We can imagine a spacecraft carrying a big area of him film to collect solar energy, with an ion?jet engine to produce thrust powerful enough to boost a spacecraft to a speed of 160 km a second.

• 我们可以设想一艘航天器，它装载着收集太阳能的巨大薄膜，并载有一个能产生强大推力足以使航天器加速到每秒160公里的离子喷气发动机。