NASA postpones space shuttle Discovery's launch due to gas leak

　　美国航天局11日发表声明说，由于连接“发现”号航天飞机及其外部燃料箱的液态氢传输管发生泄漏，“发现”号原定于当晚进行的发射将再次被推迟。

　　“发现”号最早定于2月12日发射，但由于燃料控制阀的安全隐患一直未完全排除，其发射日期被推迟。

　　“发现”号航天飞机目前已被运上佛罗里达州肯尼迪航天中心的发射台，它将运载7名宇航员前往国际空间站。在空间站停留期间，宇航员们将进行4次太空行走，在空间站右侧安装一个托架，并展开太阳能电池板。

　　The launch of U.S. space shuttle Discovery was postponed again on Wednesday due to a hydrogen gas leak found several hours before its scheduled liftoff, NASA said.

　　"The STS-119 launch was scrubbed at 2:37 p.m. EDT (1837 GMT) due to a hydrogen leak in a liquid hydrogen vent line between the shuttle and the external tank," NASA said in a statement.

　　The vent line is at the intertank region of the external tank and is the overboard vent to the pad and the flare stack where the vented hydrogen is burned off.

　　The launch team is resetting to preserve the option of attempting a Thursday night liftoff at 8:54 p.m. EDT (0054 GMT March 13) depending on what repairs are needed and what managers decide. The Mission Management Team is meeting at 5 p.m. Wednesday to discuss the issue, according to the statement posted on NASA's website.

　　Ground crews have begun to unload the liquid hydrogen fuel from the tank to lower the pressure so they can study the situation more. NASA space shuttles uses super-chilled liquid hydrogen propellant and liquid oxygen oxidizer to feed their three main engines during launch.

　　"Teams are going to get together and assess the repair options," said NASA spokesman Allard Beutel.

　　The leak was discovered at 2:15 p.m. EDT (1815 GMT), about two hours after ground crews began filling the shuttle's massive orange external fuel tank. The problem forced them to halt fueling immediately.

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