That was a trip. I spent the last 150 pages with my head in my hands, elbows propping open the pages. I developed a tension neck-ache from the stress of hunching over to read it. And all I can say is that it was totally worth it. Gretchen fun fact time: I wanted to be an astronaut more than anything else as a kid. I had a NASA jumpsuit that I'd wear to career days. That gradually transferred to wanting to be an aerospace engineer so I could work for NASA and, I don't know, sometimes I still wonder what would have happened if I'd taken that path. (Answer: I didn't care for engineering. Librarianship is a much, much better path for me to be on.) But I visited NASA in Houston a couple of years ago and I felt those same pangs for a dream deferred. There's a Sally Ride quote I really like: "I've discovered that half the people would love to go into space and there's no need to explain it to them. The other half can't understand and I couldn't explain it to them. If someone doesn't know why, I can't explain it." I get that desire. I really do. 
 So, I mean, of course I was going to love this book. The same things that make Mark Watney an ideal candidate for space travel--his need to diffuse a stressful situation with humor, his optimism, and his problem-solving skills--are the same things that make him such an engaging protagonist. I felt better about the science-y bits once I realized that it was perfectly okay that I didn't understand most of them. I won't say much more about what happens, other than to implore you to read it for yourself, especially if you're among the 50% who would give anything to see the world from a spaceship.