A U.S. company is delaying a space station delivery mission because of a major solar flare.

Orbital Sciences Corp.'s unmanned rocket, the Antares, was supposed to blast off Thursday from Virginia with a capsule full of supplies and experiments. But on Wednesday, company officials took the unusual step of postponing the launch for fear solar radiation could doom the rocket.

Orbital Sciences' chief technical officer, Antonio Elias, said solar particles might interfere with electronics equipment in the rocket, and lead to a launch failure.

The solar flare peaked Tuesday afternoon. But more solar disturbance is expected. Officials will decide late Wednesday afternoon whether to attempt a Thursday launch or wait for the sun to settle down.

NASA says the solar activity poses no threat to the six men aboard the International Space Station. Satellites also should be safe from the sun's latest outburst, Elias noted. The Cygnus capsule aboard the rocket, for example, is built to withstand radiation from solar flare-ups.

ISS lifetime extended until at least 2024

Also on Wednesday, NASA said the White House was poised to announce an extension of the space station's lifetime until at least 2024. The previous end-of-life date was 2020. That's good news for scientific research aboard the orbiting lab, said Bill Gerstenmaier, chief of NASA's human exploration and operations.

NASA is using two private companies — Orbital Sciences and SpaceX — to keep the space station stocked. The space agency turned to private industry for help following the space shuttle program; the last shuttle flight was in 2011.

Russia, Europe and Japan also periodically launch supply ships.

The Cygnus was supposed to fly in December, but a breakdown in the space station's cooling system required repairs by spacewalking astronauts. The repair job, which was completed on Christmas Eve, bumped the supply mission to this week. Then frigid temperatures forced a launch delay from Tuesday to Wednesday.

Frank Culbertson, an executive vice president Orbital Sciences, said the delays can be frustrating, but he pointed out there's nothing wrong with the rocket itself.

The first space station piece rocketed into orbit in 1998.