Saving Rocky was only half the problem. Once Grace decided to accompany Rocky to 40 Eridani, he confronted his own biological clock. The Hail Mary lacked enough food to keep an adult human alive for the long deceleration burn and subsequent life on an alien planet. Eridian physiology is wildly incompatible with human digestive systems.
Eridians possess mercury-based circulatory fluids, dense carapaces, and thrive under 29 atmospheres of pressure in superheated ammonia environments reaching 210 degrees Celsius. Their food sources are completely toxic to human organs, containing heavy metals and alien amino acids that cause instant renal failure. To keep Grace alive during the voyage, Rocky devised a mechanical solution: recycling human waste, growing controlled cultures of edible non-toxic bacteria, and formulating a bland but nutritionally complete paste that barely kept Grace from starvation.
Upon arriving at Erid, the native engineers built Grace a massive residential dome. This habitat replicated Earth's 1-atmosphere sea-level pressure, filtered oxygen-nitrogen atmosphere, and manageable temperature bands. Eridian scientists used synthetic chemistry to produce uncontaminated water, carbohydrates, and cloned meat tailored to human biochemistry. Grace aged comfortably on an alien planet, never suffering biological rejection.
