Humans,he said, are astronauts on Spaceship Earth.

VOA: special.2010.05.30

If you escape the pull of gravity, your spaceship will be off, won't be orbiting the Earth.

如果你完全脱离重力,太空船早就飞得没影了,而不是在轨道上运行

耶鲁公开课 - 基础物理课程节选

People must live on Earth just as astronauts live in a spaceship.

VOA: special.2010.05.30