CAPE CANAVERAL, Fla. — The launch of a SpaceX rocket ship with two NASA astronauts on a history-making flight into orbit was called off with less than 17 minutes to go in the countdown Wednesday because of thunderclouds and the danger of lightning. Liftoff was rescheduled for Saturday afternoon.

The spacecraff — designed, built and owned spacecraft by SpaceX — was set to blast off in the afternoon for the International Space Station, ushering in a new era in commercial spaceflight and putting NASA back in the business of launching astronauts from U.S. soil for the first time in nearly a decade.

But thunderstorms for much of the day threatened to force a postponement, and the word finally came down that the atmosphere was so electrically charged that the spacecraft with NASA astronauts Doug Hurley and Bob Behnken aboard was in danger of getting hit by a bolt of lightning.

“No launch for today — safety for our crew members (at)Astro—Doug and (at)AstroBehnken is our top priority,” NASA Administrator Jim Bridenstine tweeted, using a lightning emoji.