Preparations are on track for Friday’s evening launch of the space shuttle Atlantis from Florida, despite a small chance of a scrub due to weather.

“We are tracking no issues at the moment,” said NASA test director Steve Payne.

However, there is a 30 percent chance that thunderstorms could encrouch within 20 nautical miles of the shuttle facility at NASA's Kennedy Space Center and delay launch.

“We do expect to see some afternoon thunderstorms in the area on launch day, but by launch time all that weather should move inland with the sea breeze,” said shuttle weather officer Kathy Winters.

“The weather looks reasonably promising for launch,” Winters added.

The seven-member STS-117 crew led by commander Frederick Sturckow arrived at KSC Monday evening and inspected the shuttle payload, which includes the S3/S4 truss segment and a new pair of solar arrays for the International Space Station (ISS).

The traditional call-to-stations will take place at 8:30 pm EDT tonight ( June 6, 0030 GMT) tonight, and T-43 countdown will begin at approximately 9 pm EDT (June 6, 0100 GMT).

Atlantis is set to lift off on Friday, June 8 at 7:38 pm EDT (2338 GMT). Atlantis has a clear launch window from June 8 to 12. If the shuttle fails to launch by June 12, it will stand down for four days to allow the scheduled launch of a Lockheed Martin Atlas rocket on June 14. The next launch opportunity will then be June 17.

During the 11-day mission, the STS-117 astronauts will perform up to four spacewalks to install the new space station parts. STS-117 crewmember Clay Anderson will also swap places with Expedition 15 flight engineer Sunita Williams, who has been living aboard the station since December. Williams and the rest of the STS-117 crew are scheduled to return to Earth on the afternoon of June 19.

The STS-117 mission was originally slated to begin on March 15, but was delayed due to hail damage to the orbiter's foam-covered external tank following a late-February storm.

“We’re relieved that we’re finally here. It’s been a long waiting period” Payne said. “The team is really excited, and we’re ready to get off the ground.”

Payne said that a planned strike by 570 United Space Alliance space shuttle program workers, which could begin as early as June 10, will not affect mission operations.

“We have a plan in place,” Payne said. “For those personnel, if it becomes an issue, we have personnel identified that can do the job and are certified and ready to go.”

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