Warriors of the Sky: One Day, Earth Will Be Gone 3rd edition

Technology and pollution have caused a toxic cloud to sweep the Earth of life. Luckily, humans had warnings and have colonized the solar system. To stop a crisis of the sort from ever happening again, humans have decided to revert to the medieval ages, letting go of all machines. Elora was born in this world, raised in this world, her life is the sky. But when something horrible happens, her memory is gone. She learns to get by with the help of some friends--but then she and those close to her learn of a man who wishes to gain power by wielding guns and machinery. Elora, Eris, Alfie, Rolf, and Ceron must try and keep this from happening, in order to save the solar system from Earth's fate. But if Elora is forced to decide, what will she choose--friendship or memory?