth science programs, the prospect of substantially greater future costs to support the space station has to be unwelcome.

NASA said top agency officials had received the panel's report only yesterday and had not had time to read it and comment. The lengthy document looked at a wide range of issues related to safety on the space station and concluded that it "is currently a robust and sound program with respect to safety and crew health."

The two most pressing areas of concern, the panel found, were the possibility of small meteors or space debris punching through the station's walls or crew members becoming ill.

Though NASA officials remain optimistic that Monday's hailstorm will not have any long-term impact on the goal of retiring the three space shuttles after 14 more missions, the damage showed once again how unpredictable the launch schedule can be. Last year, the shuttle Atlantis was struck by lightning on the launchpad, triggering another significant delay.

Hale said technicians estimated that the hail left as many as 7,000 dings and divots in the external fuel tank's insulating foam, far more than any other hailstorm in Kennedy Space Center history. He said many of them are quite minor but all have to be examined and, if necessary, repaired.

Most of the hail hit the very top of the tank. Its foam covering is of special concern because a chunk broke off during Columbia's launch in 2003, hit and breached the shuttle's wing, and caused it to break up during reentry.