Lightning puts shuttle launch off for at least a day

NASA/Ken Thornsley
The shuttle Endeavour during sunnier days. Mission managers hope to launch the orbiter and its crew the evening of July 11. It's the fourth launch date for a mission that has had to cope with hydrogen leaks in June, which were fixed, and most recently, lightning strikes July 10 that were too close for comfort.

It's a tough weather break for the space shuttle Endeavour and its crew.

A violent thunderstorm moved over the Kennedy Space Center Friday around 3 p.m. Eleven bolts of lightning dropped down within 0.3 nautical miles of the launch pad. Of those, seven hit the orbiter's lightning protection system -- including a strike on the lightning mast that towers over the launch-pad service structure.

The concern: The closest strikes may have induced voltage spikes in circuits aboard the orbiter and in circuits that govern the pyrotechnic devices on the shuttle's twin solid-rocket motors.

The devices ignite the motors, blow the bolts attaching the boosters to the external fuel tank when the time comes to jettison the boosters, and fire motors that move the boosters away from the tank at separation time. Additional explosives are aboard to destroy the boosters if a malfunction makes that move necessary.

At a press briefing July 11, Mike Moses, who chairs the mission management team, said the group agreed to the delay to give engineers time to make sure the voltage spikes they saw from the lightning strikes didn't damage sensitive electronics aboard the craft.

"A lot of equipment has to be checked," he said.

NASA has tentatively rescheduled the launch for 7:13 P.M. Eastern Daylight Time July 12. But Mr. Moses acknowledged that if engineers felt they needed more time to check out the shuttle's and boosters' systems, the launch would get pushed off again.

Check out the video below to see what missions managers had to cope with from yesterday's thunderstorm.

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