Clouds Aside, Shuttle Atlantis Set for Wednesday Launch

CAPE CANAVERAL, Fla. - A cloudy threat has grown for the plannedWednesday launch of NASA's shuttleAtlantis, though the weather outlook remains favorable for the spacecraft'sorbitalconstruction mission.

NASAshuttle weather officer Kathy Winters said Tuesday that the potential ofcumulus clouds within 10 nautical miles of Atlantis' Pad 39B launch site hereat the Kennedy Space Center (KSC) now give the orbiter a 70 percent chance ofrocketing toward the InternationalSpace Station (ISS) at 12:28:46 p.m. EDT (1628:46 GMT) tomorrow.

Those oddsalso include the possibility of isolated showers within 20 nautical miles of ashuttle runway to be used by Atlantis' STS-115 crew in the case of an emergencyjust after launch, Winters added.

Atlantis STS-115Mission managers discussed one last issue Tuesday - a minute hazardous gasreading in Atlantis' aft - which prompted questions among engineers at NASA's Johnson Space Center in Houston Texas. After a brief discussion, thematter was settled, NASA said.

"Thediscussion lasted five minutes, it was very short," said NASA launchintegration manager LeRoy Cain, who is chairing the preflight MissionManagement Team for Atlantis' STS-115 spaceflight, during a preflight briefinghere.

NASA launchdirector Michael Leinbach said sensors in Atlantis' aft picked up minuteamounts of gaseous liquid oxygen, which is used alongside liquid hydrogen topower the shuttle's fuel cells in orbit. The sensor reading is likely due to aslight misalignment between a ground system and the orbiter, though the twosystems are now detached, he added.

"This isnot a problem for us," Leinbach said, adding that he does not expect to see thereading again before launch. "This is not a constraint."

Atlantis ishauling a 17.5-ton,$371.8 million pair of new trusses and solar arrays to the ISS, where theywill be installed on the station's port side during three planned spacewalks.The mission is slated to last about 11 days.

Meanwhile,launch pad workers are hoping to roll back a shroud-like Rotating ServiceStructure - which protects NASA shuttles from poor weather - by 3:00 p.m. EDT (1900 GMT) before afternoonthunderstorms arrive in the area. The activity could be pushed up an hour at themost, NASA officials said.

Wayne Hale,NASA's space shuttle program manager, said that Atlantis' STS-115astronauts could gain two extra mission days if they launch Wednesday orThursday, which could ease a busy schedule that includes twoback-to-back spacewalks this weekend.

If needed,an extra day could be inserted on Flight Day 5 - which would be Sunday given aSept. 6 launch - to allow a focused inspection of Atlantis' heat shield, Halesaid.

While NASAis now routinely conducting a FlightDay 2 check of a shuttle's heat shield using a sensor-laden inspection boomthat adds an extra 50-foot (15-meter) reach to the orbiter's robotic arm. But afocused inspection to take an up-close look at certain areas will only be addedto the STS-115 crew's schedule if absolutely necessary, NASA officials said

"We don'thave that scheduled on the STS-115 timeline but we know that it is apossibility," Hale said of the focused inspections, adding that a second heatshield check is also scheduled near the end Atlantis' flight to scan fororbital debris damage. "There is a hope that, perhaps, we won't need to dothat."

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