There is a large part of this book that makes it unique in a sorta twisted way that could of been avoided. In the beginning of the book the story starts on earth with Fords house about to be destroyed, which it ends up getting, but for a whole other reason. Before you know it there are aliens come and blow up earth and with just enough time for Ford and Arthur to escape. The main problem I have with this is that there is many other ways they could have been forced off earth. Such as they go to prison and need to escape which could be a whole book in itself. They could have also been forced off because of disease spreading, or nukes. Those two would at lease leave a couple hundred survivors that they have to save as well.