Book notes: Project Hail Mary by Andy Weir

Project Hail Mary by Andy Weir book summary review and key ideas.

Get the audiobook on Audible 👇 (affiliate link)

Project Hail Mary by Andy Weir


A lone astronaut must save the earth from disaster in this incredible new science-based thriller from the number-one New York Times best-selling author of The Martian.

Ryland Grace is the sole survivor on a desperate, last-chance mission – and if he fails, humanity and the Earth itself will perish.

Except that right now, he doesn’t know that. He can’t even remember his own name, let alone the nature of his assignment or how to complete it.

All he knows is that he’s been asleep for a very, very long time. And he’s just been awakened to find himself millions of miles from home, with nothing but two corpses for company.

His crewmates dead, his memories fuzzily returning, he realizes that an impossible task now confronts him. Alone on this tiny ship that’s been cobbled together by every government and space agency on the planet and hurled into the depths of space, it’s up to him to conquer an extinction-level threat to our species.

And thanks to an unexpected ally, he just might have a chance.

Part scientific mystery, part dazzling interstellar journey, Project Hail Mary is a tale of discovery, speculation, and survival to rival The Martian – while taking us to places it never dreamed of going.” -Audible

~If you enjoy my summary, please consider buying me a coffee via my Ko-Fi link (click the button below) or support this blog in one of several ways! 📖 🎓

I appreciate every donation as it goes directly to the maintenance costs of my blog and creation of new content. 😊

Buy Me a Coffee at

Opening thoughts:

I saw that a friend of mine recommended this book on social media and it sounded like a really good book. It also had really good reviews, but I’m not really sure what to expect. Sometimes that’s the best way to go into a book.

Key notes:

Chapter 1 

  • He woke up in a hospital bed with tubes coming out of him and a computer asking him questions. But he could barely move his body and wasn’t sure what was going on
  • He doesn’t remember who he is or his name, but had a flashback of his life in San Francisco
    • He found two other people in the room but they have long been deceased. He suspects he’s been in a coma for a while
  • He’s able to move and walk around now and figures out that he is a scientist when he enters the lab in the next room
  • He realizes that something is off about gravity. After doing calculations, he realizes that gravity has increased and therefore he’s not on earth

Chapter 2

  • He had another flashback memory of talking with a close friend of his about how the sun was slowly dying and it seemed like energy was being siphoned off to another place
  • He remembered that NASA seemed to have come across alien life on their way to Venus
    • He also remembered that he was a schoolteacher, single, but he liked kids 

Chapter 3

  • He was able to study the little black dots and came to the conclusion that it is a living organism that absorbs the sun stores it and uses it for propulsion
    • He called it Astrophage
  • He did some calculations and realized that he is in another solar system

Chapter 4

  • He told his students that the Astrophage would devastate their world, which motivated him to get back into the lab and continue his research
  • He realizes he’s on a suicide mission to send his findings back to Earth as there’s not enough fuel to get him back home

Chapter 5

  • He was flown by fighter jets across the world to a Chinese aircraft carrier to explain his findings to the gathering of specialists assigned to Project Hail Mary
  • Stratt explained to him that their plan was to figure out how to mass-produce Astrophage and then use it as fuel for their interstellar ship to fly to the star that strangely isn’t infected by Astrophage 12 light-years away
    • He would be living on that carrier full time for the time being

Chapter 6 

  • When he gets to the star, he comes across an alien ship powered by astrophage as well

Chapter 7

  • He received the hot cylinder object from the alien and started to run tests

Chapter 8

  • The alien metal cylinder had a miniature model of their solar system
    • He made his own and sent it back to them

Chapter 9

  • He had a flashback of seeing the spin drive for the first time and how it operated using the Astrophage
  • The aliens made a tunnel that attached to both ships and allowed for a vacuum airlock between them

Chapter 10

  • After some communication, he finds out that the 5 legged spider alien breathes ammonium and has 29 times the atmospheric pressure he does
  • He communicated with Rocky (the alien) and they exchanged clocks so that they can figure out how they do time

Chapter 11

Chapter 12

  • He started to record Rocky’s sounds into a database so he can translate his language in real-time
  • They did more language translations and measurement translations
    • He also found out that Rocky had a crew of 23 and now it’s just him alone

Chapter 13

  • They started the production of Astrophage on a mass scale

Chapter 14

  • One of the leading climatologists said at their current rate, half of the human population will die in 19 years
    • The idea was they were going to try to increase global warming to buy them more time, at least 27 years
  • The plan was to blow up chunks of Antarctica in order to release methane into the air and increase global warming
    • This would give them more time for Project Hail Mary
  • Rocky created a protective shell that would allow him to explore his ship

Chapter 15

  • Rocky wanted to bring his tools into Ryland’s lab because the technology is better, allowing them to figure out Astrophage problem together
  • Rocky has been there for 46 years, and his species typically lives hundreds of years

Chapter 16

  • He told Rocky that this was a one-way trip for him and that humans didn’t have a lot of time
    • Rocky mentioned he has a lot of extra fuel that he could use and give it to Ryland
  • He was able to witness how Eridians eat before they sleep, which was pretty gross

Chapter 17

  • After sampling from the plants at Adrianne, they came to the conclusion that it was the Astrophage homeworld
    • It had a lot of life that includes organisms or predators that eat Astrophage which keeps the system the ecosystem in balance
  • Their solution was to bring the predator organism back to their solar systems in order to correct the imbalance of the Astrophage and save their stars

Chapter 18

  • The scientist explained how the beetle machines were designed to return to earth as quickly as possible by themselves

Chapter 19

  • Rocky saved Ryland but sacrificed himself

Chapter 20

  • He tried his best to help Rocky’s injuries

Chapter 21

  • He remembers asking the crew how they want to die and making the preparations for them
  • Ryland has a theory of why his and Rocky species have similar intelligence: intelligence develops proportionally to the amount of gravity
  • He and Rocky agreed that they are good people from their respective species because they were willing to die for them
  • They discovered the predator of Astrophage and called it Taumoeba
  • They run experiments to see if the predator can survive the conditions of Venus and three world

Chapter 22

  • The predator organism got loose and ate all of the Astrophage fuel on the ship
    • Their plan was for Rocky to clean out the generator and use their remaining fuel to get back to his ship
  • They were able to use the Beatles to stop the ship’s rotation and now they’ll figure out how to fly back to Rocky’s ship

Chapter 23

  • After the primary and secondary science specialists died in an Astrophage accident, Ryland became the best next best replacement
    • He had four hours to decide if he wants to go
  • Ryland didn’t want to go, but Stratt ended up forcing him to go and told him she would give him a drug that would induce amnesia for a short period of time

Chapter 24

  • They discovered that the Taumoeba were susceptible to nitrogen
    • The plan was to breed nitrogen-resistant versions so that they could survive Venus and Three-World
  • They managed to find Rocky’s ship and fly towards it

Chapter 25

  • They successfully bred Taumoeba which can survive Three-World nitrogen levels and Venus nitrogen levels
    • Rocky also built replacement fuel storage bays for Dr. Grace’s ship
  • They give each other a bittersweet goodbye once they were all set for the trip home

Chapter 26

Chapter 27

  • The Taumoeba got loose again but it seemed contained for the moment

Chapter 28

  • He realized that the 8.2 TM could go through Xenonite

Chapter 29

  • He decided to send the Beatles to earth and use his last remaining resources to save Rocky
  • He managed to find Rocky’s ship but he had to figure out how to contact him inside
  • He finds Rocky but tells him that he doesn’t have enough food to go home
    • Rocky suggests eating the TM which might work

Chapter 30

  • He spent a few years on Erid
  • The Eridian people were great hosts and committed to doing everything they could to keep him alive
  • All of the scientists on the planet came together to solve his nutrition problem and help create vitamins and eventually proteins, a.k.a. human meat made from cloning him
  • Rocky gave him the news that Sol returned to prior luminosity, which means that the humans were able to solve the Astrophage problem
  • He thought that he might return to earth one day even though so much time has passed
    • But for now, he’s happy with his job on this planet, which is being a teacher to Eridian students

Closing thoughts:

I really enjoyed this book! As far as Sci-Fi books go, this is definitely a solid choice for anyone who loves this genre.

I found myself on the edge of my seat and wanting to continue listening even when I finished my commute. The storytelling was well-done, and the pacing was great. I loved how the mystery of how he got there unfolded in just the right way and right time.

This is one of those books that would be awesome if it turned into a movie, but also these sorts of books-to-movie jumps can be hit or miss. Either way, I’d definitely watch it.

Overall, if you like the science fiction genre, I’d highly recommend checking this out.


Dr. Ryland Grace is sent 12 lightyears away to another solar system to solve the problem of Earth’s dying sun. Along the way, he meets an alien in the same predicament as him.

Similar books:


Rating: 4 out of 5.


Subscribe for More Summaries👇

Success! You're on the list.

Try Audible for audiobooks 📚🎧

Personal recommendation: For the last 6 years, I’ve used Audible to listen to all of my favorite books. It’s easy to use, cost-effective, and they have the best library of audiobooks.

If you use my affiliate links below, not only will you get a special offer, but it’ll help support the costs to maintain this blog! 😊👇

Try Audible and Get Two Free Audiobooks

Audible Gift Memberships 

Please donate! 🙂

Please consider a small donation to help support my blog ^_^ I love providing free book notes and other content. Any donations help me maintain my website and create content consistently. Thanks everyone for the continued support!


5 thoughts on “Book notes: Project Hail Mary by Andy Weir”

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: