There is definitely a strong theme of overcoming prejudice that runs through Earth Star more so than its predecessor Earth Girl. At almost every turn Jarra was not just battling her own insecurities but was faced with a universe full of people that for the most part probably view her and those living on Earth as apes. 
 I have allergies so I must not be human 
 A ridiculous statement yes, but no more ridiculous than the reality of prejudice itself. When you really stop to think about the reasons behind the prejudices some people have, they all boil down to some such silly nonsense. And for the color of skin, twang to a voice and lack of immunities people are reviled. Treated as less even though they are in every other way just as human and deserving of respect as the next person. Again and again Jarra is the object of prejudice and it was an unfortunate thing to see but necessary to the plot. 
 I wanna push you around, I wanna push you down 
 Yes, I sang that in my head as I typed it. If you don't know the band Matchbox 20 then I can't help you. I was glad to see that Jarra and Fian had a much more developed relationship in this book. Of course they'd have to now that they've been through so much together and are actually a couple. Their playful banter and how Fian literally likes being pushed around by Jarra was cute. I don't know how other readers might take this but I adored their relationship. They are in that early phase of infatuation with each other and yet oddly enough they seem to know one another fairly well given the short amount of time that has actually passed. I found it refreshing to see how things between them have developed and I liked that Fian wasn't such a secondary character anymore. I have to say Earth Star also had a touch of nostalgia in it for me. It was great the way Earth's history, our not too far ago history infact, was woven into the story right along next to the fictional / futuristic history that the author created - all culminating in this fascinating far off future. The amazing things described made me wonder just how far off this future actually is. What with genetically created plants, recovered extinct animal species, medical regrowth tanks and teleporters. The wealth of nifty science fiction treats had me barely coming up for air between pages. Now mix in the sci-fi alien technology and it was a one sitting read. 
 Perception is 9 / 10ths of the law 
 Jarra has some really great things going for her as a character. She is curious and prone to getting into trouble, a victim of her own prejudices as well as those of others and hates talking about her feelings or anything even remotely emotional to a fault. She's also really smart in her field of historical study, and did I mention she brings a whole new meaning to the word stubborn? Fian claims he is stubborn, but he doesn't have anything on Jarra. hah! Anyways where am I going with this? So typically in young adult books you'll get introduced to that YA main character that is going to be the 'savior' or 'hero' in the book. Did that happen here? Of course it did - however the author did it right because she gives realistic and justifiable reasons for why Jarra is put into these situations. There are valid points to why Jarra is specifically chosen for these opportunities and why she more than anyone else is the best person for the job. Because of the way it was done and how the circumstances were always explained the reader was not constantly being asked to suspend their disbelief. That to me was what helped me enjoy Earth Star more than many other YA books and makes it well worth reading. 
 *note about the hardcover edition - the font is a bit small. Those who like bigger fonts might want to grab the e-copy instead.