I found this book completely by chance, and I don't regret taking it home with me in any way at all. Essentially, it's a story about a boy growing into a man who has spent his entire life outside of his ancestors' native planet, in Ganymede (the Solar System's biggest moon)and so sees "Earthers" as a completely different type of species.
I particularly enjoyed reading Part I of the story because it was written in an unbelievably accurate, convincing way; every little detail of how it felt like to live on that unforgiving Jupiter moon, where venturing outside of a man-made hut without protective gear would have your spine snapped and entrails estranged from your body by the bitter cold, was not forgotten. The reader receives a very vivid, panoramic impression of Ganymede, not only how the terrain on different regions of the moon varies, but also about how the physical forces interact on the moon, and detailed descriptions of the biological, chemical and physical applications mankind has introduced on the planet. The "science" in "science fiction" really has its meaning enforced in this book.
Part II is significantly less eventful than Part I, but still a very absorbing and masterfully written bundle of text. In part II, we see the teenager we met earlier as a fully grown man, dealing with the uncertainty and nostalgia of early manhood , and still trying to settle down the old ghosts of his childhood in the Settlement. In my opinion, the second part seemed to be a conclusion of the major themes in this novel, which were exclusively coming-of-age, change, death/destruction and the value of humanity. The very ending of it all was ambiguous, I think deliberately ambiguous, and I'm still unsure what to make of it. I suppose the author wished to demonstrate, in this way, the futility and uncertainty of every aspect of human understanding of the universe, which is an idea ubiquitously explored throughout the book.