From their work on bicycles, they already knew control and balance would be critical, so they tested their ideas with unmanned gliders.

从他们在自行车上的工作，他们已经知道控制和平衡是至关重要的，所以他们用无人滑翔机测试了他们的想法。

But this is what it looks like from the third stage of the rocket looking at the unmanned glider as it heads into the atmosphere back towards Earth.

但这正是从火箭发射的第三阶段上看到的无人操纵滑翔机的样子。它冲进大气层返回地球。