NASA delayed its first shuttle launch of the year for at least a week to allow time for engineers to review a potential problem with valves that keep the fuel tank pressurized, managers said on Tuesday.

The shuttle Discovery and seven astronauts had been scheduled to launch on Feb. 12 to deliver a final set of solar wing panels to the International Space Station.

The mission was postponed until at least Feb. 19 due to an issue with the valves that keep hydrogen fuel properly pressurized for the shuttle's three main engines.

"For the main engines to run correctly, the hydrogen tank has to be properly pressurized," said shuttle program manager John Shannon.

During NASA's last shuttle flight in November, a tiny piece of one valve broke off. That posed no threat to the shuttle but NASA wants more time to consider what would happen if a bigger piece of the valve's lip breaks off or if a similar event were to occur at a different time during liftoff.

"We want to make sure we got this right," Shannon said. "This has important consequences for us."

NASA also is analyzing impacts from excessive vibrations aboard the space station during an engine firing last month. The vibrations, which stressed some parts of the station, resulted from a software error made by the Russian flight control center to fire rockets and raise the station's orbit.

"We had to go and check to see if we had caused any damage to the space station," program manager Mike Suffredini told reporters.

Initial assessments indicate the $100 billion station, scheduled for completion next year, did not sustain any damage that would affect its operations during its planned 15-year lifetime.

The station, which has been under construction for 10 years, is a project of 16 nations. NASA has eight shuttle missions remaining to complete assembly.