The characters' voices started to sound alike and were not distinct, although Annie, who works for NASA, swears like a pirate or a parrot. Speaking of swearing Mark Whatley reacts to most mishaps with "I'm fucked." Not exactly beautiful writing and even that got boring. The flashback and letter transitions were not smooth at times. Most chapters with Whatley made me feel like I was reading a technical manual dense in its math and chemistry. For instance, "The regulator [atmospheric regulator] uses freeze-separation to sort out the gasses. When it decides there's too much oxygen, it starts collecting air in a tank and cooling it to 90 kelvin. That makes the oxygen turn to liquid, but leaves the nitrogen (condensation point: 77K0 still gaseous. Then it stores the O2." Once in awhile would have been fine but this is basically a book that's main character is the science itself. No thanks. This book has really high ratings in Goodreads and was recommended by someone that normally likes the same books as me, but I was just trying to survive reading it to the end.