This story contains major spoilers.
The film Project Hail Mary has just blasted past the milestone of $400 million revenue globally and is generating early Oscar buzz. And the film's depiction of interstellar travel and extraterrestrial life has reinvigorated the genre of science fiction and brought the wonder and "amaze! amaze!" of science into people's consciousness.
So how much of that science is really plausible?
In the film, middle school teacher Ryland Grace (Ryan Gosling) is recruited to help save Earth because of his history as a cell biologist with some iconoclastic ideas about life in the universe. During an emergency mission to a distant solar system, he must figure out how to stop a cosmic microbe from devouring Earth's sun.
In the wake of the simultaneous excitement over the ARTEMIS II mission, NPR went to NASA and other experts to find out about the real science behind many of the film's plot points.
The star that Ryland Grace (Gosling's character) is sent to, Tau Ceti, a real star about 11.9 light years away with possibly three planets orbiting it. Would it be possible for humans to travel to a place as far away as Tau Ceti?
It's not possible right now, says Lisa Carnell, division director for NASA'S Biological and Physical Sciences Division. "I don't think we are fully prepared to send humans to Mars, let alone light years away," she says. Given the leaps in technology that humanity has made in just the past century, however, she didn't want to rule it out. "In my mind, from what I know about how we've evolved in aviation and space exploration, yes, I believe it's possible [one day]."
How would NASA approach astronaut health on missions with extremely long travel times?
Carnell says there are many unknowns here, but some kind of medical solution would probably be necessary. "Even for the six-month transit to Mars, we've talked about how to keep [the astronauts] busy so that they don't have any psychological problems," she says. "I don't think that we are realistically looking at torpor [a medically induced coma or similar state of hibernation] as a possibility for Mars, but for some long, deep-space mission light years away, it would probably need to happen."
The challenge is that we don't have enough data on the safety and feasibility of torpor in humans, including how it would affect people's cognitive capabilities, she says. "There's so much we don't know and understand."
Doing the research is possible, but "that's many years down the road."
In the film, a robot tends to Grace during the four years he's in an induced coma in the spaceship. After waking, he appears to bounce back in hours — even climbing a ladder. What do we know about the safety and after-effects of being in an induced coma long term?
Doctors know a fair amount about the shorter term effects of comas. "On a much smaller scale, this is something we encounter in the ICU, where people are in a sort of medically induced coma with sedatives," says Dr. Shyoko Honiden, an associate professor of pulmonary, critical care, and sleep medicine at Yale School of Medicine. "Over days or weeks, we breathe for them, we support their heart and maintain their kidney function, we give them nutrition much like the robot does, and we try to move them around a bit."
But medically, such patients pay a price, she says. "Despite how advanced we've gotten in terms of our machines and medications, we are unable to fully replicate what the human body can do in this really fine-tuned, balanced way on its own."
You lose an estimated 2% of muscle mass per day during bed rest. This includes the diaphragm, she says, which is a muscle and "can become paper-thin at the end of a long illness on a ventilator. Some of our patients go through weeks of learning how to breathe again," she says.
Muscle wasting also affects the muscles of the digestive system, including those needed for swallowing, adds Dr. Rummana Aslam, an associate professor of orthopedics and rehab at Yale School of Medicine: "After four years, you would need rehab for a very long time to be able to speak, to swallow, and to move around."
Leaping off the bed and exploring the spaceship moments later as Grace does in the film, would be unrealistic, Aslam says.
There are also big issues with skin breakdown, also called pressure injuries, for anyone bedbound, she explains. And this can develop within 24 hours to a few days.
"Even if you turn the person every two hours [as currently recommended in critical care], the areas of your skin that are close to bone — the heels, the sit bones, the tailbone, the sacrum above it, and the back of your head — are very prone to skin breakdown."
Finally, says Honiden, it's unknown how the human brain would withstand such a lengthy coma. "We know from a medically induced coma in the ICU that brain dysfunction is pretty significant afterwards, and that neurocognitive dysfunction can be permanent. If you really shut everything down, can you slowly turn the switch back on? I guess that's the million-dollar question."
Grace encounters a spaceship from another planet and makes contact with the only creature aboard, who Grace calls "Rocky." Rocky's crewmates all died from radiation sickness because they were unaware of its risks. How does NASA manage these risks?
NASA's Carnell found it tough to believe that Rocky's civilization, the Eridians, would have technologically advanced to spaceflight without discovering radiation or its risks. Radiation is ubiquitous in space.
"Galactic cosmic radiation is pervasive — it's like you're swimming in a bath of radiation from supernovas all over the universe," she says. Though there are different types of radiation, all can cause radiation sickness. NASA is most concerned about radiation from solar particle events. "If you get hit with an intense solar storm, and if you don't have shielding or a therapeutic, you're going to die."
NASA uses satellites to track space weather, and "if there's going to be a big solar event, the astronauts go where there's more shielding that will absorb the radiation coming through," such as a part of the ship with a lot of stored water, which absorbs the radiation well.
The risks are greater when astronauts leave the magnetosphere, a giant invisible magnetic field surrounding the Earth that offers protection against radiation, as in the ARTEMIS II mission.
"So they are really going to be exposed to the full force of a solar storm. We've created a storm shelter inside the Orion spacecraft, and they were testing that out. You open it up and climb down inside, and you're surrounded by all this extra material that helps ameliorate the effect of the radiation coming through."
To save Earth's and Rocky's suns, Grace and Rocky have to breed an extraterrestrial microbe predator called taumoeba to be resistant to the nitrogen concentration on Venus. Is it possible to selectively breed bacteria in a short time span?
Nathan Crook, an associate professor of engineering at North Carolina State University, has worked on breeding microbes to eat plastic in the ocean while withstanding marine pH levels. Every microbe is a little different when it comes to trying to breed it to have certain characteristics, so it's hard to say how realistic this part of the film is, he says. But it's not entirely implausible either, and some principles are true for nearly any microbe.
"Let's say we want to do this evolution for pH tolerance, such as a probiotic that can survive acid in the stomach better. Those types of experiments will likely go on for a week or two, and it will improve a bit, and then it'll plateau," Crook says. "Then, after some time in the plateau stage, something will happen, and it'll get a little bit better accidentally, but that's something you can't really predict."
How quickly Rocky and Grace could breed the type of taumoeba they need will depend on what genes it already has and why it's not resistant to the nitrogen already. "Nobody really understands how tolerance works," Crook says.
It also depends on whether only one gene or multiple genes would be involved in making it tolerant. If the microbe simply needs to break the nitrogen down into something non-toxic, "that could be a single gene and you could do it really fast, but the microbe would have already needed to have a gene in its genome that does something similar to what it's being evolved to do," he explains. "You can't evolve something from nothing," he says.
In the story, the taumoeba evolves an additional adaptation that complicates Rocky and Grace's mission. Accidentally evolving a microbe with inconvenient other adaptations is realistically possible too.
Grace's spaceship can be spun like a centrifuge to create artificial gravity so that scientific instruments will work properly. Has NASA considered using ship centrifuges to create artificial gravity?
Artificial gravity isn't necessary to use lab equipment in space, Carnell says. Astronauts have been doing lab work on the space station in microgravity — a state where gravity is extremely weak — for 20 years. "It's amazing how much we've accomplished. We have figured out how to do [gene] sequencing, microscopy, combustion experiments, and biomanufacturing," she says. "We've demonstrated you can live and work in microgravity."
But there is one reason to consider adding a centrifuge to part of a spacecraft to create a space with artificial gravity. "If we wanted to add a centrifuge, it would be more for human health for long-duration missions, specifically for bone and muscle," Carnell says.
Artificial gravity might benefit cardiovascular health too, she says, but the biggest reason is to slow the muscle loss that astronauts experience in space. NASA has even explored some designs for adding a centrifuge-like component to a spacecraft, she adds.
When Grace and Rocky meet, they must establish communication. The two reach a level of fluency that allows them to solve their problems together. How realistic was the portrayal of communication between a human and a creature with nonhuman speech?
The hypothetical study of how humans and extraterrestrials might communicate is a real scientific field, called xenolinguistics, that includes researchers from linguistics, animal communication, and anthropology. Martin Hilpert, a professor of linguistics at the University of Neuchâtel in Switzerland, says the film "gets a lot of things right" for how such an encounter might occur, though it also employs a lot of "happy coincidences" too.
"For example, Rocky can understand iconicity, where you have a little figurine that represents a person, and that is not a trivial thing to understand," Hilpert says. "Primates can't really do iconicity that well, but they understand pointing," something else Rocky understands that isn't necessarily a given.
A shared understanding of iconicity and pointing makes the next step easier: understanding that the basic sounds of human languages represent things and ideas.
But there's still a big assumption here — that "these two completely different civilizations would have common nouns," says Irene Pepperberg, the scientist at Boston University who worked with the African grey parrot Alex, one of the smartest birds ever studied.
She also points out that animals see different wavelengths and hear at different frequencies than humans, and the same might be true of an alien species.
"It was very clever making Rocky blind because a lot of things in animal communication are not just vocal communication but visual," she says. But deciphering Rocky's tones as easily as Grace and his computer do would be more believable, she says, if scientists had already decoded whale song, for example, but biologists have not yet done that.
The fact that Grace and Rocky start their word list with numbers makes sense, says Arik Kershenbaum, an associate professor at the University of Cambridge who has studied wolf calls. "The real issue is, how do you convey interesting information?" Having a scientist talk to an engineer also facilitates communication. "These are two individuals with a shared goal who are thinking carefully about how to achieve that goal."
Achieving meaningful dialogue will still take a long time, says Jeff Punske, an associate professor of linguistics at Southern Illinois University in Carbondale. "The timeline for successful communication was way too fast," he says. "All that said, I did appreciate that there was any effort to show the development of communication."
Tara Haelle is a Dallas-based science journalist.
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