Shuttle officials said there have been no technical problems so far as countdown continued ahead of Friday's 7:38 pm (2338 GMT) scheduled liftoff at the Kennedy Space Center on Florida's Atlantic coast.

The weather was not expected to be a problem, with launch meteorologist Kathy Winters upgrading the chance of good weather conditions to 80 percent.

The area frequently sees afternoon thunderstorms, but Winters said they are expected to stay to the west of the space center and not threaten the launch.

Atlantis originally was scheduled to launch in March, but a freak hail storm damaged the shuttle's massive external fuel tank as the orbiter stood on its Florida launch pad, forcing NASA to bring it back to its hangar for repairs.

The seven shuttle astronauts - all American men - arrived in Cape Canaveral Monday evening from their base at the Johnson Space Center in Houston, Texas, as they prepare for the 21st shuttle mission to the International Space Station.

During their 11-day mission, they will install a new, 16-tonne truss segment on the ISS and deliver a third set of solar panels as well as batteries for the orbiting laboratory.

Three spacewalks lasting six and a half hours each are planned on the fourth, sixth and eighth days of the mission.

NASA plans at least 13 shuttle missions to finish the 100-billion-dollar station by 2010, when the US space agency retires its three-shuttle fleet.

earlier related report
STS-117 Launch One Day Away At this morning's Countdown Status Briefing, NASA Test Director Steve Payne reported that after many months of hard work Atlantis is ready to launch. External tank inspections are in process and there are no issues being tracked.

Upon completion of all checks and inspections the access platforms will be retracted. The xenon lights will be lit, brightly illuminating the space shuttle, which can be seen from miles away.

"We're ready to fly tomorrow," said Payne.

Roy Worthy, external tank and solid rocket booster vehicle manager, described the multitude of repairs performed on the external tank and thanked the hundreds of workers who labored days on end to complete the task.

STS-117 Payload Manager, Robbie Ashley, reported that the payload was loaded into the orbiter's payload bay this week and everything is ready and secured for launch.

Kathy Winters, shuttle weather officer said there is now only a 20-percent chance that weather would affect the launch. A high pressure ridge has entered the area and although the typical Florida afternoon storms may develop, they should be west of Kennedy Space Center and not an issue at launch time.

The forecast for tomorrow morning is for light winds and a zero percent chance of weather prohibiting the loading of propellants into the external tank.

Commander Rick Sturckow and Pilot Lee Archambault have been practicing landings in the Shuttle Training Aircraft and the entire crew is making final preparations for tomorrow's liftoff.

Transfer of the hydrogen and oxygen reactants were completed this morning. These reactants will be used by Atlantis to generate power during the mission. The umbilical unit was secured once the loading was accomplished.

The launch pad's rotating service structure is scheduled to roll away from Atlantis at 10:30 p.m. tonight. When in place, the giant revolving enclosure is used to install payloads into the orbiter's cargo bay and provide protection from inclement weather.

On Friday, launch day, propellant loading is set to begin at about 9:30 a.m., with the pumping of more than 500,000 gallons of liquid oxygen and hydrogen into the vehicle's orange external tank.

NASA TV coverage of the launch and live launch countdown coverage from NASA's Launch Blog will begin at 1:30 p.m. EDT Friday.

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STS-117 Mission
Space Shuttle News at Space-Travel.Com