Rocky Is Weirder Than You Think (ft. Andy Weir!)

TL;DR

Rocky from Project Hail Mary is scientifically grounded in a real exoplanet's conditions, with Andy Weir's 16-page notes detailing every biological and anatomical detail.

Key Points

• 1.Rocky's home planet is a real exoplanet called 40 Eridani Ab. It has 8.47 Earth masses, orbits closer to its star than Mercury does to our sun, and was discovered via the Dharma Planet Survey in 2018.
• 2.Arid's extreme conditions drive all of Rocky's biology. The planet has 29 atmospheres of ammonia pressure, 210°C surface temperature, a 5-hour day, and liquid water only because of that crushing pressure.
• 3.Aridians evolved from a deep-ocean-like ecosystem with no sunlight at ground level. Life photosynthesizes in the upper atmosphere, creating a food chain that bottoms out with apex predators like Aridians — the equivalent of ocean floor creatures.
• 4.Rocky's body is a radially symmetrical exoskeleton of literal rock with no eyes, five legs, and pentadextrous hands. No vision evolved because the surface is pitch dark; instead, they echolocate with their entire rocky carapace detecting sound vibrations in all directions simultaneously.
• 5.Rocky's brain is made of crystal and works via light interference rather than neurons. This gives Aridians near-eidetic memory and extreme math speed, but meant they never needed — and never invented — computers.
• 6.Aridians have two circulatory systems running mercury blood, functioning like a biological steam engine. The hot system (above water's boiling point) vaporizes water in muscle vesicles to create movement; dormancy (sleep) cools it so worker cells can repair micro-fissures.
• 7.Eating and excretion are the same act for Aridians, making communal dining taboo. Rocky opens a single body orifice to swap food, sanitizes it with heat, and considers this as private as humans consider using the bathroom — the cultural inversion is a key comedic moment in the book.
• 8.Aridians never discovered fire or electromagnetic radiation naturally, yet surpassed humans with Xenonite technology. Xenonite, made from xenon only stable in Arid's high-pressure environment, enables Rocky's spaceship, his xenonite bubble to survive inside Grace's ship, and even their space elevator.
• 9.Rocky in the film was almost entirely a practical puppet operated by five puppeteers called 'the Rocketeers.' Ryan Gosling could react to the physical puppet in real time and frequently improvised, with the crew digitally removing puppeteers and sticks in post-production.