Martian calendar

A martian calendar is simply a system of timekeeping for Mars, perhaps the simplest of which is the sol-tracking done with the Viking landers on Arean soil.

Before the Purge, the Arean calendar is used to track time on Mars, though many other calendars were proposed. It is a perpetual calendar whose implementation is largely independent of Earth, making it attractive for the initial colonists. Since the Battle of Sol, the calendar is still used by ex-Martians who don't care for the Helios calendar.