Review: Project Hail Mary
“Human beings have a remarkable ability to accept the abnormal and make it normal.”
Project Hail Mary
Andy Weir
485 pages - 2021 - fiction, sci-fi
February 9th, 2026 — February 18th, 2026
Rating: ⭐⭐⭐⭐⭐
Lately I’ve been surrounded by a ton of media about the Sun dying.
It was completely by coincidence—I played the video game “Outer Wilds” over the holidays at the insistence of my brother, and I do not think I have stopped thinking about it since. I’ve listened to podcast episodes released in the past few weeks about heliology, quantum mechanics and astrophysics, the heat death of the universe, supernovae, the big bang; I’ve heard people around me talking about the Sun finally exploding billions of years in our future.
Also by coincidence, my birthday was at the beginning of this month, and I asked my brother to get me this book for it. He had lent me his library copy of it about 5 years ago, while we were on summer vacation with our family, and I had about 3 days to read it before we had to go back to our respective regular lives. I tore through it, and loved it, but I had forgotten most of the details and a good amount of the plot after all this time. I knew that I loved it, and I knew that I wanted to reread it before the movie comes out (March 20th!).
Rereading it this time, it felt newly profound. The story is about a man who is on a “hail Mary” mission to save Earth after they realize that the Sun is being consumed by a mysterious black matter. Naturally, this is a terrifying concept, and one that is full of depressing notions that the main character actively tries not to think about. It isn’t called “Project Hail Mary” for nothing—he is not supposed to survive, and he knows it.
If you have not yet played “Outer Wilds” and love this book, or if you have played it and haven’t yet read Project Hail Mary, the two feel like love letters to one another and to being alive. Both are about the futility of time and the inevitability that the world will, one day, disappear. They both also offer lessons over and over again about recognizing the beauty of the world around you while it’s there.
After all, there’s nothing like facing the end of humanity and all life/existence as we know it to make you grateful for what you’ve got in the here and now.
Summary (Spoilers!)
A man wakes up in a mysterious place, hooked up to a bunch of tubes and wires. He realizes over time that he has no memories, but they come back in flashes. He learns that his name is Dr. Ryland Grace, and he was formerly an astrophysicist who became a middle school science teacher but was recruited to be a part of a special mission.
His memories show him that sometime in the past, a scientist found out that the Earth’s brightness was about 0.01% lower than it should be. They found some black dots near the Sun and Venus, which emitted a specific band of infrared radiation that they named the Petrova frequency. Scientists around the world started working on learning more about these things, and ended up recovering some for study back on Earth. They realized that at the current rate of consumption, their Sun would decrease by enough power to cause a mass extinction event in about 30 years. Ryland Grace was found by Eve Stratt, the head of the European Space Agency, and recruited to help them study the odd dots.
Grace learns that he had two crewmates on the ship, but they both died, and quite possibly long ago as their bodies have desiccated. He had been placed in a coma for the long journey and was the only one to survive. He explores the ship and learns that it’s called the Hail Mary. He also learns that the star near which his ship is located is not the same sun; he’s no longer in the solar system.
We learn that Grace had written papers debating the theory that all life needs water to survive. This is why they had recruited him—they thought that the dots could be living, since they can move, and they also thought they might not be made of the same materials, since they live so close to the Sun and Venus. Grace tries to study them and finds it nearly impossible until he punctures one with a miniscule needle, causing the dot to turn clear and the organism to die. Inside, he finds a cell with the typical organelles and materials seen in Earth organisms, including water.
Grace wanted to keep studying the creatures, which he deemed Astrophage (for “star-eating”), after Stratt said they were determined safe enough to send around the world for others to study. He convinced her to let him keep three Astrophage for his study and was able to determine that they are attracted to light from the Sun for gathering energy and carbon dioxide from Venus for multiplying when he realizes that his three Astrophage have become four.
Upon hearing this news, Stratt assembled a team to study Astrophage breeding, including Grace, on a Chinese aircraft carrier far out in the ocean. She explained to Grace that they want to breed Astrophage because they’ve discovered that they are extremely efficient at converting energy to mass and vice versa, so they can be used as rocket fuel. They want to breed millions of Astrophage as well as a ship to get the crew, three people, to Tau Ceti.
Tau Ceti is the only nearby star that they’ve found that is not getting significantly dimmer. They want to determine why—is it immune to Astrophage? She mentions that, even with the Astrophage fuel, it’s 12 light-years away, meaning the crew will either spend at least six years in extremely close quarters, possibly leading to fighting, or they will be in comas for that long, which often causes death. She’s found that there are about a million people in the world with a gene that makes them more resilient to comas, leading to less mortality and higher rates of brain functioning when they come out of it. They’ll have to find the most qualified of those million people to go on the mission to save their planet.
Grace’s ship makes it to Tau Ceti’s solar system, and he is able to determine that there is a Petrova wavelength, meaning there are Astrophage there, too, just not dimming the star. He’s excited to recover some and start studying them when he sees something moving towards him and realizes that it’s another ship, one of alien design. They communicate with some ship movements, so Grace notes that there’s a living intelligent being inside. The alien ship sends a cylinder to the Hail Mary, and Grace goes on an EVA to retrieve it, bringing it back inside and learning two things: it’s burning hot, and it smells of ammonia.
When he opens it, he finds a map of stars, with notation he’s able to determine means that they came from the 40 Eridani system to Tau Ceti because of the Petrova lines. Grace adds some marks to Sol on the model and sends the cylinder back; when he receives another one, it’s a model of the Hail Mary and the alien ship, connected at their respective portals to space, an invitation for them to meet one another. The aliens get to work and connect a tunnel between the ships, with a wall in the middle, so they can determine compatibility. Grace notes that his half of the tunnel has an airtight seal and is accessible. While he’s checking it out, he hears three knocks on the wall.
One section of the wall is clear, so Grace and the alien are able to look at one another—the alien, which Grace dubs “Rocky”, looks like a spider made of rock, with 5 articulated limbs, 3 fingers each, and what appears to be clothing. While Grace is in his ship, Rocky leaves another cylinder in his side of the airlock, which contains models of what Grace determines are molecules. For Grace’s one atmosphere of pressure and primarily oxygen, Rocky has 29 atmospheres and breathes primarily ammonium, meaning their atmospheres are deadly to one another. But they are able to communicate how they display time, and Grace determines one Earth second is about 2.3 Eridian seconds, and learns they count in base 6.
Grace realizes through some communication and passing objects back and forth that Eridians cannot see, but instead use sound to map out what is around them. He learns that they make chords as words and starts to map them on his computer, creating a script that automatically translates what Rocky says. He finds that Eridians, or at least Rocky, have an incredible memory, so the alien does not need a translator. Rocky also asks to observe while Grace sleeps, and then asks Grace to observe him sleeping. Before Rocky sleeps for the first time (that Grace knows of), he says that there had been 23 crew members, but they all died, just like Grace’s crew. They did not know about the radiation in space, and all of them but Rocky died. Their star was also being destroyed by Astrophage, and they headed to Tau Ceti to figure it out just like Grace did.
There are flashbacks showing Grace learning more about the process leading up to Project Hail Mary, including a visit to an Australian prison where an inmate had an idea for blackpanels set up in the Sahara Desert to greatly scale the production of Astrophage. Grace had also learned that Astrophage stored energy by creating neutrinos, the process of which emitted the Petrova wavelength and required the exact temperature at which they found that they held. To combat the global cooling, Stratt convinces governments to use nuclear bombs on Antarctica to release methane stored in the ice, which causes the greenhouse gas to build up in the atmosphere for about 10 years and would decrease the rate of cooling.
Grace explains to Rocky what radiation is, and says that he was the only one to not die because he was mostly in the engine room, which was surrounded by Astrophage, which completely shield from radiation. The Eridian planet also has a much stronger magnetic field, as well as a thicker atmosphere and no solar radiation, so they never encountered radiation before their space travel. They also discuss their biology and Grace learns that Eridians are mostly inorganic matter. Rocky makes a life support system for himself and then asks if he can come see Grace’s ship. When he gets there, he asks if he can move his stuff into Grace’s ship so they can turn on the gravity and do some science together to try to figure out how to solve the Astrophage problem. Rocky moves in, bringing tons of stuff with him. Grace learns that Rocky is about 291 years old, with an average lifespan of 689 years; he’s been in the Tau Ceti star system for about 46 years.
Grace met the scientist, Dr. Lamai, who had done the experiments to determine coma tolerance in people. He is uncomfortable with the animal testing happening, but she is trying to engineer machines to keep people in comas alive among any number of issues that arise. While they’re there, Stratt has her blood taken and tested for the coma-tolerant genes, and insists that Grace does the same to “set an example” for the other scientists. The more people that they’re able to test, the wider the pool for volunteers will be. Grace meets the crew and backup crew of the mission, including his present-day and deceased crewmates. He learns that he has the genetic markers for coma tolerance from DuBois, the American man and science specialist meant to go on the mission.
On the Hail Mary, Rocky has gotten to work making some areas for him to inhabit, and Grace has them on a course towards Tau Ceti e, the planet with the most prominent Petrova line in the system. Rocky names it after his mate from Erid, and Grace gives it the English name “Adrian”. Rocky also says he’s going to eat, and that it is a private affair for Eridians; Grace insists on watching, and concedes that it is quite a gross process.
Grace and Rocky are able to collect some Astrophage from the atmosphere around Adrian. Grace examines them with a microscope and finds tons of Astrophage, as well as a bunch of other microscopic life. He and Rocky conclude that this is where Astrophage is from, the abundance of methane in the atmosphere of Adrian is from life, and that there has to be a predator of Astrophage present on Adrian, since there are less Astrophage present than expected.
They find no predators, and come up with a crazy idea to go “fishing” 10 kilometers below the ship to try to find predators in the Astrophage breeding areas. Rocky also says he can provide Grace with the fuel he needs to return to Earth when their project is done, and Grace realizes that Eridians did not know about time dilation, so they have much more Astrophage fuel than they needed. They try their fishing plan, and it works for a little while, until the hull starts to melt from the radiation from the Astrophage interacting with the atmosphere; Grace nearly passes out from the gravitational forces, has to jettison some of the fuel containers, and when he wakes up, he smells ammonia and realizes that Rocky had left his life support bubble to save him. Rocky is curled up and unconscious. Grace is able to minimize the gravitational forces, so he quickly engineers some protection for Rocky, including a robot to blast air in Rocky’s vents to clear some of the soot that possibly happened from his blood being quickly oxidized.
Rocky wakes up, weak but alive, and both of them take stock of their wounds. Over time, they slowly regain function of their facilities and are able to get almost back to full health and speed. Grace, with Rocky’s help, collects the samples from their nearly catastrophic mission and looks at them under a microscope. He finds a predator of Astrophage, which he names Taumoeba, and they start breeding them as well.
In a flashback, Grace asks the three astronauts their preferred method of death should they reach a point where there is nothing else to do. DuBois says he wants to die by nitrogen asphyxiation, either in his EVA suit or the airlock. Ilyukhina wanted heroin, to get high on before overdosing with a cocktail of other pain-relieving drugs. Yao wanted a gun, and to go last, so he could “help” the others before himself. Later, while Grace is in his makeshift office, an explosion rattles the base, and they realize that the research institute exploded, killing all the workers inside, including DuBois and his backup Shapiro, meaning now the mission does not have a science specialist.
Everything on the ship is going well until the lights and all of Grace’s electrical systems turn off. He and Rocky realize that somehow the Taumoeba had escaped the breeding tanks and gotten into nearly every place in the ship where Astrophage were, including the fuel. Nearly all of Grace’s fuel was gone. He and Rocky realized from their small experiments that the Taumoeba seem to thrive in environments without any nitrogen, but will die with any more than trace nitrogen amounts. They use some nitrogen to clean out the fuel tanks, hoping to kill the Taumoeba.
Grace, in the past, enters a meeting with Stratt and the other leaders of the project. They tell him that they have selected the science specialist for the mission—him. He has the coma resistance gene markers, and he has been basically trained on everything necessary for the mission. Grace says he needs to think about it, and Stratt gives him until 5pm that evening. When he meets with her again, he says he’s decided not to go, because he has to stay for the kids; Stratt becomes aggressive, and tells him that they’re going to force him to go anyway. He will be sedated, and she will tell the others on board that he was nervous about the launch because he had not trained to be an astronaut, just to do the science onboard. When he woke up, they might be angry at Stratt, but they would already be on the mission. Grace tries to run away, but he is stopped and sedated.
On the ship, Grace and Rocky are able to connect their ships back together. Grace finds some Taumoeba that have survived in minimal nitrogen environments, so he breeds them together, working on increasing their nitrogen tolerance. Venus has a nitrogen concentration of about 3.5%, and Threeworld (the planet with Astrophage breeding in Rocky’s system) has a concentration of about 8%. Over time, the Taumoeba become more and more nitrogen resistant, and they eventually reach a strain that is resistant at about 8.5% nitrogen, meaning they’ve found the solution.
The two of them work to refuel Grace’s ship, since Rocky had plenty of fuel left over. They modify the beetles, the probes to send to Earth, so that they hold Taumoeba breeding containers and can be sent back to Earth just in case the Hail Mary doesn’t have enough fuel or runs into another problem. Then they say goodbye to one another and head off in opposite directions. Grace checks the Petrova wavelength consistently, watching Rocky’s ship get further and further away based on the thrust from the Astrophage fuel.
Months into his return journey, Grace checks some of his Astrophage and realizes that they’ve been killed by Taumoeba, but the Taumoeba were not supposed to be there. He notices that the Taumoeba have evolved both to be resistant to nitrogen and to find ways to get through xenonite; the tanks made from xenonite all have dead Astrophage, but the tanks made of metal alloys and plastic do not. He is able to make secondary containers to stop the spread of Taumoeba, but he also realizes that Rocky’s ship is made of primarily xenonite, including his fuel tanks. Grace can either continue to Earth, hoping to make it back alive, or he can try to find Rocky’s ship, floating dead in space, and rescue him.
Grace decides to send the beetles back to Earth and find Rocky. He is able to locate the ship and Rocky is thrilled to see him. Grace brings Rocky on board the Hail Mary, and they plot a course to Erid. Grace tells Rocky that he’s most likely going to die, either before they get there or soon after, since he will run out of food. Eridian food all has heavy metals in it that are extremely toxic to humans. Rocky asks if Grace could eat Taumoeba, and he considers this, thinking that it could actually work.
In the last chapter, Grace wakes up on Erid, sixteen years after they had arrived back. His body is much older now, especially with the increased gravity on Erid. They built him a dome in which he can breathe Earth-like atmosphere. They also figured out how to culture some of his cells, so they have made him lab-grown meat to eat along with the Taumoeba. Rocky tells Grace that the scientific council has been tracking Sol, and notes that it has returned to full luminance—that means that the beetles got back to Earth, and they were able to reverse the damage done by Astrophage. Grace says he has a meeting to go to, and he heads to a classroom where Eridian children are excited to learn from him again.
Amaze
I finished reading this last night, and I don’t know if I’ve ever sobbed that hard after the final sentence of of a book. Andy Weir definitely knows what he’s doing. Sometimes, I really do enjoy a book with an ambiguous ending, or one where the threads do not tie up nicely.
But this book, with what I believe is a perfect finale, is always welcome. I love that Grace and Rocky are together. I love that they still recognize that he does not have much time remaining, but the Eridians build him a home and keep him comfortable anyway. I love that they mention that Sol has returned to its original state. I love that Grace gets to teach a new set of children.
The way that this book is written makes it an exciting one from the very beginning. It’s an interesting mechanic that I think could be abused, but Weir perfectly navigates the provision of information to both us and Ryland Grace. We get to learn who he is and about his life as he learns it too, and it is incredibly effective. It makes the revelations of him being forced onto the mission even more impactful and devastating.
He also has a fun way of writing characters. I’ve heard plenty of praise for The Martian being accessible, comedic, and conversational, and this is no different, but I feel like it’s more refined in Project Hail Mary. His characterization shines through in how Grace thinks and speaks. He rarely, if ever, curses, and we learn that he is a teacher; I love how consistent and ingrained that is to his character.
Rocky, too, is phenomenally characterized. I think it could be so easy to have both of them be extremely similar, especially because we are reading from Grace’s perspective and he is translating into English, rather than us reading directly what Rocky says. But they are unique characters, with unique motivations and reactions. I love seeing how excited Rocky is. I love that the alien race is so different to humanity.
Rocky might be one of my favorite characters ever written. I am increasingly nervous and buzzing with excitement to see him on the big screen. From what little we’ve gotten in the movie trailers, I have a lot of hope that they’re going to do him a great deal of justice.
I cannot wait to see what they do with this story. I cannot wait to reread this book again, maybe after another five years passes. I cannot wait to read what else Andy Weir cooks up, if he continues to write. Until then, I’ll be singing the praises of Project Hail Mary for a long, long time.
Total pages read so far, 2026: 2,457
Total books read so far, 2026: 6
Next book: Five Little Pigs by Agatha Christie
Good one to read on my upcoming long flight?