NASA managers on Wednesday unanimously picked Aug. 27 for the first attempt to launch the space shuttle Atlantis on a mission to resume construction of the international space station — but two precariously attached bolts securing a crucial antenna could delay those plans.

Engineers suspect that two of the bolts are too short on the KU-band antenna, which transmits images and other essential data between the space shuttle and Mission Control.

They want to make sure the bolts are secure enough so that the antenna doesn't fly off while in the payload bay during a launch, which could cause catastrophic damage.

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"We're not going to fly if we think there's a possibility the antenna will come off," said NASA Administrator Michael Griffin.

Atlantis has flown with those bolts without trouble since they were first installed two decades ago.

The problem was discovered last week, after Atlantis was rolled to the launch pad, when a review of paperwork on bolts on NASA's three space shuttles was ordered because a related problem was found in Discovery.

NASA officials likely won't decide until this weekend whether to leave the bolts in place or change them in a tricky swap-out at the launch pad.

Technicians would have to build scaffolding on top of a platform six stories off the ground in order to change out the bolts with the shuttle vertical on the launch pad. A swap-out probably would take NASA the two spare days it has in the schedule.

"Imagine operating on a surfboard that is tied down at one end, sticking out over a six-story balcony," said Wayne Hale, space shuttle program manager. "You have all kinds of implications that you would really rather not do because of the location and access."

A two-day meeting of NASA's top managers wrapped up at the Kennedy Space Center Wednesday with a poll on whether to go ahead with the launch.

NASA associate administrator Bill Gerstenmaier called the poll "unanimous," but he said representatives from the Johnson Space Center and the Marshall Space Flight Center voiced concerns about the current design of ice-frost ramps on the external fuel tank.

These wedge-shaped brackets run up and down the tank holding pressurization lines in place, and they have been known to shed foam in the past.

Foam falling off space shuttle Columbia's external tank doomed the vehicle and its crew in 2003.

"Their opinion is they would like the ice-frost ramps redesigned as soon as possible," Gerstenmaier said.

At an identical meeting before the successful flight of space shuttle Discovery last month, NASA's top safety officer, Bryan O'Connor, and chief engineer, Chris Scolese, refused to endorse the launch until the ice-frost ramps were redesigned.

This time around, O'Connor and Scolese didn't object to a launch attempt.

O'Connor scrawled in a note, on a report approving the launch, that he understood Griffin was accepting the possibility of a vehicle loss with the current design.

Griffin has said that the foam problem may pose a risk to the vehicle, but that there is no danger to the crew because they could take haven at the space station until another shuttle retrieved them.

NASA is developing a new external tank design that involves placing titanium over the ice-frost ramps, but that probably won't be introduced until February or March.