 How does Sattell hope to get rid of Pop?
Sattell got the shakes when he thought of Pop, and Pop rather probably knew it. 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. If so, Sattell had profited by less than two days' pay for wiping out everything that Pop possessed. But then an event occurred which bore directly upon Pop Young and Sattell and Pop Young's missing years. But Sattell undoubtedly dealt with it fully in his desperate writings back to Earth.
 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