In a semiheavy water molecule , one hydrogen atom is replaced with a heftier version called deuterium .

在半重水的水分子中，一个氢原子被一个称之为氘的氢原子的同位素所取代。

Ocean water does have more deuterium than water in the earth 's mantle .

海水含有的重氢含量同样比地幔的重氢含量高。

If such a design can be successfully used for a starship engine , then a source of deuterium can be sought closer to home .

如果这样一个设计可以成功的用于星际飞船发动机，那么氘能源可以在离家更近的地方找到。

Alternatively , a means might be found to put the neutrons from pure deuterium fusion to good use .

作为可替代的一种方法也许被创建用于从单纯的氘聚变中取得中子为了有效的使用。

Because if comets battered the moon , they probably hit the earth , too . Ocean water does have more deuterium than water in the earth 's mantle .

因为如果彗星曾重重撞击过月球，那它们很可能也造访过地球，海洋里的水的确比地幔的水含有更多氘。