A Good Story Is Hard to Find recently did some episodes on C. S. Lewis's Space Trilogy (also called the Cosmic Trilogy):
Good Story 202: Out of the Silent Planet
Good Story 204: Perelandra
Good Story 206: That Hideous Strength
This made me want to re-read the whole trilogy, so they will be the next fortnightly books. each of the three is radically different.
Out of the Silent Planet was published in 1938; it is heavily influenced by Olaf Stapledon (e.g., Last and First Men) and H. G. Wells (e.g., First Men in the Moon), and is perhaps the most successful example of science fiction written and published at the end of the pulp period before what usually gets called the Golden Age of Science Fiction.
Perelandra, published in 1943, is heavily influenced by Milton's Paradise Lost (Lewis had given his Ballard Matthews lectures, published as A Preface to Paradise Lost, in 1941); according to a later interview Lewis had with Kingsley Amis, it started (as many Lewis stories did) with a mental picture: floating islands. Lewis was also influenced in his writing by the structure of operas; as it happens, Donald Swann (of Flanders and Swann fame) made an opera of it in the 1960s, which was highly acclaimed at the time, but has tended not to be performed because of legal issues -- a pity because Swann himself thought it one of his best works, based on a work Lewis himself thought one of his best, in such a way that Lewis himself liked it. You can hear clips from a 2009 performance here.
That Hideous Strength: A Modern Fairy-Tale for Grown-Ups draws heavily on the stories of the Tower of Babel (the subject of the couplet that gives the book its title) and of King Arthur (the latter likely, as Tolkien thought, under the heavy influence of Charles Williams, and blends the science fiction of the first book with the operatic of the second. It is a near-future science fantasy, published in 1945 but set in a post-war England (usually thought to be about 1948). George Orwell wrote a review of it, and, while not liking the fantastic elements of the book at all, he nonetheless thought the social commentary aspect of it well done.
For the American market, Lewis made an abridged version of the long third book, which was published under the title, The Tortured Planet. I have it, so I will try to read it as well, and comment on some of the differences.