Once again, thunderstorms have forced a delay for the launch of the U.S. space shuttle Endeavour.

It is the second evening in a row that NASA has canceled the liftoff due to weather.  The latest postponement Monday comes after two abortive attempts last month because of hydrogen fuel leaks.

The space agency has until Tuesday or Wednesday to get Endeavour into orbit and up to the International Space Station.  Otherwise, flight managers have to wait until near the end of July to make way for a Russian supply ship to launch and dock at the station.

The seven-member shuttle crew plans to conduct a two-week mission to deliver the final piece of a Japanese laboratory known as Kibo.  Kibo means "hope" in Japanese.

Kibo amounts to a porch to be installed on the space station.  It is designed to expose experiments to the vacuum of space.

Endeavour will carry astronaut Timothy Kopra to take the place of Japan's Koichi Wakata, who has been on the space station since March.  The shuttle's payload also includes batteries and spare parts for the space station.  

Some information for this report was provided by AP and Reuters.