This story contains major spoilers.
The film Project Hail Mary has grossed hundreds of millions and renewed public interest in science fiction. It follows Ryland Grace (Ryan Gosling), a former cell biologist turned middle school teacher, who is sent on an emergency interstellar mission to stop a microbe that is draining the Sun’s energy. NPR asked NASA and other experts how much of the movie’s science is plausible.
Can humans travel to Tau Ceti?
Tau Ceti, the star Grace is sent to, is real and about 11.9 light years away with possible planets. Right now such travel is impossible. Lisa Carnell, division director in NASA’s Biological and Physical Sciences Division, says humanity isn’t ready even for routine crewed Mars missions, let alone voyages measured in light years. Still, given past leaps in aviation and space exploration, she won’t rule out far-future possibilities.
Torpor (long-term induced hibernation) for deep-space travel
For extreme, multi–light-year trips, Carnell says some sort of medical state like torpor might be required. We lack sufficient data on the safety and cognitive effects of long-term torpor in humans. Research is possible but would require many years.
Long induced coma effects
The movie shows Grace in an induced coma for years and recovering quickly. Clinicians note this is unrealistic. Dr. Shyoko Honiden (Yale) points out that while ICU teams support sedated patients for days or weeks, machines and meds cannot fully replicate normal physiological balance. Prolonged bed rest causes severe muscle wasting—roughly 2% of skeletal muscle mass lost per day early in critical illness—including the diaphragm, which can thin to the point patients need extended respiratory rehab. Dr. Rummana Aslam (Yale) highlights loss of swallowing and digestive muscle function and the long rehabilitation required after years of immobility. Pressure injuries (skin breakdown) can arise within days if patients are bedbound. Neurocognitive dysfunction after long medically induced comas is common and may be permanent; whether the brain could be “restarted” after years is unknown.
Radiation and an alien civilization’s awareness
In the film, Rocky’s (the alien) people died from radiation because they didn’t understand it. NASA experts find that unlikely: galactic cosmic radiation and solar particle events are pervasive in space, and any civilization developing spaceflight would likely encounter radiation effects. NASA tracks space weather with satellites and mitigates risk on missions (for example, ARTEMIS II) by moving crew to better-shielded parts of a vehicle or into purpose-built storm shelters using materials like water for shielding. Leaving Earth’s magnetosphere exposes astronauts to much higher radiation risk.
Breeding extraterrestrial microbes
Grace and Rocky selectively breed a microbe (taumoeba) to tolerate a high-nitrogen environment. Nathan Crook (North Carolina State University), who has worked on evolving microbes for specific tolerances, says directed evolution can change traits on short timescales in some cases, but outcomes depend on what genes are already present. Experiments to improve tolerance (e.g., pH resilience) can show measurable change in weeks, often plateauing and sometimes improving unpredictably later. If tolerance requires only a single, already-present gene variant, change can be rapid; if multiple complex changes are needed, it may take far longer. Accidental evolution of other, problematic traits is also realistic.
Artificial gravity via centrifuges
The ship in the film can be spun to create gravity for lab work. NASA notes artificial gravity isn’t necessary for running many laboratory instruments—microgravity research (including gene sequencing, microscopy, combustion, and biomanufacturing) has been done on the ISS for decades. The main reason to add centrifuges would be for human health on long missions: to counteract bone and muscle loss and possibly protect cardiovascular function. NASA has studied centrifuge-like designs for spacecraft interiors as a countermeasure to microgravity’s physiological effects.
Human–alien communication
The film depicts rapid development of meaningful communication between Grace and Rocky. Xenolinguistics is a real interdisciplinary field (linguistics, animal communication, anthropology) that studies how contact might proceed. Martin Hilpert (University of Neuchâtel) says the movie gets many things right—using iconic objects, pointing, and building a symbol list are valid strategies—and that starting with numbers is a sensible approach. But the film relies on lucky coincidences: not all species grasp iconicity, and sensory differences (e.g., hearing ranges, visual wavelengths) complicate mapping signals to meaning. Irene Pepperberg (Boston University), who worked on the African grey parrot Alex, notes many nonhuman communication cues are multimodal and that decoding alien tones as quickly as the film shows would be more believable if comparable decoding problems (like fully understanding whale song) had already been solved. Jeff Punske (Southern Illinois University) says the realistic timeline for robust communication would be much longer than portrayed, though he appreciated the film’s effort to show the process.
Bottom line
Project Hail Mary blends plausible scientific ideas (space radiation risks and mitigation, constraints on long-term coma, directed evolution principles, and xenolinguistic approaches) with dramatic shortcuts (rapid recovery from years of coma, very fast microbial evolution in unknown organisms, and an accelerated timeline for establishing complex cross-species communication). Many of the film’s central scientific themes are grounded in real research, but several key elements would be far more difficult, slower, or riskier in reality.
Tara Haelle is a Dallas-based science journalist.