Project Hail Mary author says the movie improved on his book in one way

Andy Weir admits, ‘I wish that I had done it that way in the book.’

Book-to-screen adaptations often radically alter a book’s plot — sometimes so much that the original story is practically unrecognizable. Some authors are philosophical about those changes. Others get vocally mad about them. But Project Hail Mary and The Martian author Andy Weir has an unusual take. Weir tells Polygon that screenwriter Drew Goddard and directors Phil Lord and Christopher Miller improved the story in one specific way.

Project Hail Mary follows an astronaut, Ryland Grace (Ryan Gosling in the movie), on a lonely trip to the distant Tau Ceti system, where he’s hoping to find a solution to the parasitic infection that’s dimming Earth’s sun and causing worldwide calamity. Both the book and the movie open with Ryland waking up in space with amnesia. All the mission’s astronauts were placed in medically induced comas to preserve their sanity on the 13-year journey to Tau Ceti. Ryland’s memories gradually return, and both versions of the story fill in his backstory via flashbacks as he recovers information about himself and his goals.

In Weir’s novel, it emerges that Ryland tested positive for a rare gene that made him crucial to the space mission.

“In the book, there's a gene that makes you very resistant to long-term comas, and they could test for it, and only people who had that gene were candidates to be on the ship,” Weir says. “Ryland had that gene.”

Weir’s version has the mission going off the rails when an accident kills the lead and backup scientist assigned to the mission. Ryland is forced to take their place because none of the other available scientists have the “coma gene.” In the movie version, though, the accident kills the entire scientific team, and he’s the only remaining person knowledgeable enough about the current state of research on the solar infection to take the trip. As mission organizer Eva Stratt (Sandra Hüller) also brutally points out, he has no significant other, family, children, or other dependents to leave behind. If he leaves Earth on a one-way mission, no one else is going to suffer from his absence.

“Between Drew and the directors, they came up with a way to have Ryland be on the ship without having that coma gene,” Weir says. “Which is why he ended up being the last-minute replacement. Drew found a way to have that all happen, to have the [same] immediacy without having to resort to this little made-up side science that I had to come up with for the book. It always felt a little contrived to me in the book, and I'm glad that they found a way to do it without that in the movie.”

Most of the book made it to the screen just as Weir wrote it, apart from minor changes to streamline the story and focus on the space mission. (“I think if I made a list of my 10 favorite things in the book, I got nine of them on the screen,” Goddard tells Polygon.) Weir says one thing that helped him accept any tweaks to the characters, setting, design, and so forth was that he didn’t have strong visualizations of what any of those things should look like.

“In terms of what was in my mind versus what ended up being in the movie — I don't have a very visual imagination,” Weir says. “So when I'm writing, the characters are sort of blobs, the environment is sort of a different blob, and stuff like that. I guess I'm fortunate — other authors need to deal with the cognitive dissonance between what they imagine for their story, and then how it ends up being made into a movie. I never had anything firmly in my head for what things look like. Once I see them, they become canon retroactively.”

When the filmmakers consulted him throughout the production, showing him concept art and costume designs, he was always on board.

“Once I saw the Rocky puppet, I was like, ‘OK, that is now what Rocky has always looked like in my head,’” he says. “I see Ryan in costume as Ryland Grace, I'm like, ‘Oh, OK, that's what Ryland has always looked like, because there's no image to compete with.”

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Project Hail Mary is in theaters now.