Lightning Bolt Jolts Shuttle Launch Pad

NASA postponed today’s scheduled launch of the space shuttle Atlantis for at least 24 hours while engineers looked into possible damage to the orbiter from a massive lightning strike.

During a thunderstorm Friday, a bolt of lightning measured at 100,000 amps struck the lightning mast above the shuttle on Launch Pad 39B. It is believed to be the largest strike ever to hit the launch site.

Although the mast did its job in preventing the lightning from hitting the orbiter directly, NASA officials said Saturday that they were concerned that electricity in the atmosphere around the pad, on a peninsula in the Atlantic, could have damaged critical control systems.

“We did see a couple of indications that make us want to look at the ground and flight systems and make sure we’re able to fly,” said LeRoy E. Cain, chairman of NASA’s Mission Management Team, which has final authority over launch decisions.

At least two instrument readings went out of line after the lightning strike, worrying safety engineers. One was in an electrical bus that supplies power to certain systems on the orbiter, which carries the crew. The other was in the hydrogen vent arm, which allows excess hydrogen to boil off just prior to launch. The arm is designed to swing free of the shuttle less than a minute before liftoff.

Both must operate correctly for a successful launch, which is why NASA took the unusual step of scrubbing today’s launch a full day ahead of time. NASA officials said they could not predict the chances of launching on Monday.

“We know just enough to know we don’t know enough” about the possible damage, Cain said. “We need to let the [engineering] folks go off and look at the data.”

The weather outlook for Monday is improving. Even without the lightning strike, today’s launch had looked uncertain due to thunderstorms. The storm front is expected to move off by Monday.

Kennedy Space Center is in what is known as Lightning Alley -- a corridor from Tampa to Titusville, Fla., said to be the capital for lightning storms in the United States, and possibly the world.

Even by those standards, Friday’s storm was a big one. The bolt that struck the tower on the launch pad produced enough electricity to light up a good-sized suburban housing development, according an aerospace engineer speaking at a news conference Saturday.

The upcoming shuttle mission, known as STS-115, will be one of the most challenging in the shuttle’s recent history. Atlantis will carry aloft a 17-ton truss to serve as the backbone for a new wing of the International Space Station. Along with the truss, new solar arrays will be attached to supply more power to the station. When unfurled, the truss and solar panels will measure 240 feet in length.

STS-115 will be the first mission to carry construction materials since the shuttle Columbia tragedy in 2003.

NASA is racing to finish construction of the half-built space station before the shuttle program is phased out in 2010 in favor of a new spacecraft that will carry astronauts back to the moon and, NASA hopes, to Mars.