At a staff meeting, Stratt introduces climatologist Dr. François Leclerc to cut through conflicting forecasts. Pressed for numbers, Leclerc predicts that within nineteen years half of humanity will die due to climate-driven crop failures. Stratt rejects fatalism, orders an engineered greenhouse solution, and assigns Leclerc to devise it despite his ethical qualms.

In the present, Grace teaches Rocky about radiation and its biological effects, revealing why Eridians never discovered it: Erid’s immense magnetic field and thick atmosphere block radiation completely. Rocky’s survival is traced to his workshop location, surrounded by Astrophage fuel that blocked radiation; they agree to add Astrophage shielding. They also reason both species sit in a narrow technological band and discuss panspermia as a plausible shared origin.

Back on Earth, the team stages a clandestine naval operation off western Antarctica. With global exclusion in place, Leclerc oversees the detonation of 241 buried fusion devices to calve the ice shelf, warm the atmosphere via methane release, and buy time. The blasts are remote and invisible from the carrier; Stratt reassures a distraught Leclerc as he grapples with the moral weight.

Grace and Rocky exchange deep biological insights. Eridians are “steam-powered,” with dual circulatory systems, largely inorganic structures, and a radiator-based heat dump; sleep is total paralysis during maintenance. Rocky marvels at human vision while Grace marvels at Eridian sensory processing and physiology.

Rocky completes a xenonite geodesic sphere and an Astrophage-based cooling life-support unit, enabling him to survive aboard Hail Mary. He begins rebuilding the divider with a larger airlock to bring the sphere through. Grace secures the tunnel, tidies the control room, and prepares to host his first onboard visit.