Definite 5 stars. Really enjoyed this scifi caper - imminent destruction of life on earth, alien buddy capers, lots of science mixed in with the fiction. And I liked the dual timeline story, how you found out more of the back story as the “current” storyline advanced. The only criticism I had, which is minor, is that it felt very much like the same character as in The Martian - like either a sequel, or maybe the same character in an alternate universe. But either way, greatly enjoyed and will probably start working my way through Andy Weirs back catalogue now.