All Elizabeth Morley's books finish with a short postscript explaining the real-life facts behind the story; for, while her purpose is first and foremost to entertain, much of her inspiration comes from the fascinating world - and universe - around us. The hedgehogs are very much like us (with a few added extras - notably the ability to hibernate). The locations are inspired by real places, most of which the author has visited (such as France, Germany and Iceland) but a few of which she has not (a video tour by astronaut Suni Williams was sadly the closest she got to the International Space Station). The plots also take in real events (such as the planning for Operation Sea Lion in World War II) and real science and technology (from thermite's ability to burn under water to NASA's robot-cum-astronaut, Robonaut). For her third book, there is also an explanation of the scientific theories behind the science fiction, European involvement in space exploration and even how to become an astronaut.