(CNN) -- NASA postponed the launch of the space shuttle Endeavour early Wednesday because of a liquid hydrogen leak.
Another gas leak has forced NASA officials to scrub Wednesday's planned space shuttle launch.
It is the same type of leak that caused the postponement of an earlier launch from Kennedy Space Center in Florida.
On June 13, a leak was detected in the gaseous hydrogen venting system outside the shuttle's external fuel tank, the space agency said. The system is used to carry excess hydrogen safely away from the launch pad. Officials said the seal around the system had to be replaced.
Wednesday's morning leak was in the same area, the space agency said.
The shuttle, carrying seven astronauts, was scheduled to launch at 5:40 a.m. Wednesday for a 16-day mission to the International Space Station. Five spacewalks are planned for the crew after the shuttle docks.
The mission's primary goal is to install what amounts to a porch in space. Endeavour will carry in its cargo bay two platforms of the Japanese Kibo Laboratory, which is already part of the space station.
One platform rides up and back on the shuttle, while the other will stay permanently fixed to the Kibo laboratory for scientific experiments that require exposure to 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 next opportunity for launch is July 11, the space agency said.