Isaac Asimov & Janet Asimov 
Norby the Mixed-Up Robot [EPUB ebook] 

A Space Academy student and his time-travelling robot stop an evil villain from taking over the Solar System in this children’s sci-fi classic. Fourteen-year-old Jeff Wells, a cadet at the Space Academy on Mars, is in danger of being kicked out unless he can improve his grades. With a little help from the academy’s commandant, Jeff finds a robot named Norby to help him study. But Norby’s no ordinary robot. He has the only mini-anti-gravity device in existence. Norby’s special abilities suddenly come in handy when a villain named Ing targets Jeff’s older brother in his quest to conquer the Solar System. When Ing takes over Manhattan Island, renaming it “the Kingdom of Ing, ” Norby and Jeff put studying aside to teach Ing a lesson!