About
Last updated: October 25, 2026
Hail Mary Science is a free, bilingual guide to the real science in Project Hail Mary, Andy Weir's novel. This page explains who makes it, why it exists and how each page is put together.
Who's behind it
I'm Daniel Ruiz, the author and owner of this site. I'm a reader of Project Hail Mary and I've really enjoyed all of Andy Weir's books. I wanted to build something that explained every detail of the book and its universe in an interactive, visual way, and this guide is the result.
It's a personal project: there's no company or editorial team, just a reader who finished the novel wanting to properly understand what the narrator works out in every chapter.
Why this site exists
Project Hail Mary does something unusual for science fiction: nearly everything that happens can be checked. Ryland Grace measures gravity with a pendulum, works out the makeup of an atmosphere from a spectrum and solves fuel problems with the rocket equation. The book drops the hints but rarely stops to explain them, and plenty of readers (me included) were left wondering whether the numbers actually add up.
This site tries to answer that. Each chapter of the guide takes the science from one stretch of the book and unpacks it: which law of physics is involved, where the figures come from, how the calculation works, and how far real science goes before the author's imagination takes over.
It's written for people who never studied science. If you can add and multiply, you can follow every explanation, and every formula comes with a worked example.
How the content is made
Every page follows the same approach:
- I summarize, in my own words, the situation in the book that raises the problem. No passages from the novel are reproduced.
- I explain the science from the ground up, with a numerical example.
- I separate established science from creative license. Astrophage, xenonite and the Eridians are invented; relativity, spectroscopy and the Tsiolkovsky equation are not.
- Where there's a simulator, I explain what each control does and what's worth trying.
Spoilers
The guide follows the order of the book, so each chapter assumes you've read up to that point. If you haven't finished the novel yet, move through the guide at the same pace as your reading. The glossary is written so it can be used at any time.
A fan project, not affiliated
Hail Mary Science is an independent fan project. It is not affiliated with, sponsored or endorsed by Andy Weir, the novel's publishers, Amazon MGM Studios or any other company involved in the film adaptation. The names of the work and its characters belong to their respective owners and are used only for commentary and educational purposes.
How it's funded
The site is free and needs no account. To cover the domain, hosting and the time it takes, it may show Google AdSense ads and includes Amazon affiliate links to buy the book. Neither advertisers nor Amazon have any say over the content.