The Viagens Interplanetarias series is a sequence of science fiction stories by L. Sprague de Camp, begun in the late 1940s and written under the influence of contemporary space opera and sword and planet stories, particularly Edgar Rice Burroughs's Martian novels. Set in the future in the 21st and 22nd centuries, the series is named for the quasi-public Terran agency portrayed as monopolizing interstellar travel, the Brazilian-dominated Viagens Interplanetarias ("Interplanetary Voyages" or "Interplanetary Tours" in Portuguese). It is also known as the Krishna series, as the majority of the stories belong to a sequence set on a fictional planet of that name. While de Camp started out as a science fiction writer and his early reputation was based on his short stories in the genre, the Viagens tales represent his only extended science fiction series.
The Viagens stories were written in two phases; the first, written between 1948 and 1953 and published between 1949 and 1958, was a burst of activity that produced the first four Krishna novels and most of the non-Krishna pieces, including all the short stories. The second, produced at a more deliberate pace from 1977–1992, comprised the remaining four Krishna novels and the two novels of the Kukulkan sequence. The early works established the setting of a cosmopolitan future interstellar civilization comprising both Terrans and a handful of other space-faring races who trade and squabble with each other while attempting to maintain a benign stewardship of the more primitive planetary societies with which they come into contact. The later works assumed but largely ignored this background, concentrating exclusively on the adventures of Terrans on the alien worlds of Krishna and Kukulkan.
The setting
The Viagens universe is not a picturesque backdrop for heroics, like those of de Camp's predecessors Edgar Rice Burroughs and E. E. "Doc" Smith, nor is it a carefully constructed and recounted future history like those of contemporaries Robert A. Heinlein, Isaac Asimov and Poul Anderson. Most of the stories take place in the 22nd century, after an initial period of exploration and diplomacy establishing the ground rules for interstellar commerce and contact, but before the higher civilization of the space-faring cultures has completely transformed those of the more primitive, planet-bound races. Given de Camp's view of even the most intelligent of beings as subject to the dictates of their instincts, emotions and self-interest, the Viagens universe represents a workable but decidedly imperfect future.
Just as de Camp attempted to do in the fantasy genre with his Pusadian stories for the Hyborian Age tales of Robert E. Howard, the Viagens tales represent both a tribute to contemporary space opera and sword and planet fiction and an attempt to "get them right", reconstructing the premises logically, without what he regarded as their technological, biological and anthropological absurdities. De Camp intended the stories as "pure entertainment in the form of light, humorous, swashbuckling, interplanetary adventure-romances - a sort of sophisticated Burroughs-type story, more carefully thought out than their prototypes." Thus he discarded such impossible but commonplace notions such as interfertility of human beings with humanoid alien races, civilizations possessing flying machines but no ground transport, bladed weapons and advanced gunnery coexisting in the same society, and faster than light travel.
De Camp did, however, underestimate the staggering impediments to even sub-light interstellar travel, assuming it would both be achieved quickly and soon develop into a relatively routine and comfortable system of commerce and travel linking nearby star-systems, much as sailing ships linked the early modern nations of Earth. He also assumed the parallel and convergent evolution of life on other worlds into types of higher multicellular lifeforms similar to those of Earth, and the ubiquity of intelligent life; thus his alien planets have both animal and plant life, with at least one species of animal life usually having achieved intelligence, and these alien intelligent species are in the main recognizably mammalian or reptilian.