A traditional compass will not work on Mars because the planet lacks a global magnetic field.

Earth’s magnetic field is generated by the geodynamo, a process where the rotating, convecting, and electrically conducting liquid iron in the outer core creates a global magnetic envelope. Mars once had a similar dynamo, but it ceased approximately 4.2 billion years ago. Scientists believe the smaller size of Mars caused its core to cool more rapidly than Earth's, effectively 'freezing' the convection necessary to maintain a magnetic field.Data from NASA’s Mars Global Surveyor, which arrived at the Red Planet in 1997, confirmed that Mars lacks a global dipole field. Instead, the spacecraft detected 'crustal remnants' or localized magnetic umbrellas. These are patches of the Martian surface, particularly in the southern hemisphere, that contain magnetized minerals like magnetite and pyrrhotite. These minerals were locked in place while the global field still existed.Because these magnetic patches are scattered and vary in strength, they do not provide a unified 'North' for navigation. A traditional magnetic compass would be influenced by the nearest magnetized rock rather than the planet's poles. For future exploration, NASA and other agencies must rely on celestial navigation, gyroscopes, or high-precision GPS-like satellite arrays to determine direction on the Martian surface.