The much-anticipated sci-fi film Project Hail Mary is out in theaters today. In it, light-eating alien microbes sap the sun’s energy, threatening life on Earth with extinction. To find a solution, an unlikely hero—a middle school teacher played by Ryan Gosling—is sent on a one-way mission to the star Tau Ceti and encounters an otherworldly sidekick nicknamed Rocky along the way.
The premise is fantastical, but the concepts that inspired the story are real—and not as implausible as you might think.
Andy Weir, author of the eponymous book that inspired the movie, carefully researched the physics, astronomy and biology that drives the plot, and he even consulted on set to preserve scientific accuracy while actors ad-libbed during scenes.
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“Actors are very much part of the creative process, [but] sometimes the science on what they say would be wrong,” Weir says. “And so I’d go over to the directors, and then they’d say, ‘Oh, okay, well, let’s try that again, but this time say nanograms instead of milligrams.’”
In that spirit, Scientific American spoke with Weir, as well as an astrobiologist, a physicist and a couple of astronauts about the real-life science that inspired this work of cinematic fiction.
How do the film’s “Astrophage” work?
The film’s premise is that alien microbes called Astrophage (roughly translated from ancient Greek as “star eater”) colonize the sun and travel between our star and Venus to breed. As the population of star-hugging Astrophage grows, it dims the sun’s light, jeopardizing life on Earth.
Microbes could make a sun-Venus round trip with the right amount of power, but the journey would demand different amounts of it in each direction, says Chad Orzel, a physicist at Union College. “From the sun to Venus wouldn’t be that hard because there’s already a steady flux of [solar] particles going in that direction,” he says. The return trip “would require a bit more effort” to counteract solar wind, however.
Weir’s way of dealing with this problem, he says, was to imagine Astrophage as able to absorb neutrinos, so-called ghost particles that don’t tend to interact with other matter. A neutrino can slip untouched right through a light-year’s worth of lead, for instance, and every second tens of billions of them pass through every cubic centimeter of Earth—and through you, dear reader. Most of these neutrinos come from the sun, which is constantly spewing them out as it shines. But these ghost particles do carry mass (and thus energy via Albert Einstein’s handy equation E = mc2). If Astrophage could use the sun’s energy to create neutrinos within their cell membranes (the “science” gets very hand-wavy here), Weir mused, perhaps they could use the particles as propellant. Astrophage could convert most of the neutrinos’ mass back into energy (or, really, infrared light) that they would then directionally beam out to produce thrust.
Ryan Gosling as Dr. Ryland Grace in Project Hail Mary.
Jonathan Olley © 2026 Amazon Content Services LLC. All Rights Reserved.
This (imaginary) process would be efficient and powerful. In the film, Astrophage make up the fuel that powers the Hail Mary, the ship that takes Gosling’s character to Tau Ceti.
“The idea is out there,” Orzel says. “If you want to completely convert matter into energy, the way you usually go about that is by combining it with an equal amount of antimatter. [But] there just isn’t that much antimatter running around.”
Are Tau Ceti, 40 Eridani and the planet Adrian real places in the universe?
Yes, these places really exist, though Adrian is a fictional name. Tau Ceti is a star about 12 light-years away from Earth, and 40 Eridani, the Astrophage-plagued star system that Rocky is from, is about 16 light-years away from Earth. Adrian, the Tau Ceti world that the characters visit, really exists in astronomers’ exoplanet catalogs as Tau Ceti e (although we know very little about it).
In the grand scheme of things, these places are not all that far apart. Using nearby stars that are similar to ours in the story, Weir says, was an intentional choice.
In the Project Hail Mary universe, all life in our solar system’s sector of the Milky Way comes from an ancient ancestor of Astrophage that long ago radiated out from Tau Ceti, Weir says. “Since all the life in the story is distantly related,” he says, “I wanted it to all be around similar stars because similar stars end up with similar elements available on the planets.”
Author Andy Weir on the set of Project Hail Mary.
Jonathan Olley © 2026 Amazon Content Services LLC. All Rights Reserved.
Just like much of life on Earth, Astrophage have cell organelles called mitochondria, which would be in line with the idea that terrestrial life and Astrophage share a common ancestor, notes astrobiologist Mike Wong of Carnegie Science. We know that mitochondria evolved on Earth, however, he adds.
“There’s plenty of life on Earth that doesn’t have any mitochondria, like the bacteria and archaea,” he says. “If there was an origin for life in the greater cosmic neighborhood, it would seem that Earth would have to be the origin.”
Artificial gravity is a big part of this film. How close are we to making that happen?
Artificial gravity can exist in theory and could work much like it does on the Hail Mary. Part of a spacecraft could rotate in a circle, and the resulting centripetal force could simulate gravity for the passengers within.
Drew Feustel, lead astronaut at the private space station company Vast and one of the film’s technical consultants, says that building a spinning habitat is not only possible but also on Vast’s list of upcoming priorities. But he points out that there’s no known way to simulate gravity while on land (which does happen at one point in the film).
Gosling’s character, a middle school teacher, trains to be an astronaut in a short period of time. How realistic is that?
NASA, or any other public space agency, isn’t in the business of throwing just anyone into space. But there has historically been a sliding scale of qualifying expertise, says former NASA astronaut Mike Massimino.
Between 1983 and 2003, NASA trained “payload specialists” to fly as space shuttle crewmembers with niche, mission-critical knowledge. And, famously, a teacher really was selected to go to space. But overall, payload specialists received less training than full-time astronauts. “It was a huge difference, of course, in what you could do,” Massimino says.
A quick glance at NASA’s past and present astronaut corps shows that its members have very diverse backgrounds, from teaching to engineering to piloting to planetary science. What an astronaut needs to know depends on the mission and skills the other crewmembers possess, Massimino says.
At minimum, “what you need to be able to do is make a meal and use a toilet and know all the emergency procedures.”
When Gosling’s character is stranded in space without his crew, the gaps in his knowledge become apparent. But the film does a remarkably realistic job of showing how even the basics can be hard to nail at first and perhaps even pokes fun at romanticized films about space.
“It’s very unglamorous,” Feustel says of space travel. “That’s the reality of it.”
