Because we had to go there for the Rosetta scientific objectives very far away -- four times the distance of the Earth to the sun -- and also at a much higher velocity than we could achieve with fuel, because we'd have to take six times as much fuel as the whole spacecraft weighed.
因为我们得去一个十分遥远的地方 去完成罗塞塔号的 科学目标—— 是地球到太阳距离的4倍—— 而且以一个我们用普通燃料 无法达到的速度。 因为我们得携带六倍于 航天器本身重量的燃料。