SPOILER WARNING: The following article contains major spoilers for Project Hail Mary. If you have not yet seen the film, proceed at your own risk – or perhaps instead opt to read CinemaBlend's spoiler-free Project Hail Mary review.
When it comes to the changes made adapting Project Hail Mary for the big screen, I understand the vast majority of them. There is simply too much material in the book for it all to be realized on screen, and that means that screenwriter Drew Goddard and directors Phil Lord and Chris Miller had to make some notable cuts. But while I get simplifying the docking procedure for the Hail Mary and the Blip A and eliminating the sequence where Antarctica is purposefully bombed to slow the cooling of the planet, there is one major alteration that I was not only surprised to see, but I think is a detriment to the telling of the story: the third act crisis with Grace's food supply.
For those who either haven't read the Andy Weir-authored novel or simply need a refresher because it's been a minute since you did, let's start with a quick rewind…
Grace's Food Supply Is A Major Problem In The Final Chapters Of Project Hail Mary
As is repeatedly noted in both the book and film versions of Project Hail Mary, Grace's trip to Tau Ceti is designed to be a suicide mission, and that has an impact on the ship's inventory. The movie addresses this with a conversation between the protagonist and Rocky about Hail Mary's Astrophage fuel supply (the alien is able to solve the problem because of extra Astrophage available aboard the Blip A), but there is no mention in the adaptation about how much food he has available, and that's a huge deal in the source material.
Because both Yao and Ilyukhina die during the trip, Grace has three times the amount of solid food he would otherwise have when he arrives at the Hail Mary's destination – but even with all of that extra nourishment, there isn't enough to last the long journey back to Earth. He also can't eat Rocky's food from Erid, as it is filled with toxins that would kill him. The only solution he has for nutrition is what he refers to as "coma slurry," which was supplied to him when he was unconscious during the initial journey and has a taste he compares to aspirin.
Not wanting to risk going back into a coma, Grace opts for trying to live off the slurry on his way back home after he and Rocky part ways… but then the Taumoeba leak happens. Both the book and the movie depict this crisis: the protagonist is forced to choose between returning home or simply sending his findings back to Earth while he goes to find and save his friend. The end result is the same in both versions, but because the film never features any kind of discussion about Grace's food supply, the stakes are very different and the character's atonement for past sins isn't as powerful on screen as it is on the page.
In The Book, Grace's Trip To Save Rocky Is A Chosen Suicide Mission With Proper Redemption For The Apprehensive Astronaut
At the end of the second act in Project Hail Mary, a recalled memory changes everything that we know about the character. While Grace spends most of his mission under the impression that he sacrificed his life to try and save Earth (the ultimate hero move), the reality is that he was a coward who had to be drugged and dragged on to the ship after the scientist lined up to be on the crew and his backup were killed during an accident. By the time he figures out the truth, he is too invested in the work to do any kind of protest.
This, of course, is vitally important to keep in mind when it comes to the choice he makes between going to Earth and saving Rocky – but the fact that the food issue isn't brought up in the movie makes the decision far different from the book. In the adaptation, Grace is depicted merely giving up his chances of seeing his home planet again; in the source material, he comes to terms with dying so that he can save Earth, Erid, and his best friend, as even the coma slurry supply is going to eventually run out.
But it's not a sad ending. When Grace re-finds Rocky and explains that he has no chance of survival, his friend again gives him a lifeline: while he will soon run out of human food and can't eat Eridian food, one thing on his ship with nutritional value that he can eat is Taumoeba. It doesn't prove to be the healthiest meal plan, and it results in him being a bit sickly for a time, but it keeps him alive until he gets to Erid, and when he gets there, scientists are eventually able to provide him with a proper protein-rich diet of what he calls "Me Burgers": burgers with meat synthesized from his own flesh.
Is the novel's ending a touch grosser than the movie's? Most definitely. But I also think it is much more effective in executing a redemption for Grace because of the simplicity of the one-to-one comparison: in two instances he is presented with the moral choice to sacrifice himself for the greater good, and while he fails in the first instance, he makes proper amends in the second.
To be sure, adding this material from the book to the movie would have made it longer, and at 156 minutes, Project Hail Mary is pretty damn long as it is. With that being said, I definitely find this particular cut in the adaptation process to be surprising and to the detriment of the movie, and should we someday see an extended cut come together (which we saw happen with Ridley Scott's adaptation of Andy Weir's The Martian), I'd be hopeful to see that stuff put back in.
