Project Hail Mary's Best Deleted Scene Would've Fixed The 1 Thing The Movie Was Missing

Published Oct 14, 2026, 9:00 AM EDT

Once head of Screen Rant's Star Wars coverage and co-lead of Superheroes, Tom Bacon now works with the movies and books teams. He's a lifelong fan of the fantasy and sci-fi genres, and loves franchises such as Doctor Who and Marvel. You can find him on Twitter @TomABacon, on LinkedIn @tabacon, or on Muckrack under tombacon.

Tom has a wide range of interests, and he continues to serve his university as a volunteer chaplain. He's heavily involved with his local church, and anyone who checks him out on Twitter will swiftly learn he's into British politics too.

Project Hail Mary is easily one of the best science-based movies of recent years, and that's pretty much proven over on Rotten Tomatoes. Unusually, the critic and audience scores are both tied at a staggering 95%; that's with 430 critic reviews and over 25,000 verified ratings. The second film based on a novel by Andy Weir, Project Hail Mary follows on from The Martian as a sci-fi blockbuster hit. Despite that, though, the movie does have some flaws.

Weir is an impressive writer, not least because of the effortless way he blends science and plot. The Martian was much more science-heavy than Project Hail Mary, largely because directors Phil Lord and Christopher Miller were understandably much more interested in the relationship between Grace and Rocky. But, annoyingly, a single deleted scene from Project Hail Mary would have scratched the science itch a little bit more, and in so doing fixed a subtle plot hole.

Project Hail Mary's Deleted Scene Explained Why Tau Ceti Was Safe From The Astrophage

There are only five deleted scenes from Project Hail Mary, all available on the home release. Most of these are character moments, and it's easy to see why they were cut; they were played for humor, and would have disrupted the movie's dramatic flow. The exception is "We Could Be Cousins," a scene that drags on a little too long but actually serves an important purpose for both Grace and Rocky.

Grace is one of an ill-fated crew who travel to the planet Tau Ceti; this is the only star not being affected by an astrophage, a star-eating life-form that consumes solar energy and is effectively killing off the sun. By the end of Project Hail Mary, Grace and his alien friend Rocky discover Tau Ceti does indeed have an astrophage infection, but that the star survives because of an entire ecosystem on its fifth planet. Another life-form (a "Taumoeba") has evolved there, one that consumes the astrophage. But isn't that rather convenient?

"We Could Be Cousins" explains why the Taumoeba evolved on Tau Ceti-E (or "Adrian," as the pair name the planet). Grace realizes there's only one possible explanation for a stable ecosystem involving the astrophage and the Taumoeba; this must be where the astrophage evolved. The astrophage must have somehow been spread into space, perhaps from a coronal mass ejection, and it's an invasive species in every other star-system.

This deleted scene would have added a missing element of science back into Project Hail Mary, and it would have served an even more important purpose too; it neatly explains where the astrophage came from, why it has just become a threat now, and why Tau Ceti is the one star not affected by it.

"We Could Be Cousins" Lasts A Little Too Long

To be fair, I can still see why "We Could Be Cousins" was cut. The title gives it away; Grace and Rocky get diverted on the amusing idea that Tau Ceti is where all life began, a version of the panspermia theory. It leads to the gag that gives the deleted scene its title; Grace blows Rocky's mind by suggesting the two of them could be cosmic cousins. Lord and Miller are well known for their humor (Into the Spider-Verse remains one of the best superhero movies ever made, because of that balance of humor and drama), but this goes too far.

In this case, the joke unfortunately robs the science of its impact, which probably explains why Lord and Miller cut the scene. Personally, I can't help thinking it was a mistake; my preference would have been an edit, reducing the chatter afterward and allowing the revelation to linger a little longer. That would have made Project Hail Mary, an already near-perfect movie, even better — and fixed the science problem, too.

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