Atlantis is poised to blast off Friday on the very last shuttle flight. Thunderstorms, however, are threatening to keep Atlantis grounded.
On Thursday, heavy rain and storms pelted the Florida launch site. Early in the afternoon, NASA reported a possible lightning strike within one-third of a mile from the pad. Technicians are checking for damage to the electrical systems.
The shuttle has yet to be fueled for its historic mission. And the four astronauts won't board until Friday.
Launch time on Friday is 11:26 a.m.