Resilience’s journey is one of self-discovery and understanding the human experience. From a practical standpoint, Sophie’s letters offer context as to how Resilience’s physical journey is viewed on Earth during his mission. As a motif, however, Sophie’s letters present the parallel journey of a preteen girl. The letters thereby, at once, powerfully humanize the rover while also emphasizing the intensity of coming of age, aligning that experience with the experience of going to Mars and back.

From her first letter, Sophie acknowledges that she is struggling with mixed feelings, especially toward Resilience and her mother. She is frustrated that the rover takes so much of her mother’s time and attention. However, much as Resilience learns to do with his new emotions, Sophie works through her complicated feelings with critical thinking: “Sometimes I get mad at you. But the real truth, which is hard to say, is that I’m kind of mad at Mom. Even though I’m proud of her, too” (39). Her letters often portray such examples of Balancing Emotion and Logic, often mirroring Resilience’s own progress within this theme. One of the most poignant instances comes as Sophie’s letters detail the return of her mother’s illness as Resilience grapples with the implications of Courage’s blankness.