The insulating foam prevents ice from forming on the tank when it is filled with 500,000 gallons (1.9 million liters) of supercold liquid hydrogen and liquid oxygen before liftoff.

为什么会脱落呢？ 在航天飞机被发射出去之前，它的外部燃料箱里会装满50万加仑（合190万公升）的极冷液态氢和液态氧。

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Cameras and an inspection team spotted the bat clinging to the side of Discovery?s 15-story external tank as it was being fueled with propellant ? super-cold liquid hydrogen and liquid oxygen.

摄像机和一个检查小组捕捉到了这只蝙蝠的图像，它紧紧地贴在发现号15层的外置燃料箱上，当时正在进行灌注燃料（超低温的液氢和液氧）的程序。

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This device helps vent gas that boils off from the liquid oxygen tank, and also bathes the top of the tank in warmed nitrogen to prevent ice from forming.

这个装置有助于排除液氧燃料箱蒸发的气体，并且它还可以用加温氮气笼罩箱顶，以防结冰。

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