Mars rover Resilience (“Res”) is being built and tested, primarily by NASA scientists Xander and Rania. Res’s understanding of the world is limited to the details in his coding and his observations of the humans around him. Although Rania (who speaks English and Arabic) resists anthropomorphizing the rover, Xander addresses Res as though Res is alive. Over time, Res begins to develop an understanding of human emotions—and even to feel them himself, though he knows this will not serve him well on Mars. When he arrives on the red planet, Res is accompanied by an excitable drone named Fly and, distantly, a satellite named Guardian. His mission is twofold: to locate a rover that went offline years ago and to search for evidence of long-ago life on Mars. Being an emotional rover, Res wants desperately to succeed and collect samples that will warrant his return to Earth. He is also willing to ignore orders from NASA to protect Fly when Fly is in danger, despite the risk to himself. Res’s stint on Mars is a long one; the passage of time is delineated in letters that Rania’s daughter, Sophie, writes to Res over the years. While Res’s eventual return to Earth and reunion with Rania and now-adult Sophie may be far-fetched considering NASA’s current limitations, it provides a nonetheless satisfying ending to a tender, gently humorous story with a great amount of heart.   (Ages 8-12)