Cape Canavarel, Fla. ? Rain in the forecast threatened to delay the last space shuttle launch, set for today, and a lightning strike near the pad briefly caused a flurry of concern at NASA before engineers concluded the spaceship was OK.

The lightning bolt hit a water tower about 500 feet from the launch pad at midday Thursday, the space agency said. Technicians hurried out to check for electrical problems, but a review board ruled out any damage.

Over the years, lightning has struck on or near the launch pad occasionally, delaying a few launches but causing no damage.

The forecast for today, meanwhile, looked dismal, with only a 30 chance of acceptable weather at launch time, 10:26 a.m. CDT

NASA is closing out its 30-year space shuttle program to take aim at asteroids and Mars, destinations favored by the White House. Private companies will take over the job of hauling cargo and crews to the International Space Station, freeing NASA up to focus on points beyond.

Rain or shine, hundreds of thousands of people are expected to jam the area for the launch.