Abstract: We present analog clocks fitted to the Mars solar day. These clocks use the standard Earth-based second of the International System of Units (SI) as their operational unit of time, unlike current practice for Mars timekeeping. We discuss the importance of preserving the SI second. On this basis, we identify the two analog clocks most suitable for public use by a future Mars population. These are a 20-hour clock with a hand motion similar to that of the standard Earth clock, and a 24-hour clock with a novel “Martian” hand motion which strikes the hour when all 3 hands converge onto that hour mark on the dial. Both clocks have Earth-day equivalents to assist learning. We also present a 24-hour “SpaceClock”, similar to the Martian clock but with no favored reference plane, hence equally readable from any viewing orientation.