A middle layer of nickel, which gives the bots magnetic polarity, so they can be pulled through wastewater with magnets.

中间的镍层提供磁极性，这样在磁力作用下机器人可以从废水中脱离。

The Pioneer plaque gives a hint in the form of a basic diagram of a hydrogen atom, the magnetic polarity of which flips at regular intervals, with a frequency of 1,420MHz.

先驱牌匾以氢原子基本图的形式给出了一个提示，氢原子的磁极按一定的间隔翻转，频率为1420mhz。