I started reading this book off my Kindle for iPhone -- had bought it some time before -- as relaxing lunchtime reading at the Bear Tooth (Anchorage) the day before Thanksgiving. Really, I chose it because I was in the midst of NaNoWriMo, working on a story called "Cycler" & thinking about what my character Esti Gusev, born & bred on Mars, will experience when she takes a mag launcher into space for her trip to Earth. "Martian" is synonymous with "has lived her whole life at 1/3 of Earth's gravity" -- she's had to work her hiney off to get strong enough to withstand Earth gravity, much more so to take a launcher into space instead of riding the space elevator. So, what will it be for her to be pressed back into her seat at 2 or 3 times Earth g as she rises to orbit?
Much to my surprise, as I read the chapter in this book about gravity, I discovered that I'd had Esti work so hard that she was well-equipped to deal with the high g-force for that brief duration -- what really messes her up: microgravity. From low Mars orbit to rendezvous with the cycler in which she'll travel to Earth, she gets sick as a... well, not as a dog, but rather as sick as over one-half of all astronauts & cosmonauts who've ever been to space. What sickens them is a condition called Space Adaptation Syndrome, which is caused by physiological changes due to the lack of the force of gravity that the species of Earth evolved under.
This discovery added whole new dimensions to Esti's experience in space, & her first days on the cycler. As if to underscore it, my digestive system on the day after Thanksgiving (but not because of Thanksgiving dinner: nobody else got sick -- had to be something else I ate) decided to channel Esti's digestive system. I.e., I felt pretty damn bad all that day, though fortunately I was not wearing a spacesuit helmet -- vomiting inside one, as Neil Comins points out, can be quite dangerous to one's health.
I got better, Esti got better, & the book has already proven invaluable as a research tool for my ongoing writing in my Cold/Long Dark story universe. I'm reading it all out of order, though. Right now I'm reading the stuff about radiation hazards in space. The radiation dangers are so extreme for long-term travel in space, that if I were to retain complete fidelity to science, I'd have to give up this story universe altogether. Therefore I will follow that tried & true method of all science fiction writers: I'll fudge a bit.
I've dinged off one star because some of the "Mack's Log" stories used to illustrate the science verge on the cheesy -- Neil Comins is, after all, an astronomer & science writer, not a storyteller. ;) But all else is good. This book is immensely readable, interestingly written, & is comprehensible to the intelligent non-scientist reader. I particularly recommend it to writers like me who might want to know a few things before they have their astronauts do something really stupid.
This is my review from partway through the book -- perhaps I'll write more later, after I've finished it. (I can't tell you how many pages I've read so far because I'm reading it out of order and in the Kindle for iPhone app, where there are no page numbers, must locations.)