This story was updated at 9:10 a.m. EDT.
CAPE CANAVERAL, Fla. - The space shuttle Endeavour is "Go" to launch today, NASA said, after ground crews found no signs of damage from a lightning strike on Friday.
The crews completed all the necessary check outs of the vehicle's critical systems and cleared the shuttle for lift off this morning around 9:00 a.m. EDT (1300 GMT). Endeavour is now slated to blast off this evening at 7:13 p.m. EDT (2313 GMT) from Launch Pad 39A here at Kennedy Space Center.
The weather outlook for today has improved, with a 70 percent chance of favorable conditions, NASA said.
Endeavour's 15-storey external fuel tank is now due to begin filling with its liquid oxygen and liquid hydrogen propellant at 9:48 a.m. EDT (1348 GMT).
A violent electrical storm hit near Endeavour's perch atop Launch Pad 39A here at Kennedy Space Center, with 11 lightning bolts striking down on the pad. Though the shuttle did not take a direct hit, NASA feared the powerful electric charge in nearby lightning could have induced a current that may have damaged sensitive electronics aboard the orbiter.
"They concluded that there are no technical issues because of the lightning," NASA spokesman Allard Beutel said.
Endeavour's STS-127 mission has already been delayed twice by a potentially dangerous hydrogen gas leak from the shuttle's external fuel tank. Mission managers said they think that issue poses no threat after a repair was successfully tested last week.
The shuttle and its seven astronauts are slated for a 16-day construction mission to the International Space Station (ISS). Commander Mark Polansky will lead the crew in delivering an outdoor porch segment for the Japanese Kibo laboratory, some spare supplies, as well as a new long-duration station crewmember - NASA astronaut Tim Kopra - to the orbital outpost. Kopra is set to start a long-duration mission to the space station as a flight engineer on the outpost's six-man Expedition 20 crew.
Canadian astronaut Julie Payette and NASA astronauts Doug Hurley, Chris Cassidy, Tom Marshburn and Dave Wolf are slated to launch along with Polansky and Kopra on Endeavour. The spaceflyers plan an ambitious visit to the ISS with five spacewalks and complicated robotic work.
Endeavour's flight will be NASA's third shuttle mission of the year and the second to the ISS in 2009.
If crews do find damage, or are not able to complete the thorough checks required in time to start tanking on schedule, NASA may delay until Monday or later. Endeavour has until July 14 to launch before it must stand down to allow an unmanned Russian cargo ship to dock at the space station. If the mission does not get off the ground by then, NASA may negotiate with Russia for more time, or wait until the shuttle's launch window opens up 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 2:00 p.m. EDT (1800 GMT).