NASA postponed the launch of space shuttle Endeavour's STS-127 mission Wednesday because of a leak associated with the gaseous hydrogen venting system outside the shuttle’s external fuel tank.

Endeavour's next launch opportunity is July 11. This date comes after the end of an orbital sun-angle condition called a beta angle cut-out, which occurs between June 22 and July 10. The cut-out creates a thermal condition that prohibits shuttle and space station docked operations.

Space Shuttle Mission: STS-127

The gaseous hydrogen venting system is used to carry excess hydrogen safely away from the launch pad. Wednesday's leak is similar to one that prevented Endeavour's launch on June 13.

The 16-day mission to the International Space Station will feature five spacewalks and complete construction of the Japan Aerospace Exploration Agency's Kibo laboratory. Astronauts will attach a platform to the outside of the Japanese module that will allow experiments to be exposed to space.

Mission Commander Mark Polansky, who has a Twitter account named Astro_127, can be followed online at:

http://www.twitter.com/Astro_127

For information about NASA TV streaming video, downlink and schedule information, visit:

http://www.nasa.gov/ntv

For the latest information about the STS-127 mission and its crew, visit:

http://www.nasa.gov/shuttle
For information about the International Space Station, visit:

http://www.nasa.gov/station