This is the last of Ali Hazelwood's STEM novellas, and I honestly think this was the best one. It's short, but I felt like it really told the story, even with a smaller window to do so. Hannah and Ian had some great chemistry and I loved their backstory. The author really is amazing with her details too! You can tell she researched NASA and everything related to it, and it shows. I sort of didn't like how Hannah rejected Ian in the beginning, in the past flashbacks; her reasoning just wasn't solid. Then, she was mad at Ian for rejecting her proposal but didn't even really give him the chance to explain and just went ahead and did it anyways, despite the danger (and he had to come rescue her because if her stupidity). Also, it was kind of weird to compare her body to Mars? Like, what was that? I do like that Ali makes the sex scenes so real. It's got real life elements to it, like the talking and the fumbling around and the vulnerability and the not so perfect first time. But overall, I do think it was good and I love Ali's writing. I was happy to see each of our three girls together with their respective boyfriends and to know they got their happy endings. Great end to a short but sweet little series!