Project Hail Mary Plot Review with Spoilers

Dr. Ryland Grace wakes up in space. He works through the waking-up process and the ship computer is smart enough to not let him have access to more of the ship than he deserves. As Grace remembers who he is and what he's doing, he also remembers who he was on earth. He was a high school physics teacher with a past as an inflammatory scientist. He remembers that the earth is in danger because of a new life form called Astrophage (star eater) which has found our Sun and is slowly stealing the energy from it that earth needs for stability and survival. Grace remembers that he is on a suicide mission to the nearest star (Tau Ceti) that has not been diminished by Astrophage. His mission is to learn how to save the Sun before humans go extinct. Astrophage also provided the keys to execute Project Hail Mary-mass to energy conversion along with massive energy storage. The spaceship is fueled by, powered by, and propelled by Astrophage. Grace had been in a medically induced coma for over 4 years while the Hail Mary traveled to the Tau Ceti star system he needs to investigate. Grace wakes up to find his two crewmates dead, so he is all alone until an alien spaceship (Blip-A) appears on his scopes. Grace meets Rocky, an alien who is also on a mission to save his world from Astrophage. Grace, the scientist, and Rocky, the engineer, work together to solve the Astrophage problem. Rocky is a 5 armed alien, used to an atmosphere 29 times the pressure of earth's atmosphere and made primarily of ammonia. Rocky works some engineering alien magic on the Hail Mary and moves in with Grace and they go hunting for an Astrophage predator. They find the predator, Toumoeba, which keeps the Astrophage population in check so it does not overwhelm Tau Ceti. Toumoebas eat Astrophage. Astrophage power both spaceships and protect Grace and Rocky from radiation. When the Hail Mary generators shut down, Grace finds Toumoeba in the generator system and fuel bays. Grace and Rocky do some desperate space operations to limp the Hail Mary back to the Blip-A, which has backup stores of Astrophage. During the trip, Grace and Rocky do some crazy genetic modifications to the Toumoeba to breed a strain that can survive in the atmospheres needed to save the Sun and Eridani (Rocky's sun). Rocky fixes up the Hail Mary and Blip-A, and Grace prepares Toumoeba farms for the trips back to each home planet. Early in the trip back to Earth, Grace learns that he has inadvertently engineered Toumoeba that can escape farms made with metal from Rocky's planet. Grace sends four probes to earth with data and steel Toumoeba farms back to earth, then turns around to save the Blip-A because Rocky doesn't know the Toumoeba can escape until it's too late. Grace saves Rocky and they return to save Eridani. Grace becomes a hero and lives in a dome on Rocky's planet.