Project Hail Mary by Andy Weir

Project Hail Mary by Andy Weir follows Ryland Grace, an amnesiac scientist who wakes up alone on a spaceship, discovering he is on a desperate, one-way mission to save Earth from an alien microorganism, "Astrophage," that is dimming the sun. He teams up with an alien named Rocky to find a solution, blending hard science, suspense, and unexpected friendship.