[MilAir] The story about the Shuttle lightning strike

[AllanStern at aol.com]

Lightning Hit Delays Launch.
Big charge may have zapped circuitry
BY  TODD HALVORSON FLORIDA TODAY 
 
Sunday update: Launch delayed to Tuesday because of the issue noted below. 
 
CAPE CANAVERAL - An extensive analysis of the largest launch-pad lightning  
strike in NASA history will wrap up today before agency managers decide whether 
 to try to launch shuttle Atlantis and six astronauts on Monday.
 
With liftoff tentatively set for 4:04pm EDT Monday [now Tues, 3:41pm  EDT], 
NASA will determine if any additional testing is needed in the wake of a  
powerful thunderbolt that struck the lightning mast on the top of the shuttle's  
36-story launch tower.
 
About 100,000 amps of electricity shot down three-quarter-inch wires that  
run from the mast to the ground, where sensors measure the voltage output.
 
That's five times the electrical current in an average stroke of lightning.  
It's enough electricity to simultaneously operate 83,333 color television 
sets.  Or about 5,000 times the amount of current that could cause a person to 
stop  breathing.
 
Said senior NASA launch manager LeRoy Cain: "It's a lot of current."
 
NASA intended to launch Atlantis and its ISS construction crew at 4:30 pm  
today.
 
The lightning bolt struck the launch tower Friday afternoon as a half dozen  
violent thunderstorm cells swept from Tampa through Titusville and then 
Kennedy  Space Center.
 
NASA decided to postpone the launch Saturday after preliminary analyses  
showed that the thunderbolt might have damaged an electrical bus that  distributes 
power from one of the shuttle's three fuel cells.
 
Data also indicated that the strike might have fried circuitry that sends  
computer commands to small explosive devices designed to separate a hydrogen  
vent arm from the shuttle's 15-story external tank at liftoff.
 
Serious damage could be done to the launch pad and the shuttle if the  
pyrotechnic charges failed to fire.
 
Such a failure also could be catastrophic.
 
The delay gave engineers an extra day to make certain that the shuttle and  
its $372 million cargo -- a new station truss segment with two massive solar  
wings -- are ready to fly.
 
"We know just enough to know that we don't know enough," Cain said. "We  need 
to let folks go off and look at their data, and that's what we're going to  
do."
 
Another factor in the decision: the weather outlook over the next three  days.
 
The high-pressure ridge steering thunderstorms into central Florida over  the 
past several days is not drifting north as quickly as meteorologists had  
expected.
 
Consequently, forecasters said there was a 60 percent chance that  
thunderstorms, rain or electrically charged clouds would sweep into the KSC area  again 
today, forcing NASA to scrub a launch attempt.
 
The system is expected to move north by early Monday, taking the stormy  
weather with it. Clearer conditions are predicted, and forecasters say there is  
an 80 percent chance the weather will be acceptable for flight either Monday or 
 Tuesday.