The 322-foot (98-meter) Space Launch System rocket is the most powerful ever built by NASA. It's poised to send an empty crew capsule into lunar orbit, a half-century after NASA's Apollo program, which landed 12 astronauts on the moon.

Astronauts could return to the moon in a few years, if this six-week test flight goes well. NASA officials caution, however, that the risks are high and the flight could be cut short.

In lieu of astronauts, three test dummies are strapped into the Orion capsule to measure vibration, acceleration and radiation, one of the biggest hazards to humans in deep space. The capsule alone has more than 1,000 sensors.

Officials said Sunday that neither the rocket nor capsule suffered any damage during Saturday's thunderstorm; ground equipment also was unaffected. Five strikes were confirmed, hitting the 600-foot (183-meter) lightning-protection towers surrounding the rocket at NASA's Kennedy Space Center. The strikes weren't strong enough to warrant major retesting.