I. Bulk properties: density = 3.96 gm/cm2 d; radius = 3389 km; moment of inertia = 0.36Ma2
II. Rotation and figure: period = 24h 37m; J2/q2 = 0.42 (close to Maclaurin spheroid (0.5), not despun)
III. Gravity field: good correlation of long wavelength equal potential surface with surface features, particularly with the Tharsis Uplift, which is associated with a large shield volcano.
IV. Composition and interior structure: mantle similar to primitive Earth mantle composed of the silicate pyrolite with enrichment in FeO (16% FeO compared to 8% in normal pyrolite). FeO enrichement makes surface appear reddish. On the whole, however, Mars contains less iron than Earth because of the absence of a dense iron oxide core. The central pressure of Mars is equivalent to the pressure at 1000 km in Earth; hence. little compressional effects are evident in its radial density structure. Radial structure models: (1) crust, FeO enriched mantle, molten Fe-FeS core at 2000 deg K isotherm; or (2) crust, FeO enriched mantle, solid Fe-Ni core.
V. Thermal structure and tectonics: 200 km thick lithosphere, volcanism in first 2-3 b.y. inferred from crater densities; thermal expansion by radioactive heating since formation leading to 10 km increase in radius and formation of canyons due to normal (tensional) faulting.
VI. Magnetic field: lacks an appreciable magnetic moment suggesting the lack of a convecting, electrically conducting core currently. However, recent Pathfinder orbiter observations find evidence for remanent magnetization in some regions of its crust, particularly over volcanic areas.
Click here to see results from Mars Pathfinder and here to see results from Mars Rover missions.