Space travel, or space flight (less often, starfaring or star voyaging) is a classic science-fiction theme that has captivated the public and is almost archetypal for science fiction. Space travel, interplanetary or interstellar, is usually performed in space ships, and spacecraft propulsion in various works ranges from the scientifically plausible to the totally fictitious.
While some writers focus on realistic, scientific, and educational aspects of space travel, other writers see this concept as a metaphor for freedom, including "free[ing] mankind from the prison of the solar system". Though the science-fiction rocket has been described as a 20th-century icon, according to The Encyclopedia of Science Fiction "The means by which space flight has been achieved in sf – its many and various spaceships – have always been of secondary importance to the mythical impact of the theme". Works related to space travel have popularized such concepts as time dilation, space stations, and space colonization.
While generally associated with science fiction, space travel has also occasionally featured in fantasy, sometimes involving magic or supernatural entities such as angels.
History
A classic, defining trope of the science-fiction genre is that the action takes place in space, either aboard a spaceship or on another planet. Early works of science fiction, termed "proto SF" – such as novels by 17th-century writers Francis Godwin and Cyrano de Bergerac, and by astronomer Johannes Kepler – include "lunar romances", much of whose action takes place on the Moon. Science-fiction critic George Slusser also pointed to Christopher Marlowe's Doctor Faustus (1604) – in which the main character is able to see the entire Earth from high above – and noted the connections of space travel to earlier dreams of flight and air travel, as far back as the writings of Plato and Socrates. In such a grand view, space travel, and inventions such as various forms of "star drive", can be seen as metaphors for freedom, including "free[ing] mankind from the prison of the solar system".
In the following centuries, while science fiction addressed many aspects of futuristic science as well as space travel, space travel proved the more influential with the genre's writers and readers, evoking their sense of wonder. Most works were mainly intended to amuse readers, but a small number, often by authors with a scholarly background, sought to educate readers about related aspects of science, including astronomy; this was the motive of the influential American editor Hugo Gernsback, who dubbed it "sugar-coated science" and "scientifiction". Science-fiction magazines, including Gernsback's Science Wonder Stories, alongside works of pure fiction, discussed the feasibility of space travel; many science-fiction writers also published nonfiction works on space travel, such as Willy Ley's articles and David Lasser's book, The Conquest of Space (1931).
From the late 19th and early 20th centuries on, there was a visible distinction between the more "realistic", scientific fiction (which would later evolve into hard sf)), whose authors, often scientists like Konstantin Tsiolkovsky and Max Valier, focused on the more plausible concept of interplanetary travel (to the Moon or Mars); and the more grandiose, less realistic stories of "escape from Earth into a Universe filled with worlds", which gave rise to the genre of space opera, pioneered by E. E. Smith and popularized by the television series Star Trek, which debuted in 1966. This trend continues to the present, with some works focusing on "the myth of space flight", and others on "realistic examination of space flight"; the difference can be described as that between the authors' concern with the "imaginative horizons rather than hardware".