Initial launch pad checks of the space shuttle Atlantis for its mission to service the Hubble Space Telescope should be getting under way during the first week of September, pending the resolution of orbiter/external tank umbilical mating difficulties.

Atlantis was to roll out to Launch Complex 39A as early as Aug. 30. But United Space Alliance technicians had difficulty extracting a jammed ground support system bolt used to initially align the hydrogen umbilical side of the tank's massive rigging structure with the orbiter's belly.

Engineers were evaluating whether there was any damage to the bolt hole on Atlantis before proceeding. Although Kennedy Space Center was closed for three days because of Tropical Storm Fay, the launch team still has about a week of margin to the planned Oct. 8 launch date.

But there are also external tank issues with the Endeavour flight hardware that will be rolled to Launch Complex 39B to be ready for any rescue of the Atlantis crew during its Hubble servicing mission, which will have no International Space Station safe haven capability. While lifting the 155-foot tall Lockheed Martin tank to the vertical position in the Vehicle Assembly Building, several technicians heard a noise that sounded like a piece of loose hardware falling inside the sealed tank.

If there is loose debris, such as a small bolt, inside the tank, it could have catastrophic consequences during launch, if not for rescue, then on its November station mission.

Engineers have been using X-rays and other means to assess whether there is any debris inside and whether internal filtering systems would be able to safely catch it before it could be sucked into a main engine, causing an explosion. But the issue must be resolved before the Atlantis Hubble mission is approved for launch.