 How does Sattell hope to get rid of Pop?
There is nothing like it on Earth, of course. Pop lived in it all alone, and in his spare time he worked industriously at recovering some missing portions of his life that Sattell had managed to take away from him. Sattell got the shakes when he thought of Pop, and Pop rather probably knew it. Pop had come back to consciousness in a hospital with a great wound in his head and no memory of anything that had happened before that moment. All of which happened back on Earth and a long time ago. And a cover of insulating moondust with vacuum between the grains kept even air frozen solid, though in sunlight. He'd started to follow Sattell knowing what had happened to his wife and children, but it was hearsay only. When Sattell fled to another continent, Pop followed because he had some distinct memories of his wife—and the way he'd felt about her—and some fugitive mental images of his children. When Sattell frenziedly tried to deny knowledge of the murder in Tangier, Pop had come to remember both his children and some of the happiness of his married life. Even when Sattell—whimpering—signed up for Lunar City, Pop tracked him. If so, Sattell had profited by less than two days' pay for wiping out everything that Pop possessed. The sun rose very, very slowly in what by convention was called the east.
 Escaping on board a secondhand lunar tour vessel
 Luring him down into the Big Crack and killing him  Hiring an assassin from a neighboring planet  Blowing up the shack near the edge of the Big Crack  Escaping on board a secondhand lunar tour vessel