Another Heartland List book for middle grade readers, and I enjoyed it. Told from the POV of Res, a rover built to go to Mars, and Sophie, whose mom worked to build and code Res. Res has thoughts and feelings, despite being programmed as a robot. Beeps and boops. Sophie writes letters to Res, a cathartic way for her to handle her feelings and we get to watch her grow up through her letters. Book #79 in 2024