This story was updated at 11:44 a.m. EDT.
CAPE CANAVERAL, Fla. - The oft-delayed space shuttle Endeavour will have to wait at least one more day to launch while NASA investigates whether lightning strikes near the launch pad yesterday caused any damage.
No positive signs of harm to Endeavour have yet been found from the violent lightning storm Friday afternoon, but mission managers called for a 24-hour delay to investigate before resuming the countdown to lift off.
"We need to be 100 percent confident that we have a good system across the board," said Mike Moses, Endeavour's mission management team chairman, during a Saturday briefing. "We've seen nothing so far that indicates anything was actually affected by the lightning strike. But we have to check and that?s what takes time."
Thunderstorms have lately plagued the seaside region of the Kennedy Space Center here, and sensors counted 11 lightning strikes within about 0.3 miles of Endeavour's perch on Launch Pad 39A Friday.
Although no lightning directly impacted the orbiter, fuel tank or solid rocket boosters (SRBs), a near enough strike could have induced a strong current that could disable the sensitive electronics in the orbiter, or the pyrotechnics in the SRBs.
"The concern is mostly in those pyrotechnic systems," Moses said. "There's a lot of things that have to go right. That?s why we need to double check everything."
Mission managers hope an extra day will be enough time to thoroughly check out Endeavour.
"I have high confidence we'll get there in 24 hours, but I certainly cannot guarantee it," Moses said.
If no serious signs of damage are found, Endeavour could try to launch again as early as Sunday at 7:13 p.m. EDT (2313 GMT) on its planned 16-day construction mission to the International Space Station. The weather outlook is slightly better for Sunday than today's forecast, with a 60 percent chance of favorable conditions expected.
Endeavour's STS-127 mission has already been held at the ground after a persistent leak of gaseous hydrogen twice prevented the shuttle from lifting off. NASA has said the leak, a potentially dangerous gas flow from a vent pipe leading off the vehicle's 15-storey external tank, has been fixed.
After a thorough investigation, ground crews traced the problem to a misaligned plate on the tank. NASA repaired the plate and successfully tested the system last week. Mission managers said they're confident the issue won't pose a problem anymore.
Commanded by veteran shuttle flyer Mark Polansky, Endeavour?s STS-127 mission will launch toward the International Space Station carrying vital spare parts and a Japanese-built porch for the outpost?s massive Kibo laboratory. The marathon 16-day mission will also ferry rookie NASA astronaut Tom Kopra to the station to replace Japanese astronaut Koichi Wakata, who has lived aboard the orbiting lab since late March. Wakata is Japan's first long-duration astronaut and has watched over his country?s $1 billion Kibo laboratory at the station.
Set to launch spaceward aboard Endeavour with Polansky and Kopra are STS-127 pilot Doug Hurley and mission specialists Chris Cassidy, Julie Payette, Tom Marshburn and Dave Wolf. Payette represents the Canadian Space Agency, while the rest are NASA astronauts. Five spacewalks are planned.
Kopra is beginning a three-month mission to the space station as a flight engineer on the outpost?s six-man Expedition 20 crew. He will join two Russians, another American and astronauts from Belgium and Canada on what is the station?s first full six-person crew.
Endeavour?s 16-day mission will mark NASA's third shuttle flight of the year and the second space station construction flight of 2009.
If Endeavour is unable to launch Sunday, a third attempt is possible on Monday, with a 70 percent chance of good weather. NASA has until July 14 to launch the shuttle before standing down to allow avoid a traffic conflict with an unmanned Russian cargo ship also due at the space station this month. If the mission is unable to launch by then, NASA can try again on July 27.
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SPACE.com is providing continuous coverage of STS-127 with reporter Clara Moskowitz at Cape Canaveral and senior editor Tariq Malik in New York. Click here for mission updates and SPACE.com's live NASA TV video feed. Live launch coverage begins at 2:30 p.m. EDT (1830 GMT).