Grace and Rocky display impressive scientific competence even under duress. Though his entire time aboard the Hail Mary is a series of life-threatening dilemmas, Grace manages to overcome his fear and perform complicated calculations. His competence is only threatened by sleep exhaustion and the influence of painkillers, but even in the face of these obstacles, Grace maintains a degree of scientific prowess. Often, the tension between life-threatening stress and the need for accuracy is highlighted through humor, and Grace frequently jokes that his knowledge is all due to his role as a junior high school teacher rather than his background in academic science.

Like Grace, Rocky keeps a cool head under pressure, sometimes thinking even more calmly than Grace himself. Weir presents Eridians as pragmatic by nature, grounding Rocky’s extraordinary capabilities in matter-of-fact cultural norms, as opposed to Grace’s impressive functioning under stress by human standards. Weir suggests that competence, in combination with ingenuity, ensures survival even when one is facing the greatest of odds.

The effects of Astrophage are a kind of climate change, resulting in global cooling rather than global warming. Throughout the novel, Weir uses the real effects of climate change as a reference point for the disasters that would be caused by solar dimming.