BEIJING, March 22 (Xinhuanet) -- NASA won't be able to launch the space shuttle Atlantis -- originally scheduled for blast-off last week -- until May and it's Mother Nature's fault.

    NASA managers announced Wednesday the launch was postponed to give technicians more time to assess damage to the shuttle's external full tank after golf-ball-size hail caused thousands of dings on the tank's foam insulation as the shuttle sat on the launch pad last month.

    The space shuttle was rolled off the launch pad and sent back for repairs to the Vehicle Assembly Building. Technicians have spent two weeks erecting scaffolding around the external tank and sanding down some parts of the foam insulation.

    Bill Gerstenmaier, associate administrator for space operations, said NASA managers probably would wait until April 10 before deciding whether to use the current tank use another tank.

    "We can get some more analysis done; then we will have enough data to make a good decision," Gerstenmaier explained.

    If NASA decides to use the current tank, Atlantis might be ready for liftoff in the latter part of a launch window that lasts until May 21, said Wayne Hale, space shuttle program manager.

    But if NASA decides to use another tank, that would push back the launch to no earlier than June 8, when the next window opens. Between those dates, the sun's position is unsuitable for the shuttle to be docked at the station.

    Atlantis¡¯liftoff has to be after a Russian Soyuz vehicle completes a mission to the international space station in the first part of April.

    Repairing Atlantis' tank will require technicians to respray foam at the top of the tank, which was heavily damaged in the hailstorm. To make sure the repair would be safe to fly, detailed engineering assessments and tests will have to be conducted prior to launch, said NASA spokesman Kyle Herring.

    The insulating foam is of special concern to NASA since a chunk of it flew off during space shuttle Columbia's launch in 2003 and struck the orbiter. The damage allowed fiery gases to penetrate Columbia during re-entry, breaking up the craft and killing its seven astronauts.

    NASA redesigned the external tank, removing large amounts of foam, before last year's three successful shuttle missions. The space agency plans another design change to the tank before the shuttle program ends in 2010.

    (Agencies)