C.S. Lewis used the name Malacandra for Mars in Out of the Silent Planet, the first novel of his Space Trilogy. The book was published in 1938 and follows the philologist Elwin Ransom after he is taken from Earth.
In Lewis’s fictional cosmology, the inhabitants of Mars call their planet Malacandra. Earth is called Thulcandra, meaning the silent planet, because it has become spiritually isolated from the other worlds. The novel’s invented terminology draws on Lewis’s interest in language, mythology, and medieval cosmology.
Perelandra is not another name for Mars. It is the Venus-like world visited in the trilogy’s second novel, Perelandra. This distinction is a frequent source of confusion because both names belong to the same fictional universe.
The trilogy continues with Perelandra and That Hideous Strength. Although the books contain space travel and speculative technology, Lewis’s main concerns include morality, free will, corruption, and humanity’s relationship with the cosmos.