NASA scrubs Saturday launch of space shuttle Endeavour

(CNN) -- A gaseous hydrogen leak on the space shuttle Endeavour forced NASA to cancel Saturday's planned launch, the space agency said.

NASA halted fueling of the shuttle Saturday morning after detecting the leak, associated with the gaseous hydrogen venting system outside the shuttle's external fuel tank, NASA said. The system is used to carry excess hydrogen safely away from the launch pad.

Shuttle managers will assess the leak and meet at 2 p.m. ET Sunday to discuss what steps to take next, including setting a new launch date, NASA said. They planned a news conference after the meeting, the space agency said.

The earliest the shuttle could be ready to launch now is Wednesday, NASA said, but there is a conflict on that date with the scheduled launch of the Lunar Reconnaissance Orbiter/Lunar Crater Observation and Sensing Satellite.

Endeavour, carrying seven astronauts and a key component for Japan's Kibo science laboratory, is scheduled for a mission to the International Space Station. View behind-the-scenes images of Endeavour »

Five spacewalks are planned for the crew after the shuttle docks with the station for a planned 16-day mission. View an interactive of what mission will do in space »

The Kibo science lab, also called the Japanese Experiment Module, is Japan's first human space facility, more than 20 years in the making. The bus-sized, 32,000-pound module will be the largest lab at the space station. Watch John Zarrella's report from the Kennedy Space Center in Florida »

Kibo means "hope" in Japanese.

All About Space Shuttle Endeavour • NASA