Heinlein had been collecting ideas for a 20,000-word novelette about a pioneer Scout on another planet, with the intriguing twist that he would actually have to create his own soil in order to farm it. Ginny suggested that, as his last boys’ book was set on Mars (Red Planet), this should be the next step farther out—Jupiter. He realized that he could make the novelette idea work also as a book, and that it was worthwhile to cultivate Scribner, even after the aggravating and drawn-out fight over social philosophy in Red Planet. “… Despite recent and current headaches, Scribner’s has treated me well,” he told his agent.. He planned a 40,000-word draft…

He and Ginny both worked on the background for this one, calculating orbits and transit times for his new Mayflower and for an effect he intended to use—all the Jovian satellites lining up—and calculating the load for the artificial greenhouse effect that would support the terraforming project. Ginny worked on the ecology and agronomics aspects, including a unique one-page instruction of how to turn sterile rock into fertile soil. Into this story Heinlein worked a favorite theme: the human rationale for frontier-seeking, its background a grand recapitulation of the settlement of the New World four hundred years earlier. Without an expanding frontier, Malthus’s depressing economic equations guaranteed resource wars. Serious realities—just the kind of thing his writer’s sense told Heinlein that boys hungered for. “Kids want tough books, chewy books—not pap.” Some of the material he had in mind was darker than usual. He asked Ginny’s opinion about killing off one of his characters. Remembering Little Women and the death of Beth, Ginny ruled it should probably pass. “After all, death is part of life.” Heinlein was able to finish the book under the working title Ganymede, in a month, on September 10, 1949. He set aside the cutting for later, since he now had other projects to get into shape. Bill Corson suggested a better title for this opus: “Farm in the Sky,” and that gave Heinlein his book title: Farmer in the Sky.

Robert A. Heinlein: In Dialogue with His Century, Volume 2: The Man Who Learned Better (1948-1988) by William H. Patterson Jr.