Orbital Sciences, a private Virginia company, says a major solar flare has forced it to postpone the launch of its unmanned rocket, the Antares, to supply the International Space Station (ISS).
The rocket will carry more than 1,200 kilograms of gear including science experiments, supplies, and hardware.
The launch had been scheduled for January 8 but company officials said it was postponed because increased levels of space radiation might damage the spacecraft's electronics.
Officials said they had yet to decide whether to attempt a January 9 launch.
The U.S. space agency, NASA, says increased solar activity poses no threat to the International Space Station.
The Antares launch was delayed earlier this week due to extremely cold temperatures in Virginia earlier this week.
There are currently six astronauts aboard the International Space Station, three of them Russian, two American, and one Japanese.
NASA announced on January 8 that the International Space Station will continue operations for an additional four years, or until 2024.
Based on reporting by AP and AFP