Named after Francios-Marie Arouet Voltaire - French writer (1694-1778).
Voltaire is an impact crater on Mars's moon Deimos and is approximately 3 km across. Voltaire crater is one of two named features on Deimos, the other being Swift crater. On 10 July 2006, Mars Global Surveyor took an image of Deimos from 22,985 km away showing Voltaire crater and Swift crater. (wikipedia entry)
A crater is a circular depression likely created by an impact event. On Deimos they are named after deceased authors who wrote about martian satellites.
Sorry, there hasn't been a good map made for this world yet :(