It is the oldest and longest-serving vehicle in the U. S. space agency's shuttle fleet.

发现号是美国太空总署航天飞机机队里最老、服役年头最长的一架航天飞机。

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It is the oldest and longest-serving vehicle in the U. S. space agency's shuttle fleet.

发现号是美国太空总署航天飞机机队里最老、服役年头最长的一架航天飞机。

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