Best for readers who enjoy contemplative space adventure with a technical spine, especially those curious about choice, determinism, and the many-worlds mood. Teens with a solid science vocabulary can handle it, but it sings most for adult book clubs that like to argue kindly about ethics.
Content notes: sustained tension, brief mentions of past loss, scenes of physical peril in vacuum and on ice, no graphic violence or sexual content. Science is explained in-voice rather than with appendices, so hand it to readers who enjoy learning as they go.