That’s CS Lewis and Arthur C Clarke, rather than the American explorers. The two of them corresponded and met once. Clarke wrote:

“Less sympathetic to our aims was Dr. C. S. Lewis, author of two of the very few works of space fiction that can be classed as literature -– ‘Out of the Silent Planet’ and ‘Perelandra’. Both of these fine books contained attacks on scientists in general, and astronauts in particular, which aroused my ire. I was especially incensed by a passage in ‘Perelandra’ referring to ‘little Interplanetary Societies and Rocketry Clubs’…

An extensive correspondence with Dr. Lewis led to a meeting in a famous Oxford pub, the Eastgate… Needless to say, neither side converted the other. But a fine time was had by all, and when, some hours later, we emerged a little unsteadily from the Eastgate, Dr. Lewis’ parting words were, ‘I’m sure you’re very wicked people – but how dull it would be if everyone was good’. ”

H/T: The Inklings blog.