This book has an engaging plot that kept me hooked. It was fun watching the main character solve problems. It's always great to see some sci-fi that takes astronautics and space seriously rather than hand-waving it away with artificial gravity and FTL. Even if it is curiously done: there are no checklists in the spaceship, no packet of information on the crew in case of amnesia despite otherwise meticulous preparation.

It's a pity the author didn't put anywhere as much effort in the biology in the book as he did into the astronomy and physics. Rocky was fun but the astrobiology was kind of paper-thin. The panspermia implied doesn't line up with what we know about the development of life on Earth. Also: (view spoiler)

Also frustrating were the reactionary gender politics. Stratt, the leader of the project, will only accept heterosexual men as astronauts on the basis of reactionist drivel that is not really challenged (e.g. plenty of evidence that gender-balanced teams are more effective) and then the narrative validates Stratt by (view spoiler)

The main character, Ryland Grace, meets an alien, and decides to use he/him pronouns: "I'm going to go with ‘he’ for now, because it just seems rude to call a thinking being ‘it.’ ”"

Seriously dude? The only pronouns you can think of are he/him and it/its? She/her is beyond your comprehension, let alone the obvious they/them pronouns? You expect me to believe that the main character is a schoolteacher in the 2020s and has never learnt any other pronouns? What rock is Grace living under?

The alien, Rocky, is described as biologically hermaphroditic. Yet Grace doesn't reconsider pronouns when he finds this out.

I'm also not convinced that Rocky is actually hermaphroditic. Rocky's species is described vaguely as mating by having each would-be partner lay an egg, and the eggs fuse to produce one offspring. That sounds a lot more like isogamy to me than cosexuality. (If each parent laid and egg and fertilized the other's egg that would be cosexuality, a type of hermaphroditism. Isogamy is when there is no difference between egg and sperm; each parent provides an identically sized gamete which together become the child.)

The acknowledgements at the end of the book make clear the author talked to physics and astronomy people to inform the book. But not a single biologist nor science teacher are listed and it shows. Fun read but the more I stop and think about it the more holes occur to me. Hopefully they'll at least fix the pronoun problem in the movie