The purpose of this book is to share collective experience on human spaceflight operations. For the many authors, this is nothing less than a work of passion. They are sharing their life's work with the goal of passing on their experience to the next generation of space engineers, designers, operators, and crew.

The time of Carnival represents a "wild" time at the end of winter and pointing to the beginning of a new season. It is characterized by the irruption of border figures, animal masks, characters which recall the world of the dead and which bring within themselves the germ of a vital force, of the energy that produces the reawakening of nature and announces the growth and fertility of the new crops. This wild domain shows itself under the shapes of a contiguity between human and animal: the costumes, the masks, refer to a world in which the characteristics of the human and those of the animal are fused and intertwined. Among these figures, in particular, emerge those of the Wild Man, the human being who takes on animal-like attributes and aspects, and of the Bear, the animal that, more than all the others, gets as close as possible to the human and seems to reflect a deformed image of it. Such symbolic images come from far off times and places to tell a story that belongs to our common origins. The bear assumes attributes and functions alike in very different cultural contexts, such as the Sámi of Finland or North-American hunter-gatherers, and represents a boundary between the world of nature and the human world, between the domain of animals and the difficult construction of humanity: a process continued for centuries, perhaps millennia, and which cannot still be said complete.