CAPE CANAVERAL, Fla. - NASA engineers are poring over systems that control the space shuttle Atlantis' twin solid rocket boosters to determine whether to once more delay the orbiter's planned liftoff due to a powerful lightning strike at the launch pad, agency officials said Sunday.
Atlantis and its six-astronaut crew could still launch toward the International Space Station (ISS) as planned on Monday at 4:04:14 p.m. EDT (2004:14 GMT), but if more invasive booster checks are needed a delay to Tuesday or beyond is possible, NASA spokesperson George Diller told SPACE.com.
"We have not officially made a decision to go for Tuesday," Diller said. "It is a developing story."
Atlantis' STS-115 mission to deliver a $371.8-million set of new trusses and solar arrays to the ISS has already been delayed one day - from a planned Sunday launch - due to a powerful bolt of lightning that struck the orbiter's Pad 39B launch site Friday. The 100,000-amp bolt of lightning struck the pad's lightning protecting system, though engineers registered a small spike in one of the Atlantis' three electrical buses and a larger surge in a system that allows a hydrogen vent arm to pull free from the orbiter's external tank just before launch.
STS-115 Mission Management Team chairman LeRoy Cain opted Saturday to scrub the planned space shot for 24 hours to allow the system checks necessary to determine whether other orbiter or launch pad systems were affected by the lightning strike, which is considered the strongest ever seen at a NASA launch pad.
While engineers have good data on Atlantis' systems during the strike - it was that data that showed the electrical bus spike - they do not know whether the shuttle's two solid rocket boosters experienced a similar glitch since they were powered down at the time, NASA spokesperson Bruce Buckingham said.
Engineers want to determine whether the electronics associated the boosters' explosive pyrotechnics, used to separate the rockets from the launch pad at liftoff and from Atlantis' external tank about two minutes into flight, NASA officials said.
Diller said engineers are working to determine whether they have enough data on orbiter's solid rocket booster systems. Based on that assessment, mission managers will decide whether Monday is still a viable launch day or whether to push to a Tuesday flight plan.
Cain's management team assembled in an impromptu meeting late Saturday night, and will meet again today for an update on that work.
Weather forecasts for both Monday and Tuesday are favorable, with an 80 percent chance of good launch conditions, shuttle weather officials have said.
NASA's window to launch Atlantis extends through Sept. 7, when the agency plans to stand down to allow a Russian Soyuz spacecraft to launch toward the ISS on Sept. 14 with a new station crew aboard.
A press briefing is expected some time around midday, NASA said.
An added complication in NASA's Atlantis launch preparations is Hurricane Ernesto, which grew from a tropical storm into a full-blown hurricane one day earlier than expected today, with current forecasts predicting a path bound for the west coast of Florida later this week.
Space shuttles are typically rolled back into the safe shelter of the agency's massive, 52-story Vehicle Assembly Building if flight controllers expect winds in excess of 70 knots at the launch pad, according to NASA documents.
NASA continues to watch Hurricane Ernesto's development and path to determine if it will impact launch preparations should an extended flight delay become necessary, NASA spokesperson Lisa Malone said.
Today's planned midday status update will be held on NASA TV. You are invited to follow the briefing using SPACE.com's NASA TV, which is available by clicking here.
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