Complex sentence: An alien voice states their actions were neither benevolent nor malevolent; the goal was to prevent Earthmen from penetrating their planet and making the Moon habitable was a means to keep them away.
Split into simpler sentences: An alien voice states their actions were neither benevolent nor malevolent. Their goal was to prevent Earthmen from penetrating their planet&mdashh; making the Moon habitable was the means to keep them away.